AttributeList de-listifying:

[erichkeane]

Summary

Basically, "AttributeList" loses all list-like mechanisms, ParsedAttributes is switched to use a TinyPtrVector (and a NonOwningParsedAttributes is created to have a non-allocating attributes list). DeclaratorChunk gets the later kind, Declarator/DeclSpec keep ParsedAttributes.

Iterators are added to the ParsedAttribute types so that for-loops work.

Now for the bad news;
1- This is an insanely large patch. The refactor itself touches a ton of files.

Feedback/assistance would be greatly appreciated!
-Erich

[erichkeane]

The most interesting changes are in AttributeList.h. I also forgot to mention: I'd love to be more aggressive about the ownership semantics (in fact, my first 2 attempts were much stricter), however we make a lot of assumptions based on the ability to pass attribute lists between functions and have them modify on eachother. I'm hoping the tests that fail aren't too related to being able to modify the list for a different ParsedAttributes collection.

ALSO, I'd love to do the renaming of AttributeList to ParsedAttribute, but I just don't have the heart right now :)

[aaron.ballman]

Wow, this is an amazing start to a very large refactoring! Thank you for tackling this. I've made a few review comments but haven't gotten through the entire patch yet. The parts that I've seen all look reasonably sane thus far.

The most interesting changes are in AttributeList.h. I also forgot to mention: I'd love to be more aggressive about the ownership semantics (in fact, my first 2 attempts were much stricter), however we make a lot of assumptions based on the ability to pass attribute lists between functions and have them modify on eachother. I'm hoping the tests that fail aren't too related to being able to modify the list for a different ParsedAttributes collection.

One question that came to my mind is whether we should be attempting to add some better const correctness as part of this refactoring. This part of the code has always been unsatisfactory in that regard and I think the lack of const correctness is part of why the semantics here are as muddled as they are. If we add more const correctness, the patch is likely to grow even larger, but it may also point out the areas where we're doing something questionable when there's now a better way.

Given the massive nature of this patch, I can volunteer to handle the fit and finish comments rather than nag you to take care of them, if you'd like to tag team on the patch.

More review comments to come later. :-)

include/clang/Parse/Parser.h

2286–2287

Unrelated formatting changes?

2331

attrs -> Attrs

2333

isInvalid() instead of !isValid()

You could make the same change above as a drive-by.

include/clang/Sema/AttributeList.h

736–742

Do all of these need to be explicitly defaulted?

758–775

Why a custom iterator class instead of: using iterator = VecTy::iterator;?

778

Should probably spell out PA as ParsedAttribute

804

Can we have two overloads: AttributePool &getPool() and const AttributePool &getPool() const? I'm not keen on a const method exposing a non-const reference to an internal data structure.

806–811

Can be removed.

[erichkeane]

One question that came to my mind is whether we should be attempting to add some better const correctness as part of this refactoring. This part of the code has always been unsatisfactory in that regard and I think the lack of const correctness is part of why the semantics here are as muddled as they are. If we add more const correctness, the patch is likely to grow even larger, but it may also point out the areas where we're doing something questionable when there's now a better way.

I had a couple of false-starts where I attempted to be more const-correct, but it ends up breaking quite a bit of stuff, and I was overwhelmed. I suspect that once we have a somewhat functional version of this patch that we an add it piecemeal.

Given the massive nature of this patch, I can volunteer to handle the fit and finish comments rather than nag you to take care of them, if you'd like to tag team on the patch.

That would be wonderful! Last week was quite an adventure attempting this on my own, so any help I could possibly have would be greatly appreciated!

More review comments to come later. :-)

include/clang/Sema/AttributeList.h

736–742

Probably not, I got carried away with rule-of-5 I guess :)

758–775

VecTy has to hold a pointer, since the allocation is handled separately, however I intend for this type to appear to hold AttributeList directly. This iterator makes dereferencing an iterator cause an AttributeList& instead of an AttributeList*.

778

Woops! At one point I'd accidentally dropped a reference from an operator somewhere, and this was part of my diagnosis. I'll just delete it, since it is guaranteed by iterator_adaptor_base.

804

I don't think we can just yet... The pool is a mutable field, since sharing the allocator across a number of places is part of the existing design. For example, a function that handles declarator chunks would have a const-ref to its Declarator, but shouldn't modify it. HOWEVER, in order to create new attributes it needs to allocate on the Declarator's collection.

I'm not a huge fan of this design, but unfortunately, its what we have so far :/ I tried a couple of other ways to make allocation of these more sane than this, but quickly fell into traps with shared ownership.

[erichkeane]

Running through Aaron's first set of comments.

[erichkeane]

This patch rebases, since I didn't have @Meinersbur s revert. Additionally, I fix a couple of stupid errors, and get failure count down to 47!

All help is welcome :)

[Meinersbur]

Would it be possible (not in this patch) to consolidate the different lists of attributes: ParsedAttributes, AttributeFactory, AttributeList, AttributePool, NonOwningParsedAttributes, NonOwningParsedAttributesWithRange? Naively, expect to use something like std::vector<Attribute*>. Currently AttributeList can be a single attribute as well as a list of attributes.

include/clang/Sema/AttributeList.h

591–593

Is there another way than using a vector of vectors (of AttributeLists)?

IMHO the small size of 8 for the inner list is quite large: When the outer vector needs to grow, that many elements need to be copied (+ control structures).

[Please ignore me if it makes your work more difficult]

617

Thank you for working on this.

include/clang/Sema/DeclSpec.h

1545

Why does this have an additional AF parameter?

lib/Parse/ParseDeclCXX.cpp

3877–3879

It seems that from here on Attrs is interpreted as a single attribute. Did you consider storing Attrs.begin() into a Attr variable?

lib/Sema/SemaDeclAttr.cpp

5789

What is the reason to make this a method?

[erichkeane]

Fix things found by @Meinersbur

[erichkeane]

In D48788#1149657, @Meinersbur wrote:

Would it be possible (not in this patch) to consolidate the different lists of attributes: ParsedAttributes, AttributeFactory, AttributeList, AttributePool, NonOwningParsedAttributes, NonOwningParsedAttributesWithRange? Naively, expect to use something like std::vector<Attribute*>. Currently AttributeList can be a single attribute as well as a list of attributes.

So, each of those things has a distinct meaning unfortunately. AttributeFactory can very much be renamed "AttributeAllocator", because that is all that it is. "AttributePool" is basically an ownership/lifetime container of attributes, and uses the AttributeFactory to deallcoate them.

ParsedAttributes and NonOwningParsedAttributes I think need to stay separate for a while, the later is intended to replace "AttributeList*" (since it is a vector of AttributeList pointers). AttributeList will definitely be renamed at a point in the future.

The intent of this patch is to make it so that AttributeList is no longer used as a 'list' of attributes, simply a single attribute. I think I've successfully made that conversion in this patch.

include/clang/Sema/AttributeList.h

591–593

A different structure here is definitely possible. In the past, it was a linked list (Yes, AttributeList actually had TWO linked lists involved in it). I chose this to unblock the effort, but something a little more efficient might be nice.

That said, this is only allocated a single time and should almost never be resized. Additionally, there is only one AttributeFactory instance in the entire project.

include/clang/Sema/DeclSpec.h

1545

Woops! I guess I forgot to tear those out! A previous implementation I had was attempting to get lifetime-ownership semantics into DeclaratorChunk, but I realized that was too aggressive for this change. I'll revert these sections next time I have a chance.

lib/Sema/SemaDeclAttr.cpp

5789

ProcessDeclAttributeList was used in at least 1 spot (see change in SemaAttr.cpp) where it was intended to just process a single attribute. I made this a method so that it can be called in those locations.

[erichkeane]

All tests pass!

[Meinersbur]

In D48788#1150183, @erichkeane wrote:

All tests pass!

Very cool, thank you!

In D48100, @echristo mentioned that it broke test/Sema/attr-target-mv.c. No tests are changed here (so it's a NFC patch?), i.e. this is not fixed yet? The test case could be adapted by just changing the order of __vectorcall and __attribute__((target to emit the same message as before.

How do you intend to commit it? Just merging with D48100 into a single commit?

include/clang/Sema/AttributeList.h

777–778

According to the LLVM code style, parameter names start with capital letters.

[erichkeane]

In D48788#1150203, @Meinersbur wrote:

In D48788#1150183, @erichkeane wrote:

All tests pass!

Very cool, thank you!

In D48100, @echristo mentioned that it broke test/Sema/attr-target-mv.c. No tests are changed here (so it's a NFC patch?), i.e. this is not fixed yet? The test case could be adapted by just changing the order of __vectorcall and __attribute__((target to emit the same message as before.

How do you intend to commit it? Just merging with D48100 into a single commit?

I rebased this after the revert of D48100, so it is 'unbroken' now :) D48100 didn't actually break attr-target-mv.c, it just revealed a nasty side effect of the AttributeList linked-list behavior. Basically:
AttributeList objects were stored as a linked list in 3 places:
1- Declarator
2- DeclSpec
3- DeclaratorChunk

At one point during the process, we go through a bunch of attributes that apply to the function type and remove them from the declspec and put them on the declarator chunk. VectorCall is one of these attribute types. THEN, a RAII container's dtor re-adds them to the DeclSpec.

When they are at the end (pre D48100), this doesn't cause any issue, it ends up being at the end of both linked lists without issue. HOWEVER, when it was put at the FRONT (thanks to D48100), it actually has a 'Next' pointer that gets set as a part of the RAII destructor, resulting in things that are supposed to stay on the declspec appearing 2x, thus being SEMA'ed 2x. By removing the linked-list, we keep it so that only 'type' attributes get redistributed, then restored.

[erichkeane]

Forgot to answer this before:

How do you intend to commit it? Just merging with D48100 into a single commit?

I intend to commit this on its own, I think this patch stands on its own. I see this as simply unblocking the ability to recommit D48100, since it won't be breaking things that suffer from that failure.

[Meinersbur]

LGTM; however, since this is a relatively core change, maybe seek some more approvals.
Tests pass for me as well.

include/clang/Sema/AttributeList.h

900

[nit] unrelated whitespace change

lib/Sema/SemaType.cpp

605–607

[nit] unnecessary added braced

[erichkeane]

Thanks for the review! I fixed the two nits. I'm definitely going to wait for @aaron.ballman to give the final approval, he's promised me a slice of his time when he gets a chance :)

[aaron.ballman]

include/clang/Sema/AttributeList.h

600

Formatting and naming (don't name the argument Attr).

624

Why the name change here? I read this as somehow creating a new attribute and returning memory that is owned by the caller.

730–731

Would this be a ParsedAttributesView or some such? I'm wondering if "view" or "span" nomenclature would get rid of the awkwardness of "nonowning", but if you prefer the bikeshed with its current color, I'm not going to scream in pain.

741–745

I almost wonder if we should rename this to addAtStart()?

789–790

This signature excludes the ability to add from a const_iterator. Could either use a concrete type of iterator_adapter_base where the interesting type arguments are deduced, or could use a template type and pray/enable_if.

793–800

Ditto.

include/clang/Sema/DeclSpec.h

1152

I think this empty struct can go away entirely now, can't it?

2132–2134

So this is accepting attrs by rvalue reference only because it is expected to steal the resources from attr by taking everything from its pool? If so, that might be a good thing to put into the function comments; it's a bit subtle.

lib/Parse/ParseCXXInlineMethods.cpp

47–48

Spurious formatting change that isn't needed?

lib/Parse/ParseDecl.cpp

1611

How did you come up with 5? I would expect this to be like 1.

lib/Parse/ParseDeclCXX.cpp

2478

Should probably use empty parens for consistency with the rest of the expression.

2764

No longer need to check AccessAttrs.empty().

lib/Parse/ParseObjc.cpp

1202

Is there a benefit to doing this in two passes instead of looping in reverse order? e.g.,

for (const auto &AL : llvm::reverse(from)) {
  if (!AL.isUsedAsTypeAttr()) {
    from.remove(AL);
    attrs.add(AL);
  }
}

1866–1868

No need for the local here, just construct within the call expression.

lib/Parse/ParsePragma.cpp

1432–1433

Instead of calling Attrs.begin() multiple times, I think we should hoist this local variable up and use it when needed.

lib/Parse/ParseStmt.cpp

629–630

No need to check empty().

lib/Sema/DeclSpec.cpp

996–997

writtenBS.ModeAttr = llvm::any_of(getAttributes(), [](const auto &AL) { return AL.getKind() == AttributeList::AT_Mode; });

lib/Sema/SemaDecl.cpp

6205–6206

You can use llvm::any_of() here as well to turn this into a one-liner. Because it looks like this is only used once, it might be worth ditching entirely.

lib/Sema/SemaDeclAttr.cpp

5789

I think this is a lot of churn for one use case -- attributes are generally expected as groups (especially because all of the attribute syntaxes allow you to pass multiple attributes within the designating syntax) and exposing a public method to process a single attribute encourages people to forget that detail. Personally, I think this is better left as a static function, especially because public functions have a habit of having their parameter lists augmented and this is a situation we emphatically do not want that (we want ProcessDeclAttribute() to have the same signature as the handleFooAttr() functions because I have high hopes of scripting more of this away with tablegen magic someday.

6667

I don't believe we need to check empty() here any longer.

lib/Sema/SemaDeclCXX.cpp

2819–2826

Can the return type and argument type be brought into alignment in terms of their constness?

lib/Sema/SemaLambda.cpp

1173

Should probably switch to parens for consistency.

1600

Should probably switch to parens for consistency.

lib/Sema/SemaStmt.cpp

4286

Should probably switch to parens for consistency.

lib/Sema/SemaTemplateInstantiate.cpp

2128

Should probably switch to parens for consistency.

lib/Sema/SemaType.cpp

599

existin glist -> existing list

3997–4001

llvm::any_of?

4537–4538

llvm::any_of?

Honestly, I'm wondering if we want to add some inline helper free functions to AttributeList.h given how often we hit two different use cases. The two common ones seem to be "does this list contain an attribute of this kind?" and "get me the first attribute from this list with this kind".

5026–5028

llvm::any_of()?

5216

attrs -> Attrs

[erichkeane]

I think I got all of @aaron.ballman s comments.

include/clang/Sema/AttributeList.h

624

I thought it better reflected the usage, which is from 'createNew', this takes ownership. Though, I guess it should be pretty obvious since this is on AttributePool (and I can now see the alternate interpretation) so I'll change it back.

789–790

It seems to me just adding a second overload of each is more explicit and about the same amount of typing. I'll add those.

include/clang/Sema/DeclSpec.h

2132–2134

Thats exactly why. It steals ownership of them.

lib/Parse/ParseObjc.cpp

1202

I don't believe so. Likely just a leftover from the iterative conversion process where these were just forward iterators. Presumably SmallVector won't invalidate the iterators on removal in this situation?

[erichkeane]

@aaron.ballman any more feedback here? Or am I good to go?

[aaron.ballman]

LGTM! Thank you for doing this work, Erich!

include/clang/Parse/Parser.h

private:
   void PopParsingClass(Sema::ParsingClassState);
 
   enum CachedInitKind {
     CIK_DefaultArgument,
     CIK_DefaultInitializer
   };
 
   NamedDecl *ParseCXXInlineMethodDef(AccessSpecifier AS,
-                                AttributeList *AccessAttrs,
+                                     ParsedAttributes &AccessAttrs,
                                      ParsingDeclarator &D,
                                      const ParsedTemplateInfo &TemplateInfo,
-                                const VirtSpecifiers& VS,
+                                     const VirtSpecifiers &VS,
                                      SourceLocation PureSpecLoc);
   void ParseCXXNonStaticMemberInitializer(Decl *VarD);
   void ParseLexedAttributes(ParsingClass &Class);
   void ParseLexedAttributeList(LateParsedAttrList &LAs, Decl *D,
                                bool EnterScope, bool OnDefinition);
   void ParseLexedAttribute(LateParsedAttribute &LA,
                            bool EnterScope, bool OnDefinition);
   void ParseLexedMethodDeclarations(ParsingClass &Class);
   void ParseLexedMethodDeclaration(LateParsedMethodDeclaration &LM);
struct ParsedAttributesWithRange : ParsedAttributes {
 
     void clear() {
       ParsedAttributes::clear();
       Range = SourceRange();
     }
 
     SourceRange Range;
   };
+  struct ParsedAttributesViewWithRange : ParsedAttributesView {
+    ParsedAttributesViewWithRange() : ParsedAttributesView() {}
+    void clearListOnly() {
+      ParsedAttributesView::clearListOnly();
+      Range = SourceRange();
+    }
+
+    SourceRange Range;
+  };
 
   DeclGroupPtrTy ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
                                           ParsingDeclSpec *DS = nullptr);
   bool isDeclarationAfterDeclarator();
   bool isStartOfFunctionDefinition(const ParsingDeclarator &Declarator);
   DeclGroupPtrTy ParseDeclarationOrFunctionDefinition(
                                                   ParsedAttributesWithRange &attrs,
                                                   ParsingDeclSpec *DS = nullptr,
struct IfExistsCondition {
     /// should.
     IfExistsBehavior Behavior;
   };
 
   bool ParseMicrosoftIfExistsCondition(IfExistsCondition& Result);
   void ParseMicrosoftIfExistsStatement(StmtVector &Stmts);
   void ParseMicrosoftIfExistsExternalDeclaration();
   void ParseMicrosoftIfExistsClassDeclaration(DeclSpec::TST TagType,
-                                              AccessSpecifier& CurAS);
+                                              ParsedAttributes &AccessAttrs,
+                                              AccessSpecifier &CurAS);
   bool ParseMicrosoftIfExistsBraceInitializer(ExprVector &InitExprs,
                                               bool &InitExprsOk);
   bool ParseAsmOperandsOpt(SmallVectorImpl<IdentifierInfo *> &Names,
                            SmallVectorImpl<Expr *> &Constraints,
                            SmallVectorImpl<Expr *> &Exprs);
 
   //===--------------------------------------------------------------------===//
   // C++ 6: Statements and Blocks
private:
   TPResult TryConsumeDeclarationSpecifier();
 
 public:
   TypeResult ParseTypeName(SourceRange *Range = nullptr,
                            DeclaratorContext Context
                              = DeclaratorContext::TypeNameContext,
                            AccessSpecifier AS = AS_none,
                            Decl **OwnedType = nullptr,
                            ParsedAttributes *Attrs = nullptr);
 
 private:
   void ParseBlockId(SourceLocation CaretLoc);
 
   /// Are [[]] attributes enabled?
   bool standardAttributesAllowed() const {
     const LangOptions &LO = getLangOpts();
     return LO.DoubleSquareBracketAttributes;
   }
private:
   }
   void DiagnoseMisplacedCXX11Attribute(ParsedAttributesWithRange &Attrs,
                                        SourceLocation CorrectLocation);
 
   void stripTypeAttributesOffDeclSpec(ParsedAttributesWithRange &Attrs,
                                       DeclSpec &DS, Sema::TagUseKind TUK);
   
   // FixItLoc = possible correct location for the attributes
-  void ProhibitAttributes(ParsedAttributesWithRange &attrs,
+  void ProhibitAttributes(ParsedAttributesWithRange &Attrs,
                           SourceLocation FixItLoc = SourceLocation()) {
-    if (!attrs.Range.isValid()) return;
-    DiagnoseProhibitedAttributes(attrs, FixItLoc);
-    attrs.clear();
+    if (Attrs.Range.isInvalid())
+      return;
+    DiagnoseProhibitedAttributes(Attrs.Range, FixItLoc);
+    Attrs.clear();
   }
-  void DiagnoseProhibitedAttributes(ParsedAttributesWithRange &attrs, 
+
+  void ProhibitAttributes(ParsedAttributesViewWithRange &Attrs,
+                          SourceLocation FixItLoc = SourceLocation()) {
+    if (Attrs.Range.isInvalid())
+      return;
+    DiagnoseProhibitedAttributes(Attrs.Range, FixItLoc);
+    Attrs.clearListOnly();
+  }
+  void DiagnoseProhibitedAttributes(const SourceRange &Range,
                                     SourceLocation FixItLoc);
 
   // Forbid C++11 and C2x attributes that appear on certain syntactic locations
   // which standard permits but we don't supported yet, for example, attributes
   // appertain to decl specifiers.
   void ProhibitCXX11Attributes(ParsedAttributesWithRange &Attrs,
                                unsigned DiagID);
 
   /// Skip C++11 and C2x attributes and return the end location of the
ExprResult ParseCXXMemberInitializer(Decl *D, bool IsFunction,
                                        SourceLocation &EqualLoc);
   bool ParseCXXMemberDeclaratorBeforeInitializer(Declarator &DeclaratorInfo,
                                                  VirtSpecifiers &VS,
                                                  ExprResult &BitfieldSize,
                                                  LateParsedAttrList &LateAttrs);
   void MaybeParseAndDiagnoseDeclSpecAfterCXX11VirtSpecifierSeq(Declarator &D,
                                                                VirtSpecifiers &VS);
   DeclGroupPtrTy ParseCXXClassMemberDeclaration(
-      AccessSpecifier AS, AttributeList *Attr,
+      AccessSpecifier AS, ParsedAttributes &Attr,
       const ParsedTemplateInfo &TemplateInfo = ParsedTemplateInfo(),
       ParsingDeclRAIIObject *DiagsFromTParams = nullptr);
   DeclGroupPtrTy ParseCXXClassMemberDeclarationWithPragmas(
       AccessSpecifier &AS, ParsedAttributesWithRange &AccessAttrs,
       DeclSpec::TST TagType, Decl *Tag);
   void ParseConstructorInitializer(Decl *ConstructorDecl);
   MemInitResult ParseMemInitializer(Decl *ConstructorDecl);
   void HandleMemberFunctionDeclDelays(Declarator& DeclaratorInfo,
bool ParseUnqualifiedId(CXXScopeSpec &SS, bool EnteringContext,
                           UnqualifiedId &Result);
 
 private:
   //===--------------------------------------------------------------------===//
   // C++ 14: Templates [temp]
 
   // C++ 14.1: Template Parameters [temp.param]
   Decl *ParseDeclarationStartingWithTemplate(DeclaratorContext Context,
                                              SourceLocation &DeclEnd,
-                                          AccessSpecifier AS = AS_none,
-                                          AttributeList *AccessAttrs = nullptr);
+                                             ParsedAttributes &AccessAttrs,
+                                             AccessSpecifier AS = AS_none);
   Decl *ParseTemplateDeclarationOrSpecialization(DeclaratorContext Context,
                                                  SourceLocation &DeclEnd,
-                                                 AccessSpecifier AS,
-                                                 AttributeList *AccessAttrs);
+                                                 ParsedAttributes &AccessAttrs,
+                                                 AccessSpecifier AS);
   Decl *ParseSingleDeclarationAfterTemplate(
-                                       DeclaratorContext Context,
-                                       const ParsedTemplateInfo &TemplateInfo,
-                                       ParsingDeclRAIIObject &DiagsFromParams,
-                                       SourceLocation &DeclEnd,
-                                       AccessSpecifier AS=AS_none,
-                                       AttributeList *AccessAttrs = nullptr);
+      DeclaratorContext Context, const ParsedTemplateInfo &TemplateInfo,
+      ParsingDeclRAIIObject &DiagsFromParams, SourceLocation &DeclEnd,
+      ParsedAttributes &AccessAttrs, AccessSpecifier AS = AS_none);
   bool ParseTemplateParameters(unsigned Depth,
                                SmallVectorImpl<NamedDecl *> &TemplateParams,
                                SourceLocation &LAngleLoc,
                                SourceLocation &RAngleLoc);
   bool ParseTemplateParameterList(unsigned Depth,
                                   SmallVectorImpl<NamedDecl*> &TemplateParams);
   bool isStartOfTemplateTypeParameter();
   NamedDecl *ParseTemplateParameter(unsigned Depth, unsigned Position);
private:
   bool IsTemplateArgumentList(unsigned Skip = 0);
   bool ParseTemplateArgumentList(TemplateArgList &TemplateArgs);
   ParsedTemplateArgument ParseTemplateTemplateArgument();
   ParsedTemplateArgument ParseTemplateArgument();
   Decl *ParseExplicitInstantiation(DeclaratorContext Context,
                                    SourceLocation ExternLoc,
                                    SourceLocation TemplateLoc,
                                    SourceLocation &DeclEnd,
+                                   ParsedAttributes &AccessAttrs,
                                    AccessSpecifier AS = AS_none);
 
   //===--------------------------------------------------------------------===//
   // Modules
   DeclGroupPtrTy ParseModuleDecl();
   Decl *ParseModuleImport(SourceLocation AtLoc);
   bool parseMisplacedModuleImport();
   bool tryParseMisplacedModuleImport() {

include/clang/Sema/AttributeList.h

 #define LLVM_CLANG_SEMA_ATTRIBUTELIST_H
 
 #include "clang/Basic/AttrSubjectMatchRules.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/TargetInfo.h"
 #include "clang/Sema/Ownership.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/TinyPtrVector.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/VersionTuple.h"
 #include <cassert>
 #include <cstddef>
 #include <cstring>
 #include <utility>
 
 namespace clang {
private:
   mutable unsigned ProcessingCache : 8;
 
   /// The location of the 'unavailable' keyword in an
   /// availability attribute.
   SourceLocation UnavailableLoc;
   
   const Expr *MessageExpr;
 
-  /// The next attribute in the current position.
-  AttributeList *NextInPosition = nullptr;
-
-  /// The next attribute allocated in the current Pool.
-  AttributeList *NextInPool = nullptr;
-
   /// Arguments, if any, are stored immediately following the object.
   ArgsUnion *getArgsBuffer() { return reinterpret_cast<ArgsUnion *>(this + 1); }
   ArgsUnion const *getArgsBuffer() const {
     return reinterpret_cast<ArgsUnion const *>(this + 1);
   }
 
   /// Availability information is stored immediately following the arguments,
   /// if any, at the end of the object.
public:
 
   bool isPackExpansion() const { return EllipsisLoc.isValid(); }
   SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
 
   Kind getKind() const { return Kind(AttrKind); }
   static Kind getKind(const IdentifierInfo *Name, const IdentifierInfo *Scope,
                       Syntax SyntaxUsed);
 
-  AttributeList *getNext() const { return NextInPosition; }
-  void setNext(AttributeList *N) { NextInPosition = N; }
-
   /// getNumArgs - Return the number of actual arguments to this attribute.
   unsigned getNumArgs() const { return NumArgs; }
 
   /// getArg - Return the specified argument.
   ArgsUnion getArg(unsigned Arg) const {
     assert(Arg < NumArgs && "Arg access out of range!");
     return getArgsBuffer()[Arg];
   }
public:
   /// If the parsed attribute has a semantic equivalent, and it would
   /// have a semantic Spelling enumeration (due to having semantically-distinct
   /// spelling variations), return the value of that semantic spelling. If the
   /// parsed attribute does not have a semantic equivalent, or would not have
   /// a Spelling enumeration, the value UINT_MAX is returned.
   unsigned getSemanticSpelling() const;
 };
 
+class AttributePool;
 /// A factory, from which one makes pools, from which one creates
 /// individual attributes which are deallocated with the pool.
 ///
 /// Note that it's tolerably cheap to create and destroy one of
 /// these as long as you don't actually allocate anything in it.
 class AttributeFactory {
 public:
   enum {
enum {
     InlineFreeListsCapacity =
       1 + (AvailabilityAllocSize - sizeof(AttributeList)) / sizeof(void*)
   };
 
   llvm::BumpPtrAllocator Alloc;
 
   /// Free lists.  The index is determined by the following formula:
   ///   (size - sizeof(AttributeList)) / sizeof(void*)
-  SmallVector<AttributeList*, InlineFreeListsCapacity> FreeLists;
+  SmallVector<SmallVector<AttributeList *, 8>, InlineFreeListsCapacity>
+      FreeLists;
 
   // The following are the private interface used by AttributePool.
   friend class AttributePool;
 
   /// Allocate an attribute of the given size.
   void *allocate(size_t size);
 
+  void deallocate(AttributeList *AL);
+
   /// Reclaim all the attributes in the given pool chain, which is
   /// non-empty.  Note that the current implementation is safe
   /// against reclaiming things which were not actually allocated
   /// with the allocator, although of course it's important to make
   /// sure that their allocator lives at least as long as this one.
-  void reclaimPool(AttributeList *head);
+  void reclaimPool(AttributePool &head);
 
 public:
   AttributeFactory();
   ~AttributeFactory();
 };
 
 class AttributePool {
+  friend class AttributeFactory;
   AttributeFactory &Factory;
-  AttributeList *Head = nullptr;
+  llvm::TinyPtrVector<AttributeList *> Attrs;
 
   void *allocate(size_t size) {
     return Factory.allocate(size);
   }
 
   AttributeList *add(AttributeList *attr) {
-    // We don't care about the order of the pool.
-    attr->NextInPool = Head;
-    Head = attr;
+    Attrs.push_back(attr);
     return attr;
   }
 
-  void takePool(AttributeList *pool);
+  void remove(AttributeList *attr) {
+    assert(llvm::is_contained(Attrs, attr) &&
+           "Can't take attribute from a pool that doesn't own it!");
+    Attrs.erase(llvm::find(Attrs, attr));
+  }
+
+  void takePool(AttributePool &pool);
 
 public:
   /// Create a new pool for a factory.
   AttributePool(AttributeFactory &factory) : Factory(factory) {}
 
   AttributePool(const AttributePool &) = delete;
 
-  ~AttributePool() {
-    if (Head) Factory.reclaimPool(Head);
-  }
+  ~AttributePool() { Factory.reclaimPool(*this); }
 
   /// Move the given pool's allocations to this pool.
-  AttributePool(AttributePool &&pool) : Factory(pool.Factory), Head(pool.Head) {
-    pool.Head = nullptr;
-  }
+  AttributePool(AttributePool &&pool) = default;
 
   AttributeFactory &getFactory() const { return Factory; }
 
   void clear() {
-    if (Head) {
-      Factory.reclaimPool(Head);
-      Head = nullptr;
-    }
+    Factory.reclaimPool(*this);
+    Attrs.clear();
   }
 
   /// Take the given pool's allocations and add them to this pool.
   void takeAllFrom(AttributePool &pool) {
-    if (pool.Head) {
-      takePool(pool.Head);
-      pool.Head = nullptr;
-    }
+    takePool(pool);
+    pool.Attrs.clear();
   }
 
   AttributeList *create(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         ArgsUnion *args, unsigned numArgs,
                         AttributeList::Syntax syntax,
                         SourceLocation ellipsisLoc = SourceLocation()) {
-    void *memory = allocate(sizeof(AttributeList)
-                            + numArgs * sizeof(ArgsUnion));
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          args, numArgs, syntax,
-                                          ellipsisLoc));
+    void *memory =
+        allocate(sizeof(AttributeList) + numArgs * sizeof(ArgsUnion));
+    return add(new (memory)
+                   AttributeList(attrName, attrRange, scopeName, scopeLoc, args,
+                                 numArgs, syntax, ellipsisLoc));
   }
 
   AttributeList *create(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         IdentifierLoc *Param,
                         const AvailabilityChange &introduced,
                         const AvailabilityChange &deprecated,
                         const AvailabilityChange &obsoleted,
-                        SourceLocation unavailable,
-                        const Expr *MessageExpr,
-                        AttributeList::Syntax syntax,
-                        SourceLocation strict, const Expr *ReplacementExpr) {
+                        SourceLocation unavailable, const Expr *MessageExpr,
+                        AttributeList::Syntax syntax, SourceLocation strict,
+                        const Expr *ReplacementExpr) {
     void *memory = allocate(AttributeFactory::AvailabilityAllocSize);
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          Param, introduced, deprecated,
-                                          obsoleted, unavailable, MessageExpr,
-                                          syntax, strict, ReplacementExpr));
+    return add(new (memory) AttributeList(
+        attrName, attrRange, scopeName, scopeLoc, Param, introduced, deprecated,
+        obsoleted, unavailable, MessageExpr, syntax, strict, ReplacementExpr));
   }
 
   AttributeList *create(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
-                        IdentifierLoc *Param1,
-                        IdentifierLoc *Param2,
-                        IdentifierLoc *Param3,
-                        AttributeList::Syntax syntax) {
+                        IdentifierLoc *Param1, IdentifierLoc *Param2,
+                        IdentifierLoc *Param3, AttributeList::Syntax syntax) {
     size_t size = sizeof(AttributeList) + 3 * sizeof(ArgsUnion);
     void *memory = allocate(size);
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          Param1, Param2, Param3,
-                                          syntax));
+    return add(new (memory)
+                   AttributeList(attrName, attrRange, scopeName, scopeLoc,
+                                 Param1, Param2, Param3, syntax));
   }
 
-  AttributeList *createTypeTagForDatatype(
-                    IdentifierInfo *attrName, SourceRange attrRange,
+  AttributeList *
+  createTypeTagForDatatype(IdentifierInfo *attrName, SourceRange attrRange,
                            IdentifierInfo *scopeName, SourceLocation scopeLoc,
-                    IdentifierLoc *argumentKind, ParsedType matchingCType,
-                    bool layoutCompatible, bool mustBeNull,
-                    AttributeList::Syntax syntax) {
+                           IdentifierLoc *argumentKind,
+                           ParsedType matchingCType, bool layoutCompatible,
+                           bool mustBeNull, AttributeList::Syntax syntax) {
     void *memory = allocate(AttributeFactory::TypeTagForDatatypeAllocSize);
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          argumentKind, matchingCType,
-                                          layoutCompatible, mustBeNull,
-                                          syntax));
+    return add(new (memory) AttributeList(
+        attrName, attrRange, scopeName, scopeLoc, argumentKind, matchingCType,
+        layoutCompatible, mustBeNull, syntax));
   }
 
-  AttributeList *createTypeAttribute(
-                    IdentifierInfo *attrName, SourceRange attrRange,
+  AttributeList *
+  createTypeAttribute(IdentifierInfo *attrName, SourceRange attrRange,
                       IdentifierInfo *scopeName, SourceLocation scopeLoc,
                       ParsedType typeArg, AttributeList::Syntax syntaxUsed) {
     void *memory = allocate(sizeof(AttributeList) + sizeof(void *));
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          typeArg, syntaxUsed));
+    return add(new (memory) AttributeList(attrName, attrRange, scopeName,
+                                          scopeLoc, typeArg, syntaxUsed));
   }
 
-  AttributeList *createPropertyAttribute(
-                    IdentifierInfo *attrName, SourceRange attrRange,
+  AttributeList *
+  createPropertyAttribute(IdentifierInfo *attrName, SourceRange attrRange,
                           IdentifierInfo *scopeName, SourceLocation scopeLoc,
                           IdentifierInfo *getterId, IdentifierInfo *setterId,
                           AttributeList::Syntax syntaxUsed) {
     void *memory = allocate(AttributeFactory::PropertyAllocSize);
-    return add(new (memory) AttributeList(attrName, attrRange,
-                                          scopeName, scopeLoc,
-                                          getterId, setterId,
-                                          syntaxUsed));
+    return add(new (memory)
+                   AttributeList(attrName, attrRange, scopeName, scopeLoc,
+                                 getterId, setterId, syntaxUsed));
   }
 };
 
-/// ParsedAttributes - A collection of parsed attributes.  Currently
-/// we don't differentiate between the various attribute syntaxes,
-/// which is basically silly.
-///
-/// Right now this is a very lightweight container, but the expectation
-/// is that this will become significantly more serious.
-class ParsedAttributes {
-public:
-  ParsedAttributes(AttributeFactory &factory) : pool(factory) {}
-  ParsedAttributes(const ParsedAttributes &) = delete;
-
-  AttributePool &getPool() const { return pool; }
+class ParsedAttributesView {
+  using VecTy = llvm::TinyPtrVector<AttributeList *>;
+  using SizeType = decltype(std::declval<VecTy>().size());
 
-  bool empty() const { return list == nullptr; }
+public:
+  bool empty() const { return AttrList.empty(); }
+  SizeType size() const { return AttrList.size(); }
+  AttributeList &operator[](SizeType pos) { return *AttrList[pos]; }
+  const AttributeList &operator[](SizeType pos) const { return *AttrList[pos]; }
 
-  void add(AttributeList *newAttr) {
+  void addAtStart(AttributeList *newAttr) {
     assert(newAttr);
-    assert(newAttr->getNext() == nullptr);
-    newAttr->setNext(list);
-    list = newAttr;
+    AttrList.insert(AttrList.begin(), newAttr);
+  }
+  void addAtEnd(AttributeList *newAttr) {
+    assert(newAttr);
+    AttrList.push_back(newAttr);
   }
 
-  void addAll(AttributeList *newList) {
-    if (!newList) return;
+  void remove(AttributeList *ToBeRemoved) {
+    assert(is_contained(AttrList, ToBeRemoved) &&
+           "Cannot remove attribute that isn't in the list");
+    AttrList.erase(llvm::find(AttrList, ToBeRemoved));
+  }
 
-    AttributeList *lastInNewList = newList;
-    while (AttributeList *next = lastInNewList->getNext())
-      lastInNewList = next;
+  void clearListOnly() { AttrList.clear(); }
 
-    lastInNewList->setNext(list);
-    list = newList;
+  struct iterator : llvm::iterator_adaptor_base<iterator, VecTy::iterator,
+                                                std::random_access_iterator_tag,
+                                                AttributeList> {
+    iterator() : iterator_adaptor_base(nullptr) {}
+    iterator(VecTy::iterator I) : iterator_adaptor_base(I) {}
+    reference operator*() { return **I; }
+    friend class ParsedAttributesView;
+  };
+  struct const_iterator
+      : llvm::iterator_adaptor_base<const_iterator, VecTy::const_iterator,
+                                    std::random_access_iterator_tag,
+                                    AttributeList> {
+    const_iterator() : iterator_adaptor_base(nullptr) {}
+    const_iterator(VecTy::const_iterator I) : iterator_adaptor_base(I) {}
+
+    reference operator*() const { return **I; }
+    friend class ParsedAttributesView;
+  };
+
+  void addAll(iterator B, iterator E) {
+    AttrList.insert(AttrList.begin(), B.I, E.I);
   }
 
-  void addAllAtEnd(AttributeList *newList) {
-    if (!list) {
-      list = newList;
-      return;
-    }
+  void addAll(const_iterator B, const_iterator E) {
+    AttrList.insert(AttrList.begin(), B.I, E.I);
 
-    AttributeList *lastInList = list;
-    while (AttributeList *next = lastInList->getNext())
-      lastInList = next;
+  void addAllAtEnd(iterator B, iterator E) {
+    AttrList.insert(AttrList.end(), B.I, E.I);
+  }
 
-    lastInList->setNext(newList);
+  void addAllAtEnd(const_iterator B, const_iterator E) {
+    AttrList.insert(AttrList.end(), B.I, E.I);
   }
 
-  void set(AttributeList *newList) {
-    list = newList;
+  iterator begin() { return iterator(AttrList.begin()); }
+  const_iterator begin() const { return const_iterator(AttrList.begin()); }
+  iterator end() { return iterator(AttrList.end()); }
+  const_iterator end() const { return const_iterator(AttrList.end()); }
+
+  bool hasAttribute(AttributeList::Kind K) const {
+    return llvm::any_of(
+        AttrList, [K](const AttributeList *AL) { return AL->getKind() == K; });
   }
 
+private:
+  VecTy AttrList;
+};
+
+/// ParsedAttributes - A collection of parsed attributes.  Currently
+/// we don't differentiate between the various attribute syntaxes,
+/// which is basically silly.
+///
+/// Right now this is a very lightweight container, but the expectation
+/// is that this will become significantly more serious.
+class ParsedAttributes : public ParsedAttributesView {
+public:
+  ParsedAttributes(AttributeFactory &factory) : pool(factory) {}
+  ParsedAttributes(const ParsedAttributes &) = delete;
+
+  AttributePool &getPool() const { return pool; }
+
   void takeAllFrom(ParsedAttributes &attrs) {
-    addAll(attrs.list);
-    attrs.list = nullptr;
+    addAll(attrs.begin(), attrs.end());
+    attrs.clearListOnly();
     pool.takeAllFrom(attrs.pool);
   }
 
-  void clear() { list = nullptr; pool.clear(); }
-  AttributeList *getList() const { return list; }
-
-  void clearListOnly() { list = nullptr; }
-
-  /// Returns a reference to the attribute list.  Try not to introduce
-  /// dependencies on this method, it may not be long-lived.
-  AttributeList *&getListRef() { return list; }
+  void clear() {
+    clearListOnly();
+    pool.clear();
+  }
 
   /// Add attribute with expression arguments.
   AttributeList *addNew(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         ArgsUnion *args, unsigned numArgs,
                         AttributeList::Syntax syntax,
                         SourceLocation ellipsisLoc = SourceLocation()) {
     AttributeList *attr =
       pool.create(attrName, attrRange, scopeName, scopeLoc, args, numArgs,
                   syntax, ellipsisLoc);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
   /// Add availability attribute.
   AttributeList *addNew(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         IdentifierLoc *Param,
                         const AvailabilityChange &introduced,
                         const AvailabilityChange &deprecated,
                         const AvailabilityChange &obsoleted,
                         SourceLocation unavailable,
                         const Expr *MessageExpr,
                         AttributeList::Syntax syntax,
                         SourceLocation strict, const Expr *ReplacementExpr) {
     AttributeList *attr =
       pool.create(attrName, attrRange, scopeName, scopeLoc, Param, introduced,
                   deprecated, obsoleted, unavailable, MessageExpr, syntax,
                   strict, ReplacementExpr);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
   /// Add objc_bridge_related attribute.
   AttributeList *addNew(IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         IdentifierLoc *Param1,
                         IdentifierLoc *Param2,
                         IdentifierLoc *Param3,
                         AttributeList::Syntax syntax) {
     AttributeList *attr =
       pool.create(attrName, attrRange, scopeName, scopeLoc,
                   Param1, Param2, Param3, syntax);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
   /// Add type_tag_for_datatype attribute.
   AttributeList *addNewTypeTagForDatatype(
                         IdentifierInfo *attrName, SourceRange attrRange,
                         IdentifierInfo *scopeName, SourceLocation scopeLoc,
                         IdentifierLoc *argumentKind, ParsedType matchingCType,
                         bool layoutCompatible, bool mustBeNull,
                         AttributeList::Syntax syntax) {
     AttributeList *attr =
       pool.createTypeTagForDatatype(attrName, attrRange,
                                     scopeName, scopeLoc,
                                     argumentKind, matchingCType,
                                     layoutCompatible, mustBeNull, syntax);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
   /// Add an attribute with a single type argument.
   AttributeList *
   addNewTypeAttr(IdentifierInfo *attrName, SourceRange attrRange,
                  IdentifierInfo *scopeName, SourceLocation scopeLoc,
                  ParsedType typeArg, AttributeList::Syntax syntaxUsed) {
     AttributeList *attr =
         pool.createTypeAttribute(attrName, attrRange, scopeName, scopeLoc,
                                  typeArg, syntaxUsed);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
   /// Add microsoft __delspec(property) attribute.
   AttributeList *
   addNewPropertyAttr(IdentifierInfo *attrName, SourceRange attrRange,
                  IdentifierInfo *scopeName, SourceLocation scopeLoc,
                  IdentifierInfo *getterId, IdentifierInfo *setterId,
                  AttributeList::Syntax syntaxUsed) {
     AttributeList *attr =
         pool.createPropertyAttribute(attrName, attrRange, scopeName, scopeLoc,
                                      getterId, setterId, syntaxUsed);
-    add(attr);
+    addAtStart(attr);
     return attr;
   }
 
 private:
   mutable AttributePool pool;
-  AttributeList *list = nullptr;
 };
 
 /// These constants match the enumerated choices of
 /// err_attribute_argument_n_type and err_attribute_argument_type.
 enum AttributeArgumentNType {
   AANT_ArgumentIntOrBool,
   AANT_ArgumentIntegerConstant,
   AANT_ArgumentString,

include/clang/Sema/DeclSpec.h

public:
   /// This declares 4 attributes using 2 lists. The following syntax is
   /// also allowed and equivalent to the previous declaration.
   ///
   /// \code
   /// short __attribute__((unused)) __attribute__((deprecated))
   /// int __attribute__((may_alias)) __attribute__((aligned(16))) var;
   /// \endcode
   ///
-  void addAttributes(AttributeList *AL) {
-    Attrs.addAll(AL);
+  void addAttributes(ParsedAttributesView &AL) {
+    Attrs.addAll(AL.begin(), AL.end());
   }
 
   bool hasAttributes() const { return !Attrs.empty(); }
 
   ParsedAttributes &getAttributes() { return Attrs; }
   const ParsedAttributes &getAttributes() const { return Attrs; }
 
   void takeAttributesFrom(ParsedAttributes &attrs) {
struct DeclaratorChunk {
   SourceLocation EndLoc;
 
   SourceRange getSourceRange() const {
     if (EndLoc.isInvalid())
       return SourceRange(Loc, Loc);
     return SourceRange(Loc, EndLoc);
   }
 
-  struct TypeInfoCommon {
-    AttributeList *AttrList;
-  };
+  ParsedAttributesView AttrList;
 
-  struct PointerTypeInfo : TypeInfoCommon {
+  struct PointerTypeInfo {
     /// The type qualifiers: const/volatile/restrict/unaligned/atomic.
     unsigned TypeQuals : 5;
 
     /// The location of the const-qualifier, if any.
     unsigned ConstQualLoc;
 
     /// The location of the volatile-qualifier, if any.
     unsigned VolatileQualLoc;
 
     /// The location of the restrict-qualifier, if any.
     unsigned RestrictQualLoc;
 
     /// The location of the _Atomic-qualifier, if any.
     unsigned AtomicQualLoc;
 
     /// The location of the __unaligned-qualifier, if any.
     unsigned UnalignedQualLoc;
 
     void destroy() {
     }
   };
 
-  struct ReferenceTypeInfo : TypeInfoCommon {
+  struct ReferenceTypeInfo {
     /// The type qualifier: restrict. [GNU] C++ extension
     bool HasRestrict : 1;
     /// True if this is an lvalue reference, false if it's an rvalue reference.
     bool LValueRef : 1;
     void destroy() {
     }
   };
 
-  struct ArrayTypeInfo : TypeInfoCommon {
+  struct ArrayTypeInfo {
     /// The type qualifiers for the array:
     /// const/volatile/restrict/__unaligned/_Atomic.
     unsigned TypeQuals : 5;
 
     /// True if this dimension included the 'static' keyword.
     unsigned hasStatic : 1;
 
     /// True if this dimension was [*].  In this case, NumElts is null.
ParamInfo(IdentifierInfo *ident, SourceLocation iloc,
         DefaultArgTokens(std::move(DefArgTokens)) {}
   };
 
   struct TypeAndRange {
     ParsedType Ty;
     SourceRange Range;
   };
 
-  struct FunctionTypeInfo : TypeInfoCommon {
+  struct FunctionTypeInfo {
     /// hasPrototype - This is true if the function had at least one typed
     /// parameter.  If the function is () or (a,b,c), then it has no prototype,
     /// and is treated as a K&R-style function.
     unsigned hasPrototype : 1;
 
     /// isVariadic - If this function has a prototype, and if that
     /// proto ends with ',...)', this is true. When true, EllipsisLoc
     /// contains the location of the ellipsis.
struct FunctionTypeInfo {
     /// Determine whether this function declarator had a
     /// trailing-return-type.
     bool hasTrailingReturnType() const { return HasTrailingReturnType; }
 
     /// Get the trailing-return-type for this function declarator.
     ParsedType getTrailingReturnType() const { return TrailingReturnType; }
   };
 
-  struct BlockPointerTypeInfo : TypeInfoCommon {
+  struct BlockPointerTypeInfo {
     /// For now, sema will catch these as invalid.
     /// The type qualifiers: const/volatile/restrict/__unaligned/_Atomic.
     unsigned TypeQuals : 5;
 
     void destroy() {
     }
   };
 
-  struct MemberPointerTypeInfo : TypeInfoCommon {
+  struct MemberPointerTypeInfo {
     /// The type qualifiers: const/volatile/restrict/__unaligned/_Atomic.
     unsigned TypeQuals : 5;
     // CXXScopeSpec has a constructor, so it can't be a direct member.
     // So we need some pointer-aligned storage and a bit of trickery.
     alignas(CXXScopeSpec) char ScopeMem[sizeof(CXXScopeSpec)];
     CXXScopeSpec &Scope() {
       return *reinterpret_cast<CXXScopeSpec *>(ScopeMem);
     }
     const CXXScopeSpec &Scope() const {
       return *reinterpret_cast<const CXXScopeSpec *>(ScopeMem);
     }
     void destroy() {
       Scope().~CXXScopeSpec();
     }
   };
 
-  struct PipeTypeInfo : TypeInfoCommon {
+  struct PipeTypeInfo {
     /// The access writes.
     unsigned AccessWrites : 3;
 
     void destroy() {}
   };
 
   union {
-    TypeInfoCommon        Common;
     PointerTypeInfo       Ptr;
     ReferenceTypeInfo     Ref;
     ArrayTypeInfo         Arr;
     FunctionTypeInfo      Fun;
     BlockPointerTypeInfo  Cls;
     MemberPointerTypeInfo Mem;
     PipeTypeInfo          PipeInfo;
   };
 
   void destroy() {
     switch (Kind) {
     case DeclaratorChunk::Function:      return Fun.destroy();
     case DeclaratorChunk::Pointer:       return Ptr.destroy();
     case DeclaratorChunk::BlockPointer:  return Cls.destroy();
     case DeclaratorChunk::Reference:     return Ref.destroy();
     case DeclaratorChunk::Array:         return Arr.destroy();
     case DeclaratorChunk::MemberPointer: return Mem.destroy();
     case DeclaratorChunk::Paren:         return;
     case DeclaratorChunk::Pipe:          return PipeInfo.destroy();
     }
   }
 
   /// If there are attributes applied to this declaratorchunk, return
   /// them.
-  const AttributeList *getAttrs() const {
-    return Common.AttrList;
-  }
-
-  AttributeList *&getAttrListRef() {
-    return Common.AttrList;
-  }
+  const ParsedAttributesView &getAttrs() const { return AttrList; }
+  ParsedAttributesView &getAttrs() { return AttrList; }
 
   /// Return a DeclaratorChunk for a pointer.
   static DeclaratorChunk getPointer(unsigned TypeQuals, SourceLocation Loc,
                                     SourceLocation ConstQualLoc,
                                     SourceLocation VolatileQualLoc,
                                     SourceLocation RestrictQualLoc,
                                     SourceLocation AtomicQualLoc,
                                     SourceLocation UnalignedQualLoc) {
     DeclaratorChunk I;
     I.Kind                = Pointer;
     I.Loc                 = Loc;
     I.Ptr.TypeQuals       = TypeQuals;
     I.Ptr.ConstQualLoc    = ConstQualLoc.getRawEncoding();
     I.Ptr.VolatileQualLoc = VolatileQualLoc.getRawEncoding();
     I.Ptr.RestrictQualLoc = RestrictQualLoc.getRawEncoding();
     I.Ptr.AtomicQualLoc   = AtomicQualLoc.getRawEncoding();
     I.Ptr.UnalignedQualLoc = UnalignedQualLoc.getRawEncoding();
-    I.Ptr.AttrList        = nullptr;
     return I;
   }
 
   /// Return a DeclaratorChunk for a reference.
   static DeclaratorChunk getReference(unsigned TypeQuals, SourceLocation Loc,
                                       bool lvalue) {
     DeclaratorChunk I;
     I.Kind            = Reference;
     I.Loc             = Loc;
     I.Ref.HasRestrict = (TypeQuals & DeclSpec::TQ_restrict) != 0;
     I.Ref.LValueRef   = lvalue;
-    I.Ref.AttrList    = nullptr;
     return I;
   }
 
   /// Return a DeclaratorChunk for an array.
   static DeclaratorChunk getArray(unsigned TypeQuals,
                                   bool isStatic, bool isStar, Expr *NumElts,
                                   SourceLocation LBLoc, SourceLocation RBLoc) {
     DeclaratorChunk I;
     I.Kind          = Array;
     I.Loc           = LBLoc;
     I.EndLoc        = RBLoc;
-    I.Arr.AttrList  = nullptr;
     I.Arr.TypeQuals = TypeQuals;
     I.Arr.hasStatic = isStatic;
     I.Arr.isStar    = isStar;
     I.Arr.NumElts   = NumElts;
     return I;
   }
 
   /// DeclaratorChunk::getFunction - Return a DeclaratorChunk for a function.
struct DeclaratorChunk {
 
   /// Return a DeclaratorChunk for a block.
   static DeclaratorChunk getBlockPointer(unsigned TypeQuals,
                                          SourceLocation Loc) {
     DeclaratorChunk I;
     I.Kind          = BlockPointer;
     I.Loc           = Loc;
     I.Cls.TypeQuals = TypeQuals;
-    I.Cls.AttrList  = nullptr;
     return I;
   }
 
   /// Return a DeclaratorChunk for a block.
   static DeclaratorChunk getPipe(unsigned TypeQuals,
                                  SourceLocation Loc) {
     DeclaratorChunk I;
     I.Kind          = Pipe;
     I.Loc           = Loc;
     I.Cls.TypeQuals = TypeQuals;
-    I.Cls.AttrList  = nullptr;
     return I;
   }
 
   static DeclaratorChunk getMemberPointer(const CXXScopeSpec &SS,
                                           unsigned TypeQuals,
                                           SourceLocation Loc) {
     DeclaratorChunk I;
     I.Kind          = MemberPointer;
     I.Loc           = SS.getBeginLoc();
     I.EndLoc        = Loc;
     I.Mem.TypeQuals = TypeQuals;
-    I.Mem.AttrList  = nullptr;
     new (I.Mem.ScopeMem) CXXScopeSpec(SS);
     return I;
   }
 
   /// Return a DeclaratorChunk for a paren.
   static DeclaratorChunk getParen(SourceLocation LParenLoc,
                                   SourceLocation RParenLoc) {
     DeclaratorChunk I;
     I.Kind          = Paren;
     I.Loc           = LParenLoc;
     I.EndLoc        = RParenLoc;
-    I.Common.AttrList = nullptr;
     return I;
   }
 
   bool isParen() const {
     return Kind == Paren;
   }
 };
 
public:
   /// Set the decomposition bindings for this declarator.
   void
   setDecompositionBindings(SourceLocation LSquareLoc,
                            ArrayRef<DecompositionDeclarator::Binding> Bindings,
                            SourceLocation RSquareLoc);
 
   /// AddTypeInfo - Add a chunk to this declarator. Also extend the range to
   /// EndLoc, which should be the last token of the chunk.
-  void AddTypeInfo(const DeclaratorChunk &TI,
-                   ParsedAttributes &attrs,
+  /// This function takes attrs by R-Value reference because it takes ownership
+  /// of those attributes from the parameter.
+  void AddTypeInfo(const DeclaratorChunk &TI, ParsedAttributes &&attrs,
                    SourceLocation EndLoc) {
     DeclTypeInfo.push_back(TI);
-    DeclTypeInfo.back().getAttrListRef() = attrs.getList();
+    DeclTypeInfo.back().getAttrs().addAll(attrs.begin(), attrs.end());
     getAttributePool().takeAllFrom(attrs.getPool());
 
     if (!EndLoc.isInvalid())
       SetRangeEnd(EndLoc);
   }
 
+  /// AddTypeInfo - Add a chunk to this declarator. Also extend the range to
+  /// EndLoc, which should be the last token of the chunk.
+  void AddTypeInfo(const DeclaratorChunk &TI, SourceLocation EndLoc) {
+    DeclTypeInfo.push_back(TI);
+
+    if (!EndLoc.isInvalid())
+      SetRangeEnd(EndLoc);
+  }
+
   /// Add a new innermost chunk to this declarator.
   void AddInnermostTypeInfo(const DeclaratorChunk &TI) {
     DeclTypeInfo.insert(DeclTypeInfo.begin(), TI);
   }
 
   /// Return the number of types applied to this declarator.
   unsigned getNumTypeObjects() const { return DeclTypeInfo.size(); }
 
public:
   /// Also extends the range of the declarator.
   void takeAttributes(ParsedAttributes &attrs, SourceLocation lastLoc) {
     Attrs.takeAllFrom(attrs);
 
     if (!lastLoc.isInvalid())
       SetRangeEnd(lastLoc);
   }
 
-  const AttributeList *getAttributes() const { return Attrs.getList(); }
-  AttributeList *getAttributes() { return Attrs.getList(); }
-
-  AttributeList *&getAttrListRef() { return Attrs.getListRef(); }
+  const ParsedAttributes &getAttributes() const { return Attrs; }
+  ParsedAttributes &getAttributes() { return Attrs; }
 
   /// hasAttributes - do we contain any attributes?
   bool hasAttributes() const {
-    if (getAttributes() || getDeclSpec().hasAttributes()) return true;
+    if (!getAttributes().empty() || getDeclSpec().hasAttributes())
+      return true;
     for (unsigned i = 0, e = getNumTypeObjects(); i != e; ++i)
-      if (getTypeObject(i).getAttrs())
+      if (!getTypeObject(i).getAttrs().empty())
         return true;
     return false;
   }
 
   /// Return a source range list of C++11 attributes associated
   /// with the declarator.
   void getCXX11AttributeRanges(SmallVectorImpl<SourceRange> &Ranges) {
-    AttributeList *AttrList = Attrs.getList();
-    while (AttrList) {
-      if (AttrList->isCXX11Attribute())
-        Ranges.push_back(AttrList->getRange());
-      AttrList = AttrList->getNext();
-    }
+    for (const AttributeList &AL : Attrs)
+      if (AL.isCXX11Attribute())
+        Ranges.push_back(AL.getRange());
   }
 
   void setAsmLabel(Expr *E) { AsmLabel = E; }
   Expr *getAsmLabel() const { return AsmLabel; }
 
   void setExtension(bool Val = true) { Extension = Val; }
   bool getExtension() const { return Extension; }
 

include/clang/Sema/Sema.h

DiagnoseSizeOfParametersAndReturnValue(ArrayRef<ParmVarDecl *> Parameters,
                                          QualType ReturnTy, NamedDecl *D);
 
   void DiagnoseInvalidJumps(Stmt *Body);
   Decl *ActOnFileScopeAsmDecl(Expr *expr,
                               SourceLocation AsmLoc,
                               SourceLocation RParenLoc);
 
   /// Handle a C++11 empty-declaration and attribute-declaration.
-  Decl *ActOnEmptyDeclaration(Scope *S,
-                              AttributeList *AttrList,
+  Decl *ActOnEmptyDeclaration(Scope *S, const ParsedAttributesView &AttrList,
                               SourceLocation SemiLoc);
 
   enum class ModuleDeclKind {
     Interface,      ///< 'export module X;'
     Implementation, ///< 'module X;'
     Partition,      ///< 'module partition X;'
   };
 
enum TagUseKind {
     TUK_Reference,   // Reference to a tag:  'struct foo *X;'
     TUK_Declaration, // Fwd decl of a tag:   'struct foo;'
     TUK_Definition,  // Definition of a tag: 'struct foo { int X; } Y;'
     TUK_Friend       // Friend declaration:  'friend struct foo;'
   };
 
   Decl *ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                  SourceLocation KWLoc, CXXScopeSpec &SS, IdentifierInfo *Name,
-                 SourceLocation NameLoc, AttributeList *Attr,
+                 SourceLocation NameLoc, const ParsedAttributesView &Attr,
                  AccessSpecifier AS, SourceLocation ModulePrivateLoc,
                  MultiTemplateParamsArg TemplateParameterLists, bool &OwnedDecl,
                  bool &IsDependent, SourceLocation ScopedEnumKWLoc,
                  bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                  bool IsTypeSpecifier, bool IsTemplateParamOrArg,
                  SkipBodyInfo *SkipBody = nullptr);
 
   Decl *ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                 unsigned TagSpec, SourceLocation TagLoc,
-                                CXXScopeSpec &SS,
-                                IdentifierInfo *Name, SourceLocation NameLoc,
-                                AttributeList *Attr,
+                                CXXScopeSpec &SS, IdentifierInfo *Name,
+                                SourceLocation NameLoc,
+                                const ParsedAttributesView &Attr,
                                 MultiTemplateParamsArg TempParamLists);
 
   TypeResult ActOnDependentTag(Scope *S,
                                unsigned TagSpec,
                                TagUseKind TUK,
                                const CXXScopeSpec &SS,
                                IdentifierInfo *Name,
                                SourceLocation TagLoc,
                                SourceLocation NameLoc);
 
   void ActOnDefs(Scope *S, Decl *TagD, SourceLocation DeclStart,
                  IdentifierInfo *ClassName,
                  SmallVectorImpl<Decl *> &Decls);
   Decl *ActOnField(Scope *S, Decl *TagD, SourceLocation DeclStart,
                    Declarator &D, Expr *BitfieldWidth);
 
   FieldDecl *HandleField(Scope *S, RecordDecl *TagD, SourceLocation DeclStart,
                          Declarator &D, Expr *BitfieldWidth,
                          InClassInitStyle InitStyle,
                          AccessSpecifier AS);
   MSPropertyDecl *HandleMSProperty(Scope *S, RecordDecl *TagD,
-                                   SourceLocation DeclStart,
-                                   Declarator &D, Expr *BitfieldWidth,
+                                   SourceLocation DeclStart, Declarator &D,
+                                   Expr *BitfieldWidth,
                                    InClassInitStyle InitStyle,
                                    AccessSpecifier AS,
-                                   AttributeList *MSPropertyAttr);
+                                   const AttributeList &MSPropertyAttr);
 
   FieldDecl *CheckFieldDecl(DeclarationName Name, QualType T,
                             TypeSourceInfo *TInfo,
                             RecordDecl *Record, SourceLocation Loc,
                             bool Mutable, Expr *BitfieldWidth,
                             InClassInitStyle InitStyle,
                             SourceLocation TSSL,
                             AccessSpecifier AS, NamedDecl *PrevDecl,
public:
   CXXSpecialMember getSpecialMember(const CXXMethodDecl *MD);
   void ActOnLastBitfield(SourceLocation DeclStart,
                          SmallVectorImpl<Decl *> &AllIvarDecls);
   Decl *ActOnIvar(Scope *S, SourceLocation DeclStart,
                   Declarator &D, Expr *BitfieldWidth,
                   tok::ObjCKeywordKind visibility);
 
   // This is used for both record definitions and ObjC interface declarations.
-  void ActOnFields(Scope* S, SourceLocation RecLoc, Decl *TagDecl,
-                   ArrayRef<Decl *> Fields,
-                   SourceLocation LBrac, SourceLocation RBrac,
-                   AttributeList *AttrList);
+  void ActOnFields(Scope *S, SourceLocation RecLoc, Decl *TagDecl,
+                   ArrayRef<Decl *> Fields, SourceLocation LBrac,
+                   SourceLocation RBrac, const ParsedAttributesView &AttrList);
 
   /// ActOnTagStartDefinition - Invoked when we have entered the
   /// scope of a tag's definition (e.g., for an enumeration, class,
   /// struct, or union).
   void ActOnTagStartDefinition(Scope *S, Decl *TagDecl);
 
   /// Perform ODR-like check for C/ObjC when merging tag types from modules.
   /// Differently from C++, actually parse the body and reject / error out
public:
 
   /// Determine whether the body of an anonymous enumeration should be skipped.
   /// \param II The name of the first enumerator.
   SkipBodyInfo shouldSkipAnonEnumBody(Scope *S, IdentifierInfo *II,
                                       SourceLocation IILoc);
 
   Decl *ActOnEnumConstant(Scope *S, Decl *EnumDecl, Decl *LastEnumConstant,
                           SourceLocation IdLoc, IdentifierInfo *Id,
-                          AttributeList *Attrs, SourceLocation EqualLoc,
-                          Expr *Val);
+                          const ParsedAttributesView &Attrs,
+                          SourceLocation EqualLoc, Expr *Val);
   void ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
-                     Decl *EnumDecl,
-                     ArrayRef<Decl *> Elements,
-                     Scope *S, AttributeList *Attr);
+                     Decl *EnumDecl, ArrayRef<Decl *> Elements, Scope *S,
+                     const ParsedAttributesView &Attr);
 
   DeclContext *getContainingDC(DeclContext *DC);
 
   /// Set the current declaration context until it gets popped.
   void PushDeclContext(Scope *S, DeclContext *DC);
   void PopDeclContext();
 
   /// EnterDeclaratorContext - Used when we must lookup names in the context
public:
   void AddKnownFunctionAttributes(FunctionDecl *FD);
 
   // More parsing and symbol table subroutines.
 
   void ProcessPragmaWeak(Scope *S, Decl *D);
   // Decl attributes - this routine is the top level dispatcher.
   void ProcessDeclAttributes(Scope *S, Decl *D, const Declarator &PD);
   // Helper for delayed processing of attributes.
-  void ProcessDeclAttributeDelayed(Decl *D, const AttributeList *AttrList);
-  void ProcessDeclAttributeList(Scope *S, Decl *D, const AttributeList *AL,
+  void ProcessDeclAttributeDelayed(Decl *D,
+                                   const ParsedAttributesView &AttrList);
+  void ProcessDeclAttributeList(Scope *S, Decl *D,
+                                const ParsedAttributesView &AL,
                                 bool IncludeCXX11Attributes = true);
   bool ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,
-                                      const AttributeList *AttrList);
+                                      const ParsedAttributesView &AttrList);
 
   void checkUnusedDeclAttributes(Declarator &D);
 
   /// Determine if type T is a valid subject for a nonnull and similar
   /// attributes. By default, we look through references (the behavior used by
   /// nonnull), but if the second parameter is true, then we treat a reference
   /// type as valid.
   bool isValidPointerAttrType(QualType T, bool RefOkay = false);
public:
   ///
   /// \returns true if nullability cannot be applied, false otherwise.
   bool checkNullabilityTypeSpecifier(QualType &type, NullabilityKind nullability,
                                      SourceLocation nullabilityLoc,
                                      bool isContextSensitive,
                                      bool allowArrayTypes);
 
   /// Stmt attributes - this routine is the top level dispatcher.
-  StmtResult ProcessStmtAttributes(Stmt *Stmt, AttributeList *Attrs,
+  StmtResult ProcessStmtAttributes(Stmt *Stmt,
+                                   const ParsedAttributesView &Attrs,
                                    SourceRange Range);
 
   void WarnConflictingTypedMethods(ObjCMethodDecl *Method,
                                    ObjCMethodDecl *MethodDecl,
                                    bool IsProtocolMethodDecl);
 
   void CheckConflictingOverridingMethod(ObjCMethodDecl *Method,
                                    ObjCMethodDecl *Overridden,
ExprResult ActOnAsTypeExpr(Expr *E, ParsedType ParsedDestTy,
                              SourceLocation BuiltinLoc,
                              SourceLocation RParenLoc);
 
   //===---------------------------- C++ Features --------------------------===//
 
   // Act on C++ namespaces
   Decl *ActOnStartNamespaceDef(Scope *S, SourceLocation InlineLoc,
                                SourceLocation NamespaceLoc,
-                               SourceLocation IdentLoc,
-                               IdentifierInfo *Ident,
+                               SourceLocation IdentLoc, IdentifierInfo *Ident,
                                SourceLocation LBrace,
-                               AttributeList *AttrList,
-                               UsingDirectiveDecl * &UsingDecl);
+                               const ParsedAttributesView &AttrList,
+                               UsingDirectiveDecl *&UsingDecl);
   void ActOnFinishNamespaceDef(Decl *Dcl, SourceLocation RBrace);
 
   NamespaceDecl *getStdNamespace() const;
   NamespaceDecl *getOrCreateStdNamespace();
 
   NamespaceDecl *lookupStdExperimentalNamespace();
 
   CXXRecordDecl *getStdBadAlloc() const;
public:
   ///
   /// \returns The instantiated template, or null on error.
   QualType BuildStdInitializerList(QualType Element, SourceLocation Loc);
 
   /// Determine whether Ctor is an initializer-list constructor, as
   /// defined in [dcl.init.list]p2.
   bool isInitListConstructor(const FunctionDecl *Ctor);
 
-  Decl *ActOnUsingDirective(Scope *CurScope,
-                            SourceLocation UsingLoc,
-                            SourceLocation NamespcLoc,
-                            CXXScopeSpec &SS,
+  Decl *ActOnUsingDirective(Scope *CurScope, SourceLocation UsingLoc,
+                            SourceLocation NamespcLoc, CXXScopeSpec &SS,
                             SourceLocation IdentLoc,
                             IdentifierInfo *NamespcName,
-                            AttributeList *AttrList);
+                            const ParsedAttributesView &AttrList);
 
   void PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir);
 
   Decl *ActOnNamespaceAliasDef(Scope *CurScope,
                                SourceLocation NamespaceLoc,
                                SourceLocation AliasLoc,
                                IdentifierInfo *Alias,
                                CXXScopeSpec &SS,
bool CheckUsingDeclRedeclaration(SourceLocation UsingLoc,
                                    SourceLocation NameLoc,
                                    const LookupResult &Previous);
   bool CheckUsingDeclQualifier(SourceLocation UsingLoc,
                                bool HasTypename,
                                const CXXScopeSpec &SS,
                                const DeclarationNameInfo &NameInfo,
                                SourceLocation NameLoc);
 
-  NamedDecl *BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
-                                   SourceLocation UsingLoc,
-                                   bool HasTypenameKeyword,
-                                   SourceLocation TypenameLoc,
-                                   CXXScopeSpec &SS,
-                                   DeclarationNameInfo NameInfo,
-                                   SourceLocation EllipsisLoc,
-                                   AttributeList *AttrList,
-                                   bool IsInstantiation);
+  NamedDecl *BuildUsingDeclaration(
+      Scope *S, AccessSpecifier AS, SourceLocation UsingLoc,
+      bool HasTypenameKeyword, SourceLocation TypenameLoc, CXXScopeSpec &SS,
+      DeclarationNameInfo NameInfo, SourceLocation EllipsisLoc,
+      const ParsedAttributesView &AttrList, bool IsInstantiation);
   NamedDecl *BuildUsingPackDecl(NamedDecl *InstantiatedFrom,
                                 ArrayRef<NamedDecl *> Expansions);
 
   bool CheckInheritingConstructorUsingDecl(UsingDecl *UD);
 
   /// Given a derived-class using shadow declaration for a constructor and the
   /// correspnding base class constructor, find or create the implicit
   /// synthesized derived class constructor to use for this initialization.
   CXXConstructorDecl *
   findInheritingConstructor(SourceLocation Loc, CXXConstructorDecl *BaseCtor,
                             ConstructorUsingShadowDecl *DerivedShadow);
 
-  Decl *ActOnUsingDeclaration(Scope *CurScope,
-                              AccessSpecifier AS,
+  Decl *ActOnUsingDeclaration(Scope *CurScope, AccessSpecifier AS,
                               SourceLocation UsingLoc,
-                              SourceLocation TypenameLoc,
-                              CXXScopeSpec &SS,
-                              UnqualifiedId &Name,
-                              SourceLocation EllipsisLoc,
-                              AttributeList *AttrList);
-  Decl *ActOnAliasDeclaration(Scope *CurScope,
-                              AccessSpecifier AS,
+                              SourceLocation TypenameLoc, CXXScopeSpec &SS,
+                              UnqualifiedId &Name, SourceLocation EllipsisLoc,
+                              const ParsedAttributesView &AttrList);
+  Decl *ActOnAliasDeclaration(Scope *CurScope, AccessSpecifier AS,
                               MultiTemplateParamsArg TemplateParams,
-                              SourceLocation UsingLoc,
-                              UnqualifiedId &Name,
-                              AttributeList *AttrList,
-                              TypeResult Type,
-                              Decl *DeclFromDeclSpec);
+                              SourceLocation UsingLoc, UnqualifiedId &Name,
+                              const ParsedAttributesView &AttrList,
+                              TypeResult Type, Decl *DeclFromDeclSpec);
 
   /// BuildCXXConstructExpr - Creates a complete call to a constructor,
   /// including handling of its default argument expressions.
   ///
   /// \param ConstructKind - a CXXConstructExpr::ConstructionKind
   ExprResult
   BuildCXXConstructExpr(SourceLocation ConstructLoc, QualType DeclInitType,
                         NamedDecl *FoundDecl,

   //===--------------------------------------------------------------------===//
   // C++ Classes
   //
   CXXRecordDecl *getCurrentClass(Scope *S, const CXXScopeSpec *SS);
   bool isCurrentClassName(const IdentifierInfo &II, Scope *S,
                           const CXXScopeSpec *SS = nullptr);
   bool isCurrentClassNameTypo(IdentifierInfo *&II, const CXXScopeSpec *SS);
 
-  bool ActOnAccessSpecifier(AccessSpecifier Access,
-                            SourceLocation ASLoc,
+  bool ActOnAccessSpecifier(AccessSpecifier Access, SourceLocation ASLoc,
                             SourceLocation ColonLoc,
-                            AttributeList *Attrs = nullptr);
+                            const ParsedAttributesView &Attrs);
 
   NamedDecl *ActOnCXXMemberDeclarator(Scope *S, AccessSpecifier AS,
                                  Declarator &D,
                                  MultiTemplateParamsArg TemplateParameterLists,
                                  Expr *BitfieldWidth, const VirtSpecifiers &VS,
                                  InClassInitStyle InitStyle);
 
   void ActOnStartCXXInClassMemberInitializer();
void propagateDLLAttrToBaseClassTemplate(
       SourceLocation BaseLoc);
 
   void CheckCompletedCXXClass(CXXRecordDecl *Record);
 
   /// Check that the C++ class annoated with "trivial_abi" satisfies all the
   /// conditions that are needed for the attribute to have an effect.
   void checkIllFormedTrivialABIStruct(CXXRecordDecl &RD);
 
-  void ActOnFinishCXXMemberSpecification(Scope* S, SourceLocation RLoc,
-                                         Decl *TagDecl,
-                                         SourceLocation LBrac,
+  void ActOnFinishCXXMemberSpecification(Scope *S, SourceLocation RLoc,
+                                         Decl *TagDecl, SourceLocation LBrac,
                                          SourceLocation RBrac,
-                                         AttributeList *AttrList);
+                                         const ParsedAttributesView &AttrList);
   void ActOnFinishCXXMemberDecls();
   void ActOnFinishCXXNonNestedClass(Decl *D);
 
   void ActOnReenterCXXMethodParameter(Scope *S, ParmVarDecl *Param);
   unsigned ActOnReenterTemplateScope(Scope *S, Decl *Template);
   void ActOnStartDelayedMemberDeclarations(Scope *S, Decl *Record);
   void ActOnStartDelayedCXXMethodDeclaration(Scope *S, Decl *Method);
   void ActOnDelayedCXXMethodParameter(Scope *S, Decl *Param);
bool CheckTemplateParameterList(TemplateParameterList *NewParams,
                                   TemplateParameterList *OldParams,
                                   TemplateParamListContext TPC);
   TemplateParameterList *MatchTemplateParametersToScopeSpecifier(
       SourceLocation DeclStartLoc, SourceLocation DeclLoc,
       const CXXScopeSpec &SS, TemplateIdAnnotation *TemplateId,
       ArrayRef<TemplateParameterList *> ParamLists,
       bool IsFriend, bool &IsMemberSpecialization, bool &Invalid);
 
-  DeclResult CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
-                                SourceLocation KWLoc, CXXScopeSpec &SS,
-                                IdentifierInfo *Name, SourceLocation NameLoc,
-                                AttributeList *Attr,
-                                TemplateParameterList *TemplateParams,
-                                AccessSpecifier AS,
-                                SourceLocation ModulePrivateLoc,
-                                SourceLocation FriendLoc,
-                                unsigned NumOuterTemplateParamLists,
-                            TemplateParameterList **OuterTemplateParamLists,
-                                SkipBodyInfo *SkipBody = nullptr);
+  DeclResult CheckClassTemplate(
+      Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
+      CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
+      const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
+      AccessSpecifier AS, SourceLocation ModulePrivateLoc,
+      SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
 
   TemplateArgumentLoc getTrivialTemplateArgumentLoc(const TemplateArgument &Arg,
                                                     QualType NTTPType,
                                                     SourceLocation Loc);
 
   void translateTemplateArguments(const ASTTemplateArgsPtr &In,
                                   TemplateArgumentListInfo &Out);
 
ExprResult BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
                                const DeclarationNameInfo &NameInfo,
                                const TemplateArgumentListInfo *TemplateArgs);
 
   TemplateNameKind ActOnDependentTemplateName(
       Scope *S, CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
       const UnqualifiedId &Name, ParsedType ObjectType, bool EnteringContext,
       TemplateTy &Template, bool AllowInjectedClassName = false);
 
-  DeclResult
-  ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec, TagUseKind TUK,
-                                   SourceLocation KWLoc,
-                                   SourceLocation ModulePrivateLoc,
-                                   TemplateIdAnnotation &TemplateId,
-                                   AttributeList *Attr,
-                                 MultiTemplateParamsArg TemplateParameterLists,
-                                   SkipBodyInfo *SkipBody = nullptr);
+  DeclResult ActOnClassTemplateSpecialization(
+      Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
+      SourceLocation ModulePrivateLoc, TemplateIdAnnotation &TemplateId,
+      const ParsedAttributesView &Attr,
 
   bool CheckTemplatePartialSpecializationArgs(SourceLocation Loc,
                                               TemplateDecl *PrimaryTemplate,
                                               unsigned NumExplicitArgs,
                                               ArrayRef<TemplateArgument> Args);
   void CheckTemplatePartialSpecialization(
       ClassTemplatePartialSpecializationDecl *Partial);
   void CheckTemplatePartialSpecialization(
bool CheckDependentFunctionTemplateSpecialization(FunctionDecl *FD,
                                                     LookupResult &Previous);
 
   bool CheckFunctionTemplateSpecialization(FunctionDecl *FD,
                          TemplateArgumentListInfo *ExplicitTemplateArgs,
                                            LookupResult &Previous);
   bool CheckMemberSpecialization(NamedDecl *Member, LookupResult &Previous);
   void CompleteMemberSpecialization(NamedDecl *Member, LookupResult &Previous);
 
-  DeclResult
-  ActOnExplicitInstantiation(Scope *S,
-                             SourceLocation ExternLoc,
-                             SourceLocation TemplateLoc,
-                             unsigned TagSpec,
-                             SourceLocation KWLoc,
-                             const CXXScopeSpec &SS,
-                             TemplateTy Template,
-                             SourceLocation TemplateNameLoc,
-                             SourceLocation LAngleLoc,
-                             ASTTemplateArgsPtr TemplateArgs,
-                             SourceLocation RAngleLoc,
-                             AttributeList *Attr);
+  DeclResult ActOnExplicitInstantiation(
+      Scope *S, SourceLocation ExternLoc, SourceLocation TemplateLoc,
+      unsigned TagSpec, SourceLocation KWLoc, const CXXScopeSpec &SS,
+      TemplateTy Template, SourceLocation TemplateNameLoc,
+      SourceLocation LAngleLoc, ASTTemplateArgsPtr TemplateArgs,
+      SourceLocation RAngleLoc, const ParsedAttributesView &Attr);
 
-  DeclResult
-  ActOnExplicitInstantiation(Scope *S,
-                             SourceLocation ExternLoc,
+  DeclResult ActOnExplicitInstantiation(Scope *S, SourceLocation ExternLoc,
                                         SourceLocation TemplateLoc,
-                             unsigned TagSpec,
-                             SourceLocation KWLoc,
-                             CXXScopeSpec &SS,
-                             IdentifierInfo *Name,
+                                        unsigned TagSpec, SourceLocation KWLoc,
+                                        CXXScopeSpec &SS, IdentifierInfo *Name,
                                         SourceLocation NameLoc,
-                             AttributeList *Attr);
+                                        const ParsedAttributesView &Attr);
 
   DeclResult ActOnExplicitInstantiation(Scope *S,
                                         SourceLocation ExternLoc,
                                         SourceLocation TemplateLoc,
                                         Declarator &D);
 
   TemplateArgumentLoc
   SubstDefaultTemplateArgumentIfAvailable(TemplateDecl *Template,
DeclResult actOnObjCTypeParam(Scope *S,
                                 SourceLocation colonLoc,
                                 ParsedType typeBound);
 
   ObjCTypeParamList *actOnObjCTypeParamList(Scope *S, SourceLocation lAngleLoc,
                                             ArrayRef<Decl *> typeParams,
                                             SourceLocation rAngleLoc);
   void popObjCTypeParamList(Scope *S, ObjCTypeParamList *typeParamList);
 
-  Decl *ActOnStartClassInterface(Scope *S,
-                                 SourceLocation AtInterfaceLoc,
-                                 IdentifierInfo *ClassName,
-                                 SourceLocation ClassLoc,
-                                 ObjCTypeParamList *typeParamList,
-                                 IdentifierInfo *SuperName,
-                                 SourceLocation SuperLoc,
-                                 ArrayRef<ParsedType> SuperTypeArgs,
-                                 SourceRange SuperTypeArgsRange,
-                                 Decl * const *ProtoRefs,
-                                 unsigned NumProtoRefs,
-                                 const SourceLocation *ProtoLocs,
-                                 SourceLocation EndProtoLoc,
-                                 AttributeList *AttrList);
+  Decl *ActOnStartClassInterface(
+      Scope *S, SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
+      SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
+      IdentifierInfo *SuperName, SourceLocation SuperLoc,
+      ArrayRef<ParsedType> SuperTypeArgs, SourceRange SuperTypeArgsRange,
+      Decl *const *ProtoRefs, unsigned NumProtoRefs,
+      const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
+      const ParsedAttributesView &AttrList);
 
   void ActOnSuperClassOfClassInterface(Scope *S,
                                        SourceLocation AtInterfaceLoc,
                                        ObjCInterfaceDecl *IDecl,
                                        IdentifierInfo *ClassName,
                                        SourceLocation ClassLoc,
                                        IdentifierInfo *SuperName,
                                        SourceLocation SuperLoc,
Decl *ActOnCompatibilityAlias(
                     IdentifierInfo *ClassName, SourceLocation ClassLocation);
 
   bool CheckForwardProtocolDeclarationForCircularDependency(
     IdentifierInfo *PName,
     SourceLocation &PLoc, SourceLocation PrevLoc,
     const ObjCList<ObjCProtocolDecl> &PList);
 
   Decl *ActOnStartProtocolInterface(
-                    SourceLocation AtProtoInterfaceLoc,
-                    IdentifierInfo *ProtocolName, SourceLocation ProtocolLoc,
-                    Decl * const *ProtoRefNames, unsigned NumProtoRefs,
-                    const SourceLocation *ProtoLocs,
-                    SourceLocation EndProtoLoc,
-                    AttributeList *AttrList);
-
-  Decl *ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
-                                    IdentifierInfo *ClassName,
-                                    SourceLocation ClassLoc,
-                                    ObjCTypeParamList *typeParamList,
-                                    IdentifierInfo *CategoryName,
-                                    SourceLocation CategoryLoc,
-                                    Decl * const *ProtoRefs,
-                                    unsigned NumProtoRefs,
-                                    const SourceLocation *ProtoLocs,
-                                    SourceLocation EndProtoLoc,
-                                    AttributeList *AttrList);
+      SourceLocation AtProtoInterfaceLoc, IdentifierInfo *ProtocolName,
+      SourceLocation ProtocolLoc, Decl *const *ProtoRefNames,
+      unsigned NumProtoRefs, const SourceLocation *ProtoLocs,
+      SourceLocation EndProtoLoc, const ParsedAttributesView &AttrList);
+
+  Decl *ActOnStartCategoryInterface(
+      SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
+      SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
+      IdentifierInfo *CategoryName, SourceLocation CategoryLoc,
+      Decl *const *ProtoRefs, unsigned NumProtoRefs,
+      const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
+      const ParsedAttributesView &AttrList);
 
   Decl *ActOnStartClassImplementation(
                     SourceLocation AtClassImplLoc,
                     IdentifierInfo *ClassName, SourceLocation ClassLoc,
                     IdentifierInfo *SuperClassname,
                     SourceLocation SuperClassLoc);
 
   Decl *ActOnStartCategoryImplementation(SourceLocation AtCatImplLoc,
                                          IdentifierInfo *ClassName,
                                          SourceLocation ClassLoc,
                                          IdentifierInfo *CatName,
                                          SourceLocation CatLoc);
 
   DeclGroupPtrTy ActOnFinishObjCImplementation(Decl *ObjCImpDecl,
                                                ArrayRef<Decl *> Decls);
 
   DeclGroupPtrTy ActOnForwardClassDeclaration(SourceLocation Loc,
                    IdentifierInfo **IdentList,
                    SourceLocation *IdentLocs,
                    ArrayRef<ObjCTypeParamList *> TypeParamLists,
                    unsigned NumElts);
 
-  DeclGroupPtrTy ActOnForwardProtocolDeclaration(SourceLocation AtProtoclLoc,
-                                        ArrayRef<IdentifierLocPair> IdentList,
-                                        AttributeList *attrList);
+  DeclGroupPtrTy
+  ActOnForwardProtocolDeclaration(SourceLocation AtProtoclLoc,
+                                  const ParsedAttributesView &attrList);
 
   void FindProtocolDeclaration(bool WarnOnDeclarations, bool ForObjCContainer,
                                ArrayRef<IdentifierLocPair> ProtocolId,
                                SmallVectorImpl<Decl *> &Protocols);
 
   void DiagnoseTypeArgsAndProtocols(IdentifierInfo *ProtocolId,
                                     SourceLocation ProtocolLoc,
                                     IdentifierInfo *TypeArgId,
struct ObjCArgInfo {
     IdentifierInfo *Name;
     SourceLocation NameLoc;
     // The Type is null if no type was specified, and the DeclSpec is invalid
     // in this case.
     ParsedType Type;
     ObjCDeclSpec DeclSpec;
 
     /// ArgAttrs - Attribute list for this argument.
-    AttributeList *ArgAttrs;
+    ParsedAttributesView ArgAttrs;
   };
 
   Decl *ActOnMethodDeclaration(
       Scope *S,
       SourceLocation BeginLoc, // location of the + or -.
       SourceLocation EndLoc,   // location of the ; or {.
-    tok::TokenKind MethodType,
-    ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
+      tok::TokenKind MethodType, ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
       ArrayRef<SourceLocation> SelectorLocs, Selector Sel,
       // optional arguments. The number of types/arguments is obtained
       // from the Sel.getNumArgs().
-    ObjCArgInfo *ArgInfo,
-    DeclaratorChunk::ParamInfo *CParamInfo, unsigned CNumArgs, // c-style args
-    AttributeList *AttrList, tok::ObjCKeywordKind MethodImplKind,
+      ObjCArgInfo *ArgInfo, DeclaratorChunk::ParamInfo *CParamInfo,
+      unsigned CNumArgs, // c-style args
+      const ParsedAttributesView &AttrList, tok::ObjCKeywordKind MethodImplKind,
       bool isVariadic, bool MethodDefinition);
 
   ObjCMethodDecl *LookupMethodInQualifiedType(Selector Sel,
                                               const ObjCObjectPointerType *OPT,
                                               bool IsInstance);
   ObjCMethodDecl *LookupMethodInObjectType(Selector Sel, QualType Ty,
                                            bool IsInstance);
 
   bool CheckARCMethodDecl(ObjCMethodDecl *method);
public:
 
   /// Determines whether the given function is a CUDA device/host/kernel/etc.
   /// function.
   ///
   /// Use this rather than examining the function's attributes yourself -- you
   /// will get it wrong.  Returns CFT_Host if D is null.
   CUDAFunctionTarget IdentifyCUDATarget(const FunctionDecl *D,
                                         bool IgnoreImplicitHDAttr = false);
-  CUDAFunctionTarget IdentifyCUDATarget(const AttributeList *Attr);
+  CUDAFunctionTarget IdentifyCUDATarget(const ParsedAttributesView &Attrs);
 
   /// Gets the CUDA target for the current context.
   CUDAFunctionTarget CurrentCUDATarget() {
     return IdentifyCUDATarget(dyn_cast<FunctionDecl>(CurContext));
   }
 
   // CUDA function call preference. Must be ordered numerically from
   // worst to best.

lib/Parse/ParseCXXInlineMethods.cpp

 #include "clang/Parse/RAIIObjectsForParser.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/Scope.h"
 using namespace clang;
 
 /// ParseCXXInlineMethodDef - We parsed and verified that the specified
 /// Declarator is a well formed C++ inline method definition. Now lex its body
 /// and store its tokens for parsing after the C++ class is complete.
-NamedDecl *Parser::ParseCXXInlineMethodDef(AccessSpecifier AS,
-                                      AttributeList *AccessAttrs,
-                                      ParsingDeclarator &D,
-                                      const ParsedTemplateInfo &TemplateInfo,
-                                      const VirtSpecifiers& VS,
-                                      SourceLocation PureSpecLoc) {
+NamedDecl *Parser::ParseCXXInlineMethodDef(
+    AccessSpecifier AS, ParsedAttributes &AccessAttrs, ParsingDeclarator &D,
+    const ParsedTemplateInfo &TemplateInfo, const VirtSpecifiers &VS,
   assert(D.isFunctionDeclarator() && "This isn't a function declarator!");
   assert(Tok.isOneOf(tok::l_brace, tok::colon, tok::kw_try, tok::equal) &&
          "Current token not a '{', ':', '=', or 'try'!");
 
   MultiTemplateParamsArg TemplateParams(
       TemplateInfo.TemplateParams ? TemplateInfo.TemplateParams->data()
                                   : nullptr,
       TemplateInfo.TemplateParams ? TemplateInfo.TemplateParams->size() : 0);
 
   NamedDecl *FnD;
   if (D.getDeclSpec().isFriendSpecified())
     FnD = Actions.ActOnFriendFunctionDecl(getCurScope(), D,
                                           TemplateParams);
   else {
     FnD = Actions.ActOnCXXMemberDeclarator(getCurScope(), AS, D,
                                            TemplateParams, nullptr,
                                            VS, ICIS_NoInit);
     if (FnD) {
       Actions.ProcessDeclAttributeList(getCurScope(), FnD, AccessAttrs);
       if (PureSpecLoc.isValid())
         Actions.ActOnPureSpecifier(FnD, PureSpecLoc);
     }
   }
 
   if (FnD)
     HandleMemberFunctionDeclDelays(D, FnD);
 
   D.complete(FnD);

lib/Parse/ParseDecl.cpp

TypeResult Parser::ParseTypeName(SourceRange *Range,
                                  ParsedAttributes *Attrs) {
   DeclSpecContext DSC = getDeclSpecContextFromDeclaratorContext(Context);
   if (DSC == DeclSpecContext::DSC_normal)
     DSC = DeclSpecContext::DSC_type_specifier;
 
   // Parse the common declaration-specifiers piece.
   DeclSpec DS(AttrFactory);
   if (Attrs)
-    DS.addAttributes(Attrs->getList());
+    DS.addAttributes(*Attrs);
   ParseSpecifierQualifierList(DS, AS, DSC);
   if (OwnedType)
     *OwnedType = DS.isTypeSpecOwned() ? DS.getRepAsDecl() : nullptr;
 
   // Parse the abstract-declarator, if present.
   Declarator DeclaratorInfo(DS, Context);
   ParseDeclarator(DeclaratorInfo);
   if (Range)
case AttributeList::AT_ObjCBridgeRelated:
     ParseObjCBridgeRelatedAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                     ScopeName, ScopeLoc, Syntax);
     break;
   case AttributeList::AT_TypeTagForDatatype:
     ParseTypeTagForDatatypeAttribute(*AttrName, AttrNameLoc, Attrs, EndLoc,
                                      ScopeName, ScopeLoc, Syntax);
     break;
   }
-  return Attrs.getList() ? Attrs.getList()->getNumArgs() : 0;
+  return !Attrs.empty() ? Attrs.begin()->getNumArgs() : 0;
 }
 
 bool Parser::ParseMicrosoftDeclSpecArgs(IdentifierInfo *AttrName,
                                         SourceLocation AttrNameLoc,
                                         ParsedAttributes &Attrs) {
   // If the attribute isn't known, we will not attempt to parse any
   // arguments.
   if (!hasAttribute(AttrSyntax::Declspec, nullptr, AttrName,
bool Parser::ParseMicrosoftDeclSpecArgs(IdentifierInfo *AttrName,
   }
 
   unsigned NumArgs =
       ParseAttributeArgsCommon(AttrName, AttrNameLoc, Attrs, nullptr, nullptr,
                                SourceLocation(), AttributeList::AS_Declspec);
 
   // If this attribute's args were parsed, and it was expected to have
   // arguments but none were provided, emit a diagnostic.
-  const AttributeList *Attr = Attrs.getList();
-  if (Attr && Attr->getMaxArgs() && !NumArgs) {
+  if (!Attrs.empty() && Attrs.begin()->getMaxArgs() && !NumArgs) {
     Diag(OpenParenLoc, diag::err_attribute_requires_arguments) << AttrName;
     return false;
   }
   return true;
 }
 
 /// [MS] decl-specifier:
 ///             __declspec ( extended-decl-modifier-seq )
if (LA.Decls.size() == 1) {
       ParseGNUAttributeArgs(&LA.AttrName, LA.AttrNameLoc, Attrs, &endLoc,
                             nullptr, SourceLocation(), AttributeList::AS_GNU,
                             nullptr);
     }
   } else {
     Diag(Tok, diag::warn_attribute_no_decl) << LA.AttrName.getName();
   }
 
-  const AttributeList *AL = Attrs.getList();
-  if (OnDefinition && AL && !AL->isCXX11Attribute() &&
-      AL->isKnownToGCC())
+  if (OnDefinition && !Attrs.empty() && !Attrs.begin()->isCXX11Attribute() &&
+      Attrs.begin()->isKnownToGCC())
     Diag(Tok, diag::warn_attribute_on_function_definition)
       << &LA.AttrName;
 
   for (unsigned i = 0, ni = LA.Decls.size(); i < ni; ++i)
     Actions.ActOnFinishDelayedAttribute(getCurScope(), LA.Decls[i], Attrs);
 
   // Due to a parsing error, we either went over the cached tokens or
   // there are still cached tokens left, so we skip the leftover tokens.
void Parser::DiagnoseMisplacedCXX11Attribute(ParsedAttributesWithRange &Attrs,
   ParseCXX11Attributes(Attrs);
   CharSourceRange AttrRange(SourceRange(Loc, Attrs.Range.getEnd()), true);
   // FIXME: use err_attributes_misplaced
   Diag(Loc, diag::err_attributes_not_allowed)
     << FixItHint::CreateInsertionFromRange(CorrectLocation, AttrRange)
     << FixItHint::CreateRemoval(AttrRange);
 }
 
-void Parser::DiagnoseProhibitedAttributes(ParsedAttributesWithRange &attrs,
-                                          const SourceLocation CorrectLocation) {
+void Parser::DiagnoseProhibitedAttributes(
+    const SourceRange &Range, const SourceLocation CorrectLocation) {
   if (CorrectLocation.isValid()) {
-    CharSourceRange AttrRange(attrs.Range, true);
+    CharSourceRange AttrRange(Range, true);
     Diag(CorrectLocation, diag::err_attributes_misplaced)
         << FixItHint::CreateInsertionFromRange(CorrectLocation, AttrRange)
         << FixItHint::CreateRemoval(AttrRange);
   } else
-    Diag(attrs.Range.getBegin(), diag::err_attributes_not_allowed) << attrs.Range;
+    Diag(Range.getBegin(), diag::err_attributes_not_allowed) << Range;
 }
 
 void Parser::ProhibitCXX11Attributes(ParsedAttributesWithRange &Attrs,
                                      unsigned DiagID) {
-  for (AttributeList *Attr = Attrs.getList(); Attr; Attr = Attr->getNext()) {
-    if (!Attr->isCXX11Attribute() && !Attr->isC2xAttribute())
+  for (const AttributeList &AL : Attrs) {
+    if (!AL.isCXX11Attribute() && !AL.isC2xAttribute())
       continue;
-    if (Attr->getKind() == AttributeList::UnknownAttribute)
-      Diag(Attr->getLoc(), diag::warn_unknown_attribute_ignored)
-          << Attr->getName();
+    if (AL.getKind() == AttributeList::UnknownAttribute)
+      Diag(AL.getLoc(), diag::warn_unknown_attribute_ignored) << AL.getName();
     else {
-      Diag(Attr->getLoc(), DiagID)
-        << Attr->getName();
-      Attr->setInvalid();
+      Diag(AL.getLoc(), DiagID) << AL.getName();
+      AL.setInvalid();
     }
   }
 }
 
 // Usually, `__attribute__((attrib)) class Foo {} var` means that attribute
 // applies to var, not the type Foo.
 // As an exception to the rule, __declspec(align(...)) before the
 // class-key affects the type instead of the variable.
 // Also, Microsoft-style [attributes] seem to affect the type instead of the
 // variable.
 // This function moves attributes that should apply to the type off DS to Attrs.
 void Parser::stripTypeAttributesOffDeclSpec(ParsedAttributesWithRange &Attrs,
                                             DeclSpec &DS,
                                             Sema::TagUseKind TUK) {
   if (TUK == Sema::TUK_Reference)
     return;
 
-  ParsedAttributes &PA = DS.getAttributes();
-  AttributeList *AL = PA.getList();
-  AttributeList *Prev = nullptr;
-  AttributeList *TypeAttrHead = nullptr;
-  AttributeList *TypeAttrTail = nullptr;
-  while (AL) {
-    AttributeList *Next = AL->getNext();
-
-    if ((AL->getKind() == AttributeList::AT_Aligned &&
-         AL->isDeclspecAttribute()) ||
-        AL->isMicrosoftAttribute()) {
-      // Stitch the attribute into the tag's attribute list.
-      if (TypeAttrTail)
-        TypeAttrTail->setNext(AL);
-      else
-        TypeAttrHead = AL;
-      TypeAttrTail = AL;
-      TypeAttrTail->setNext(nullptr);
+  llvm::SmallVector<AttributeList *, 1> ToBeMoved;
 
-      // Remove the attribute from the variable's attribute list.
-      if (Prev) {
-        // Set the last variable attribute's next attribute to be the attribute
-        // after the current one.
-        Prev->setNext(Next);
-      } else {
-        // Removing the head of the list requires us to reset the head to the
-        // next attribute.
-        PA.set(Next);
-      }
-    } else {
-      Prev = AL;
-    }
+  for (AttributeList &AL : DS.getAttributes()) {
+    if ((AL.getKind() == AttributeList::AT_Aligned &&
+         AL.isDeclspecAttribute()) ||
+        AL.isMicrosoftAttribute())
+      ToBeMoved.push_back(&AL);
 
-    AL = Next;
+  for (AttributeList *AL : ToBeMoved) {
+    DS.getAttributes().remove(AL);
+    Attrs.addAtEnd(AL);
   }
-
-  // Find end of type attributes Attrs and add NewTypeAttributes in the same
-  // order they were in originally.  (Remember, in AttributeList things earlier
-  // in source order are later in the list, since new attributes are added to
-  // the front of the list.)
-  Attrs.addAllAtEnd(TypeAttrHead);
 }
 
 /// ParseDeclaration - Parse a full 'declaration', which consists of
 /// declaration-specifiers, some number of declarators, and a semicolon.
 /// 'Context' should be a DeclaratorContext value.  This returns the
 /// location of the semicolon in DeclEnd.
 ///
 ///       declaration: [C99 6.7]
Parser::DeclGroupPtrTy Parser::ParseDeclaration(DeclaratorContext Context,
   // parsing c none objective-c decls.
   ObjCDeclContextSwitch ObjCDC(*this);
 
   Decl *SingleDecl = nullptr;
   switch (Tok.getKind()) {
   case tok::kw_template:
   case tok::kw_export:
     ProhibitAttributes(attrs);
-    SingleDecl = ParseDeclarationStartingWithTemplate(Context, DeclEnd);
+    SingleDecl = ParseDeclarationStartingWithTemplate(Context, DeclEnd, attrs);
     break;
   case tok::kw_inline:
     // Could be the start of an inline namespace. Allowed as an ext in C++03.
     if (getLangOpts().CPlusPlus && NextToken().is(tok::kw_namespace)) {
       ProhibitAttributes(attrs);
       SourceLocation InlineLoc = ConsumeToken();
       return ParseNamespace(Context, DeclEnd, InlineLoc);
     }
void Parser::ParseStructUnionBody(SourceLocation RecordLoc,
   }
 
   T.consumeClose();
 
   ParsedAttributes attrs(AttrFactory);
   // If attributes exist after struct contents, parse them.
   MaybeParseGNUAttributes(attrs);
 
-  Actions.ActOnFields(getCurScope(),
-                      RecordLoc, TagDecl, FieldDecls,
-                      T.getOpenLocation(), T.getCloseLocation(),
-                      attrs.getList());
+  Actions.ActOnFields(getCurScope(), RecordLoc, TagDecl, FieldDecls,
+                      T.getOpenLocation(), T.getCloseLocation(), attrs);
   StructScope.Exit();
   Actions.ActOnTagFinishDefinition(getCurScope(), TagDecl, T.getRange());
 }
 
 /// ParseEnumSpecifier
 ///       enum-specifier: [C99 6.7.2.2]
 ///         'enum' identifier[opt] '{' enumerator-list '}'
 ///[C99/C++]'enum' identifier[opt] '{' enumerator-list ',' '}'
SkipBody = Actions.shouldSkipAnonEnumBody(getCurScope(),
                                               NextToken().getLocation());
 
   bool Owned = false;
   bool IsDependent = false;
   const char *PrevSpec = nullptr;
   unsigned DiagID;
   Decl *TagDecl = Actions.ActOnTag(
       getCurScope(), DeclSpec::TST_enum, TUK, StartLoc, SS, Name, NameLoc,
-      attrs.getList(), AS, DS.getModulePrivateSpecLoc(), TParams, Owned,
-      IsDependent, ScopedEnumKWLoc, IsScopedUsingClassTag, BaseType,
+      attrs, AS, DS.getModulePrivateSpecLoc(), TParams, Owned, IsDependent,
+      ScopedEnumKWLoc, IsScopedUsingClassTag, BaseType,
       DSC == DeclSpecContext::DSC_type_specifier,
       DSC == DeclSpecContext::DSC_template_param ||
           DSC == DeclSpecContext::DSC_template_type_arg,
       &SkipBody);
 
   if (SkipBody.ShouldSkip) {
     assert(TUK == Sema::TUK_Definition && "can only skip a definition");
 
while (Tok.isNot(tok::r_brace)) {
     if (TryConsumeToken(tok::equal, EqualLoc)) {
       AssignedVal = ParseConstantExpression();
       if (AssignedVal.isInvalid())
         SkipUntil(tok::comma, tok::r_brace, StopBeforeMatch);
     }
 
     // Install the enumerator constant into EnumDecl.
     Decl *EnumConstDecl = Actions.ActOnEnumConstant(
-        getCurScope(), EnumDecl, LastEnumConstDecl, IdentLoc, Ident,
-        attrs.getList(), EqualLoc, AssignedVal.get());
+        getCurScope(), EnumDecl, LastEnumConstDecl, IdentLoc, Ident, attrs,
+        EqualLoc, AssignedVal.get());
     EnumAvailabilityDiags.back().done();
 
     EnumConstantDecls.push_back(EnumConstDecl);
     LastEnumConstDecl = EnumConstDecl;
 
     if (Tok.is(tok::identifier)) {
       // We're missing a comma between enumerators.
       SourceLocation Loc = getEndOfPreviousToken();
void Parser::ParseEnumBody(SourceLocation StartLoc, Decl *EnumDecl) {
 
   // Eat the }.
   T.consumeClose();
 
   // If attributes exist after the identifier list, parse them.
   ParsedAttributes attrs(AttrFactory);
   MaybeParseGNUAttributes(attrs);
 
-  Actions.ActOnEnumBody(StartLoc, T.getRange(),
-                        EnumDecl, EnumConstantDecls,
-                        getCurScope(),
-                        attrs.getList());
+  Actions.ActOnEnumBody(StartLoc, T.getRange(), EnumDecl, EnumConstantDecls,
+                        getCurScope(), attrs);
 
   // Now handle enum constant availability diagnostics.
   assert(EnumConstantDecls.size() == EnumAvailabilityDiags.size());
   for (size_t i = 0, e = EnumConstantDecls.size(); i != e; ++i) {
     ParsingDeclRAIIObject PD(*this, ParsingDeclRAIIObject::NoParent);
     EnumAvailabilityDiags[i].redelay();
     PD.complete(EnumConstantDecls[i]);
   }
if (SS.isNotEmpty()) {
       ParseTypeQualifierListOpt(DS);
       D.ExtendWithDeclSpec(DS);
 
       // Recurse to parse whatever is left.
       ParseDeclaratorInternal(D, DirectDeclParser);
 
       // Sema will have to catch (syntactically invalid) pointers into global
       // scope. It has to catch pointers into namespace scope anyway.
-      D.AddTypeInfo(DeclaratorChunk::getMemberPointer(SS,DS.getTypeQualifiers(),
-                                                      DS.getLocEnd()),
-                    DS.getAttributes(),
-                    /* Don't replace range end. */SourceLocation());
+      D.AddTypeInfo(DeclaratorChunk::getMemberPointer(
+                        SS, DS.getTypeQualifiers(), DS.getLocEnd()),
+                    std::move(DS.getAttributes()),
+                    /* Don't replace range end. */ SourceLocation());
       return;
     }
   }
 
   tok::TokenKind Kind = Tok.getKind();
 
   if (D.getDeclSpec().isTypeSpecPipe() && !isPipeDeclerator(D)) {
     DeclSpec DS(AttrFactory);
     ParseTypeQualifierListOpt(DS);
 
     D.AddTypeInfo(
         DeclaratorChunk::getPipe(DS.getTypeQualifiers(), DS.getPipeLoc()),
-        DS.getAttributes(), SourceLocation());
+        std::move(DS.getAttributes()), SourceLocation());
   }
 
   // Not a pointer, C++ reference, or block.
   if (!isPtrOperatorToken(Kind, getLangOpts(), D.getContext())) {
     if (DirectDeclParser)
       (this->*DirectDeclParser)(D);
     return;
   }
unsigned Reqs = AR_CXX11AttributesParsed | AR_DeclspecAttributesParsed |
                          : AR_GNUAttributesParsedAndRejected);
     ParseTypeQualifierListOpt(DS, Reqs, true, !D.mayOmitIdentifier());
     D.ExtendWithDeclSpec(DS);
 
     // Recursively parse the declarator.
     ParseDeclaratorInternal(D, DirectDeclParser);
     if (Kind == tok::star)
       // Remember that we parsed a pointer type, and remember the type-quals.
-      D.AddTypeInfo(DeclaratorChunk::getPointer(DS.getTypeQualifiers(), Loc,
-                                                DS.getConstSpecLoc(),
-                                                DS.getVolatileSpecLoc(),
-                                                DS.getRestrictSpecLoc(),
-                                                DS.getAtomicSpecLoc(),
-                                                DS.getUnalignedSpecLoc()),
-                    DS.getAttributes(),
-                    SourceLocation());
+      D.AddTypeInfo(DeclaratorChunk::getPointer(
+                        DS.getTypeQualifiers(), Loc, DS.getConstSpecLoc(),
+                        DS.getVolatileSpecLoc(), DS.getRestrictSpecLoc(),
+                        DS.getAtomicSpecLoc(), DS.getUnalignedSpecLoc()),
+                    std::move(DS.getAttributes()), SourceLocation());
     else
       // Remember that we parsed a Block type, and remember the type-quals.
-      D.AddTypeInfo(DeclaratorChunk::getBlockPointer(DS.getTypeQualifiers(),
-                                                     Loc),
-                    DS.getAttributes(),
-                    SourceLocation());
+      D.AddTypeInfo(
+          DeclaratorChunk::getBlockPointer(DS.getTypeQualifiers(), Loc),
+          std::move(DS.getAttributes()), SourceLocation());
   } else {
     // Is a reference
     DeclSpec DS(AttrFactory);
 
     // Complain about rvalue references in C++03, but then go on and build
     // the declarator.
     if (Kind == tok::ampamp)
       Diag(Loc, getLangOpts().CPlusPlus11 ?
if (D.getNumTypeObjects() > 0) {
         // can go ahead and build the (technically ill-formed)
         // declarator: reference collapsing will take care of it.
       }
     }
 
     // Remember that we parsed a reference type.
     D.AddTypeInfo(DeclaratorChunk::getReference(DS.getTypeQualifiers(), Loc,
                                                 Kind == tok::amp),
-                  DS.getAttributes(),
-                  SourceLocation());
+                  std::move(DS.getAttributes()), SourceLocation());
   }
 }
 
 // When correcting from misplaced brackets before the identifier, the location
 // is saved inside the declarator so that other diagnostic messages can use
 // them.  This extracts and returns that location, or returns the provided
 // location if a stored location does not exist.
 static SourceLocation getMissingDeclaratorIdLoc(Declarator &D,
if (isGrouping) {
     SourceLocation EllipsisLoc = D.getEllipsisLoc();
     D.setEllipsisLoc(SourceLocation());
 
     bool hadGroupingParens = D.hasGroupingParens();
     D.setGroupingParens(true);
     ParseDeclaratorInternal(D, &Parser::ParseDirectDeclarator);
     // Match the ')'.
     T.consumeClose();
-    D.AddTypeInfo(DeclaratorChunk::getParen(T.getOpenLocation(),
-                                            T.getCloseLocation()),
-                  attrs, T.getCloseLocation());
+    D.AddTypeInfo(
+        DeclaratorChunk::getParen(T.getOpenLocation(), T.getCloseLocation()),
+        std::move(attrs), T.getCloseLocation());
 
     D.setGroupingParens(hadGroupingParens);
 
     // An ellipsis cannot be placed outside parentheses.
     if (EllipsisLoc.isValid())
       DiagnoseMisplacedEllipsisInDeclarator(EllipsisLoc, D);
 
     return;
for (Decl *D : getCurScope()->decls()) {
       NamedDecl *ND = dyn_cast<NamedDecl>(D);
       if (!ND || isa<ParmVarDecl>(ND))
         continue;
       DeclsInPrototype.push_back(ND);
     }
   }
 
   // Remember that we parsed a function type, and remember the attributes.
-  D.AddTypeInfo(DeclaratorChunk::getFunction(HasProto,
-                                             IsAmbiguous,
-                                             LParenLoc,
-                                             ParamInfo.data(), ParamInfo.size(),
-                                             EllipsisLoc, RParenLoc,
-                                             DS.getTypeQualifiers(),
-                                             RefQualifierIsLValueRef,
-                                             RefQualifierLoc, ConstQualifierLoc,
-                                             VolatileQualifierLoc,
-                                             RestrictQualifierLoc,
-                                             /*MutableLoc=*/SourceLocation(),
-                                             ESpecType, ESpecRange,
-                                             DynamicExceptions.data(),
-                                             DynamicExceptionRanges.data(),
-                                             DynamicExceptions.size(),
-                                             NoexceptExpr.isUsable() ?
-                                               NoexceptExpr.get() : nullptr,
-                                             ExceptionSpecTokens,
-                                             DeclsInPrototype,
-                                             StartLoc, LocalEndLoc, D,
-                                             TrailingReturnType),
-                FnAttrs, EndLoc);
+  D.AddTypeInfo(DeclaratorChunk::getFunction(
+                    HasProto, IsAmbiguous, LParenLoc, ParamInfo.data(),
+                    ParamInfo.size(), EllipsisLoc, RParenLoc,
+                    DS.getTypeQualifiers(), RefQualifierIsLValueRef,
+                    RefQualifierLoc, ConstQualifierLoc, VolatileQualifierLoc,
+                    /*MutableLoc=*/SourceLocation(), ESpecType, ESpecRange,
+                    DynamicExceptions.data(), DynamicExceptionRanges.data(),
+                    NoexceptExpr.isUsable() ? NoexceptExpr.get() : nullptr,
+                    ExceptionSpecTokens, DeclsInPrototype, StartLoc,
+                    LocalEndLoc, D, TrailingReturnType),
+                std::move(FnAttrs), EndLoc);
 }
 
 /// ParseRefQualifier - Parses a member function ref-qualifier. Returns
 /// true if a ref-qualifier is found.
 bool Parser::ParseRefQualifier(bool &RefQualifierIsLValueRef,
                                SourceLocation &RefQualifierLoc) {
   if (Tok.isOneOf(tok::amp, tok::ampamp)) {
     Diag(Tok, getLangOpts().CPlusPlus11 ?
if (Tok.getKind() == tok::r_square) {
     T.consumeClose();
     ParsedAttributes attrs(AttrFactory);
     MaybeParseCXX11Attributes(attrs);
 
     // Remember that we parsed the empty array type.
     D.AddTypeInfo(DeclaratorChunk::getArray(0, false, false, nullptr,
                                             T.getOpenLocation(),
                                             T.getCloseLocation()),
-                  attrs, T.getCloseLocation());
+                  std::move(attrs), T.getCloseLocation());
     return;
   } else if (Tok.getKind() == tok::numeric_constant &&
              GetLookAheadToken(1).is(tok::r_square)) {
     // [4] is very common.  Parse the numeric constant expression.
     ExprResult ExprRes(Actions.ActOnNumericConstant(Tok, getCurScope()));
     ConsumeToken();
 
     T.consumeClose();
     ParsedAttributes attrs(AttrFactory);
     MaybeParseCXX11Attributes(attrs);
 
     // Remember that we parsed a array type, and remember its features.
-    D.AddTypeInfo(DeclaratorChunk::getArray(0, false, false,
-                                            ExprRes.get(),
+    D.AddTypeInfo(DeclaratorChunk::getArray(0, false, false, ExprRes.get(),
                                             T.getOpenLocation(),
                                             T.getCloseLocation()),
-                  attrs, T.getCloseLocation());
+                  std::move(attrs), T.getCloseLocation());
     return;
   } else if (Tok.getKind() == tok::code_completion) {
     Actions.CodeCompleteBracketDeclarator(getCurScope());
     return cutOffParsing();
   }
 
   // If valid, this location is the position where we read the 'static' keyword.
   SourceLocation StaticLoc;
if (NumElements.isInvalid()) {
     return;
   }
 
   T.consumeClose();
 
   MaybeParseCXX11Attributes(DS.getAttributes());
 
   // Remember that we parsed a array type, and remember its features.
-  D.AddTypeInfo(DeclaratorChunk::getArray(DS.getTypeQualifiers(),
-                                          StaticLoc.isValid(), isStar,
-                                          NumElements.get(),
-                                          T.getOpenLocation(),
-                                          T.getCloseLocation()),
-                DS.getAttributes(), T.getCloseLocation());
+  D.AddTypeInfo(
+      DeclaratorChunk::getArray(DS.getTypeQualifiers(), StaticLoc.isValid(),
+                                isStar, NumElements.get(), T.getOpenLocation(),
+      std::move(DS.getAttributes()), T.getCloseLocation());
 }
 
 /// Diagnose brackets before an identifier.
 void Parser::ParseMisplacedBracketDeclarator(Declarator &D) {
   assert(Tok.is(tok::l_square) && "Missing opening bracket");
   assert(!D.mayOmitIdentifier() && "Declarator cannot omit identifier");
 
   SourceLocation StartBracketLoc = Tok.getLocation();
if (D.getNumTypeObjects() != 0) {
     case DeclaratorChunk::Function:
     case DeclaratorChunk::Paren:
       break;
     }
   }
 
   if (NeedParens) {
     // Create a DeclaratorChunk for the inserted parens.
-    ParsedAttributes attrs(AttrFactory);
     SourceLocation EndLoc = PP.getLocForEndOfToken(D.getLocEnd());
-    D.AddTypeInfo(DeclaratorChunk::getParen(SuggestParenLoc, EndLoc), attrs,
+    D.AddTypeInfo(DeclaratorChunk::getParen(SuggestParenLoc, EndLoc),
                   SourceLocation());
   }
 
   // Adding back the bracket info to the end of the Declarator.
   for (unsigned i = 0, e = TempDeclarator.getNumTypeObjects(); i < e; ++i) {
     const DeclaratorChunk &Chunk = TempDeclarator.getTypeObject(i);
-    ParsedAttributes attrs(AttrFactory);
-    attrs.set(Chunk.Common.AttrList);
-    D.AddTypeInfo(Chunk, attrs, SourceLocation());
+    D.AddTypeInfo(Chunk, SourceLocation());
   }
 
   // The missing identifier would have been diagnosed in ParseDirectDeclarator.
   // If parentheses are required, always suggest them.
   if (!D.getIdentifier() && !NeedParens)
     return;
 
   SourceLocation EndBracketLoc = TempDeclarator.getLocEnd();

lib/Parse/ParseDeclCXX.cpp

Parser::DeclGroupPtrTy Parser::ParseNamespace(DeclaratorContext Context,
   if (InlineLoc.isValid())
     Diag(InlineLoc, getLangOpts().CPlusPlus11 ?
          diag::warn_cxx98_compat_inline_namespace : diag::ext_inline_namespace);
 
   // Enter a scope for the namespace.
   ParseScope NamespaceScope(this, Scope::DeclScope);
 
   UsingDirectiveDecl *ImplicitUsingDirectiveDecl = nullptr;
-  Decl *NamespcDecl =
-    Actions.ActOnStartNamespaceDef(getCurScope(), InlineLoc, NamespaceLoc,
-                                   IdentLoc, Ident, T.getOpenLocation(), 
-                                   attrs.getList(), ImplicitUsingDirectiveDecl);
+  Decl *NamespcDecl = Actions.ActOnStartNamespaceDef(
+      getCurScope(), InlineLoc, NamespaceLoc, IdentLoc, Ident,
+      T.getOpenLocation(), attrs, ImplicitUsingDirectiveDecl);
 
   PrettyDeclStackTraceEntry CrashInfo(Actions.Context, NamespcDecl,
                                       NamespaceLoc, "parsing namespace");
 
   // Parse the contents of the namespace.  This includes parsing recovery on 
   // any improperly nested namespaces.
   ParseInnerNamespace(ExtraIdentLoc, ExtraIdent, ExtraNamespaceLoc, 0,
                       InlineLoc, attrs, T);
if (index == Ident.size()) {
     return;
   }
 
   // Handle a nested namespace definition.
   // FIXME: Preserve the source information through to the AST rather than
   // desugaring it here.
   ParseScope NamespaceScope(this, Scope::DeclScope);
   UsingDirectiveDecl *ImplicitUsingDirectiveDecl = nullptr;
-  Decl *NamespcDecl =
-    Actions.ActOnStartNamespaceDef(getCurScope(), SourceLocation(),
-                                   NamespaceLoc[index], IdentLoc[index],
-                                   Ident[index], Tracker.getOpenLocation(), 
-                                   attrs.getList(), ImplicitUsingDirectiveDecl);
+  Decl *NamespcDecl = Actions.ActOnStartNamespaceDef(
+      getCurScope(), SourceLocation(), NamespaceLoc[index], IdentLoc[index],
+      Ident[index], Tracker.getOpenLocation(), attrs,
+      ImplicitUsingDirectiveDecl);
   assert(!ImplicitUsingDirectiveDecl && 
          "nested namespace definition cannot define anonymous namespace");
 
   ParseInnerNamespace(IdentLoc, Ident, NamespaceLoc, ++index, InlineLoc,
                       attrs, Tracker);
 
   NamespaceScope.Exit();
   Actions.ActOnFinishNamespaceDef(NamespcDecl, Tracker.getCloseLocation());
Decl *Parser::ParseUsingDirective(DeclaratorContext Context,
   // Eat ';'.
   DeclEnd = Tok.getLocation();
   if (ExpectAndConsume(tok::semi,
                        GNUAttr ? diag::err_expected_semi_after_attribute_list
                                : diag::err_expected_semi_after_namespace_name))
     SkipUntil(tok::semi);
 
   return Actions.ActOnUsingDirective(getCurScope(), UsingLoc, NamespcLoc, SS,
-                                     IdentLoc, NamespcName, attrs.getList());
+                                     IdentLoc, NamespcName, attrs);
 }
 
 /// Parse a using-declarator (or the identifier in a C++11 alias-declaration).
 ///
 ///     using-declarator:
 ///       'typename'[opt] nested-name-specifier unqualified-id
 ///
 bool Parser::ParseUsingDeclarator(DeclaratorContext Context,
else {
              diag::err_typename_identifiers_only)
             << FixItHint::CreateRemoval(SourceRange(D.TypenameLoc));
         // Proceed parsing, but discard the typename keyword.
         D.TypenameLoc = SourceLocation();
       }
 
       Decl *UD = Actions.ActOnUsingDeclaration(getCurScope(), AS, UsingLoc,
                                                D.TypenameLoc, D.SS, D.Name,
-                                               D.EllipsisLoc, Attrs.getList());
+                                               D.EllipsisLoc, Attrs);
       if (UD)
         DeclsInGroup.push_back(UD);
     }
 
     if (!TryConsumeToken(tok::comma))
       break;
 
     // Parse another using-declarator.
if (ExpectAndConsume(tok::semi, diag::err_expected_after,
                                       : "alias declaration"))
     SkipUntil(tok::semi);
 
   TemplateParameterLists *TemplateParams = TemplateInfo.TemplateParams;
   MultiTemplateParamsArg TemplateParamsArg(
     TemplateParams ? TemplateParams->data() : nullptr,
     TemplateParams ? TemplateParams->size() : 0);
   return Actions.ActOnAliasDeclaration(getCurScope(), AS, TemplateParamsArg,
-                                       UsingLoc, D.Name, Attrs.getList(),
-                                       TypeAlias, DeclFromDeclSpec);
+                                       UsingLoc, D.Name, Attrs, TypeAlias,
+                                       DeclFromDeclSpec);
 }
 
 /// ParseStaticAssertDeclaration - Parse C++0x or C11 static_assert-declaration.
 ///
 /// [C++0x] static_assert-declaration:
 ///           static_assert ( constant-expression  ,  string-literal  ) ;
 ///
 /// [C11]   static_assert-declaration:
if (TemplateId) {
     // or explicit instantiation.
     ASTTemplateArgsPtr TemplateArgsPtr(TemplateId->getTemplateArgs(),
                                        TemplateId->NumArgs);
     if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
         TUK == Sema::TUK_Declaration) {
       // This is an explicit instantiation of a class template.
       ProhibitAttributes(attrs);
 
-      TagOrTempResult
-        = Actions.ActOnExplicitInstantiation(getCurScope(),
-                                             TemplateInfo.ExternLoc,
-                                             TemplateInfo.TemplateLoc,
-                                             TagType,
-                                             StartLoc,
-                                             SS,
-                                             TemplateId->Template,
-                                             TemplateId->TemplateNameLoc,
-                                             TemplateId->LAngleLoc,
-                                             TemplateArgsPtr,
-                                             TemplateId->RAngleLoc,
-                                             attrs.getList());
+      TagOrTempResult = Actions.ActOnExplicitInstantiation(
+          getCurScope(), TemplateInfo.ExternLoc, TemplateInfo.TemplateLoc,
+          TagType, StartLoc, SS, TemplateId->Template,
+          TemplateId->TemplateNameLoc, TemplateId->LAngleLoc, TemplateArgsPtr,
+          TemplateId->RAngleLoc, attrs);
 
       // Friend template-ids are treated as references unless
       // they have template headers, in which case they're ill-formed
       // (FIXME: "template <class T> friend class A<T>::B<int>;").
       // We diagnose this error in ActOnClassTemplateSpecialization.
     } else if (TUK == Sema::TUK_Reference ||
                (TUK == Sema::TUK_Friend &&
                 TemplateInfo.Kind == ParsedTemplateInfo::NonTemplate)) {
       ProhibitAttributes(attrs);
       TypeResult = Actions.ActOnTagTemplateIdType(TUK, TagType, StartLoc,
                                                   TemplateId->SS,
                                                   TemplateId->TemplateKWLoc,
                                                   TemplateId->Template,
if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
               LAngleLoc, nullptr));
           TemplateParams = &FakedParamLists;
         }
       }
 
       // Build the class template specialization.
       TagOrTempResult = Actions.ActOnClassTemplateSpecialization(
           getCurScope(), TagType, TUK, StartLoc, DS.getModulePrivateSpecLoc(),
-          *TemplateId, attrs.getList(),
+          *TemplateId, attrs,
           MultiTemplateParamsArg(TemplateParams ? &(*TemplateParams)[0]
                                                 : nullptr,
                                  TemplateParams ? TemplateParams->size() : 0),
           &SkipBody);
     }
   } else if (TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation &&
              TUK == Sema::TUK_Declaration) {
     // Explicit instantiation of a member of a class template
     // specialization, e.g.,
     //
     //   template struct Outer<int>::Inner;
     //
     ProhibitAttributes(attrs);
 
-    TagOrTempResult
-      = Actions.ActOnExplicitInstantiation(getCurScope(),
-                                           TemplateInfo.ExternLoc,
-                                           TemplateInfo.TemplateLoc,
-                                           TagType, StartLoc, SS, Name,
-                                           NameLoc, attrs.getList());
+    TagOrTempResult = Actions.ActOnExplicitInstantiation(
+        getCurScope(), TemplateInfo.ExternLoc, TemplateInfo.TemplateLoc,
+        TagType, StartLoc, SS, Name, NameLoc, attrs);
   } else if (TUK == Sema::TUK_Friend &&
              TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate) {
     ProhibitAttributes(attrs);
 
-    TagOrTempResult =
-      Actions.ActOnTemplatedFriendTag(getCurScope(), DS.getFriendSpecLoc(),
-                                      TagType, StartLoc, SS,
-                                      Name, NameLoc, attrs.getList(),
-                                      MultiTemplateParamsArg(
-                                    TemplateParams? &(*TemplateParams)[0]
-                                                  : nullptr,
-                                 TemplateParams? TemplateParams->size() : 0));
+    TagOrTempResult = Actions.ActOnTemplatedFriendTag(
+        getCurScope(), DS.getFriendSpecLoc(), TagType, StartLoc, SS, Name,
+        NameLoc, attrs,
+        MultiTemplateParamsArg(TemplateParams ? &(*TemplateParams)[0] : nullptr,
+                               TemplateParams ? TemplateParams->size() : 0));
   } else {
     if (TUK != Sema::TUK_Declaration && TUK != Sema::TUK_Definition)
       ProhibitAttributes(attrs);
 
     if (TUK == Sema::TUK_Definition &&
         TemplateInfo.Kind == ParsedTemplateInfo::ExplicitInstantiation) {
       // If the declarator-id is not a template-id, issue a diagnostic and
       // recover by ignoring the 'template' keyword.
if (TemplateId) {
     if (TUK != Sema::TUK_Reference && TemplateParams)
       TParams =
         MultiTemplateParamsArg(&(*TemplateParams)[0], TemplateParams->size());
 
     stripTypeAttributesOffDeclSpec(attrs, DS, TUK);
 
     // Declaration or definition of a class type
     TagOrTempResult = Actions.ActOnTag(
-        getCurScope(), TagType, TUK, StartLoc, SS, Name, NameLoc,
-        attrs.getList(), AS, DS.getModulePrivateSpecLoc(), TParams, Owned,
-        IsDependent, SourceLocation(), false, clang::TypeResult(),
+        getCurScope(), TagType, TUK, StartLoc, SS, Name, NameLoc, attrs, AS,
+        DS.getModulePrivateSpecLoc(), TParams, Owned, IsDependent,
+        SourceLocation(), false, clang::TypeResult(),
         DSC == DeclSpecContext::DSC_type_specifier,
         DSC == DeclSpecContext::DSC_template_param ||
             DSC == DeclSpecContext::DSC_template_type_arg,
         &SkipBody);
 
     // If ActOnTag said the type was dependent, try again with the
     // less common call.
     if (IsDependent) {
else {
         DS.SetTypeSpecError();
         return;
       }
     }
   }
 
   if (!TagOrTempResult.isInvalid())
     // Delayed processing of attributes.
-    Actions.ProcessDeclAttributeDelayed(TagOrTempResult.get(), attrs.getList());
+    Actions.ProcessDeclAttributeDelayed(TagOrTempResult.get(), attrs);
 
   const char *PrevSpec = nullptr;
   unsigned DiagID;
   bool Result;
   if (!TypeResult.isInvalid()) {
     Result = DS.SetTypeSpecType(DeclSpec::TST_typename, StartLoc,
                                 NameLoc.isValid() ? NameLoc : StartLoc,
                                 PrevSpec, DiagID, TypeResult.get(), Policy);
bool Parser::ParseCXXMemberDeclaratorBeforeInitializer(
   // virt-specifier *after* the GNU attributes.
   if (BitfieldSize.isUnset() && VS.isUnset()) {
     ParseOptionalCXX11VirtSpecifierSeq(
         VS, getCurrentClass().IsInterface,
         DeclaratorInfo.getDeclSpec().getFriendSpecLoc());
     if (!VS.isUnset()) {
       // If we saw any GNU-style attributes that are known to GCC followed by a
       // virt-specifier, issue a GCC-compat warning.
-      const AttributeList *Attr = DeclaratorInfo.getAttributes();
-      while (Attr) {
-        if (Attr->isKnownToGCC() && !Attr->isCXX11Attribute())
-          Diag(Attr->getLoc(), diag::warn_gcc_attribute_location);
-        Attr = Attr->getNext();
-      }
+      for (const AttributeList &AL : DeclaratorInfo.getAttributes())
+        if (AL.isKnownToGCC() && !AL.isCXX11Attribute())
+          Diag(AL.getLoc(), diag::warn_gcc_attribute_location);
+
       MaybeParseAndDiagnoseDeclSpecAfterCXX11VirtSpecifierSeq(DeclaratorInfo, VS);
     }
   }
 
   // If this has neither a name nor a bit width, something has gone seriously
   // wrong. Skip until the semi-colon or }.
   if (!DeclaratorInfo.hasName() && BitfieldSize.isUnset()) {
     // If so, skip until the semi-colon or a }.

 ///       pure-specifier:
 ///         '= 0'
 ///
 ///       constant-initializer:
 ///         '=' constant-expression
 ///
 Parser::DeclGroupPtrTy
 Parser::ParseCXXClassMemberDeclaration(AccessSpecifier AS,
-                                       AttributeList *AccessAttrs,
+                                       ParsedAttributes &AccessAttrs,
                                        const ParsedTemplateInfo &TemplateInfo,
                                        ParsingDeclRAIIObject *TemplateDiags) {
   if (Tok.is(tok::at)) {
     if (getLangOpts().ObjC1 && NextToken().isObjCAtKeyword(tok::objc_defs))
       Diag(Tok, diag::err_at_defs_cxx);
     else
       Diag(Tok, diag::err_at_in_class);
 
if (isAccessDecl) {
         SkipUntil(tok::semi);
         return nullptr;
       }
 
       // FIXME: We should do something with the 'template' keyword here.
       return DeclGroupPtrTy::make(DeclGroupRef(Actions.ActOnUsingDeclaration(
           getCurScope(), AS, /*UsingLoc*/ SourceLocation(),
           /*TypenameLoc*/ SourceLocation(), SS, Name,
-          /*EllipsisLoc*/ SourceLocation(), /*AttrList*/ nullptr)));
+          /*EllipsisLoc*/ SourceLocation(),
+          /*AttrList*/ ParsedAttributesView())));
     }
   }
 
   // static_assert-declaration. A templated static_assert declaration is
   // diagnosed in Parser::ParseSingleDeclarationAfterTemplate.
   if (!TemplateInfo.Kind &&
       Tok.isOneOf(tok::kw_static_assert, tok::kw__Static_assert)) {
     SourceLocation DeclEnd;
     return DeclGroupPtrTy::make(
         DeclGroupRef(ParseStaticAssertDeclaration(DeclEnd)));
   }
 
   if (Tok.is(tok::kw_template)) {
     assert(!TemplateInfo.TemplateParams &&
            "Nested template improperly parsed?");
     ObjCDeclContextSwitch ObjCDC(*this);
     SourceLocation DeclEnd;
     return DeclGroupPtrTy::make(
         DeclGroupRef(ParseTemplateDeclarationOrSpecialization(
-            DeclaratorContext::MemberContext, DeclEnd, AS, AccessAttrs)));
+            DeclaratorContext::MemberContext, DeclEnd, AccessAttrs, AS)));
   }
 
   // Handle:  member-declaration ::= '__extension__' member-declaration
   if (Tok.is(tok::kw___extension__)) {
     // __extension__ silences extension warnings in the subexpression.
     ExtensionRAIIObject O(Diags);  // Use RAII to do this.
     ConsumeToken();
     return ParseCXXClassMemberDeclaration(AS, AccessAttrs,
                                           TemplateInfo, TemplateDiags);
   }
 
   ParsedAttributesWithRange attrs(AttrFactory);
-  ParsedAttributesWithRange FnAttrs(AttrFactory);
+  ParsedAttributesViewWithRange FnAttrs;
   // Optional C++11 attribute-specifier
   MaybeParseCXX11Attributes(attrs);
   // We need to keep these attributes for future diagnostic
   // before they are taken over by declaration specifier.
-  FnAttrs.addAll(attrs.getList());
+  FnAttrs.addAll(attrs.begin(), attrs.end());
   FnAttrs.Range = attrs.Range;
 
   MaybeParseMicrosoftAttributes(attrs);
 
   if (Tok.is(tok::kw_using)) {
     ProhibitAttributes(attrs);
 
     // Eat 'using'.
if (DS.isFriendSpecified()) {
                                                   VS, HasInClassInit);
 
       if (VarTemplateDecl *VT =
               ThisDecl ? dyn_cast<VarTemplateDecl>(ThisDecl) : nullptr)
         // Re-direct this decl to refer to the templated decl so that we can
         // initialize it.
         ThisDecl = VT->getTemplatedDecl();
 
-      if (ThisDecl && AccessAttrs)
+      if (ThisDecl)
         Actions.ProcessDeclAttributeList(getCurScope(), ThisDecl, AccessAttrs);
     }
 
     // Error recovery might have converted a non-static member into a static
     // member.
     if (HasInClassInit != ICIS_NoInit &&
         DeclaratorInfo.getDeclSpec().getStorageClassSpec() ==
             DeclSpec::SCS_static) {
       HasInClassInit = ICIS_NoInit;

 Parser::DeclGroupPtrTy Parser::ParseCXXClassMemberDeclarationWithPragmas(
     AccessSpecifier &AS, ParsedAttributesWithRange &AccessAttrs,
     DeclSpec::TST TagType, Decl *TagDecl) {
   ParenBraceBracketBalancer BalancerRAIIObj(*this);
 
   switch (Tok.getKind()) {
   case tok::kw___if_exists:
   case tok::kw___if_not_exists:
-    ParseMicrosoftIfExistsClassDeclaration(TagType, AS);
+    ParseMicrosoftIfExistsClassDeclaration(TagType, AccessAttrs, AS);
     return nullptr;
 
   case tok::semi:
     // Check for extraneous top-level semicolon.
     ConsumeExtraSemi(InsideStruct, TagType);
     return nullptr;
 
     // Handle pragmas that can appear as member declarations.
case tok::kw_private: {
     }
 
     // The Microsoft extension __interface does not permit non-public
     // access specifiers.
     if (TagType == DeclSpec::TST_interface && AS != AS_public) {
       Diag(ASLoc, diag::err_access_specifier_interface) << (AS == AS_protected);
     }
 
-    if (Actions.ActOnAccessSpecifier(NewAS, ASLoc, EndLoc,
-                                     AccessAttrs.getList())) {
+    if (Actions.ActOnAccessSpecifier(NewAS, ASLoc, EndLoc, AccessAttrs)) {
       // found another attribute than only annotations
       AccessAttrs.clear();
     }
 
     return nullptr;
   }
 
   case tok::annot_pragma_openmp:
     return ParseOpenMPDeclarativeDirectiveWithExtDecl(AS, AccessAttrs, TagType,
                                                       TagDecl);
 
   default:
-    return ParseCXXClassMemberDeclaration(AS, AccessAttrs.getList());
+    return ParseCXXClassMemberDeclaration(AS, AccessAttrs);
   }
 }
 
 /// ParseCXXMemberSpecification - Parse the class definition.
 ///
 ///       member-specification:
 ///         member-declaration member-specification[opt]
 ///         access-specifier ':' member-specification[opt]
void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
   }
 
   // If attributes exist after class contents, parse them.
   ParsedAttributes attrs(AttrFactory);
   MaybeParseGNUAttributes(attrs);
 
   if (TagDecl)
     Actions.ActOnFinishCXXMemberSpecification(getCurScope(), RecordLoc, TagDecl,
-                                              T.getOpenLocation(), 
-                                              T.getCloseLocation(),
-                                              attrs.getList());
+                                              T.getOpenLocation(),
+                                              T.getCloseLocation(), attrs);
 
   // C++11 [class.mem]p2:
   //   Within the class member-specification, the class is regarded as complete
   //   within function bodies, default arguments, exception-specifications, and
   //   brace-or-equal-initializers for non-static data members (including such
   //   things in nested classes).
   if (TagDecl && NonNestedClass) {
     // We are not inside a nested class. This class and its nested classes
if (ScopeName && ScopeName->getName() == "clang")
     NumArgs =
         ParseClangAttributeArgs(AttrName, AttrNameLoc, Attrs, EndLoc, ScopeName,
                                 ScopeLoc, Syntax);
   else
     NumArgs =
         ParseAttributeArgsCommon(AttrName, AttrNameLoc, Attrs, EndLoc,
                                  ScopeName, ScopeLoc, Syntax);
 
-  const AttributeList *Attr = Attrs.getList();
-  if (Attr && IsBuiltInOrStandardCXX11Attribute(AttrName, ScopeName)) {
+  if (!Attrs.empty() &&
+      IsBuiltInOrStandardCXX11Attribute(AttrName, ScopeName)) {
+    AttributeList &Attr = *Attrs.begin();
     // If the attribute is a standard or built-in attribute and we are
     // parsing an argument list, we need to determine whether this attribute
     // was allowed to have an argument list (such as [[deprecated]]), and how
     // many arguments were parsed (so we can diagnose on [[deprecated()]]).
-    if (Attr->getMaxArgs() && !NumArgs) {
+    if (Attr.getMaxArgs() && !NumArgs) {
       // The attribute was allowed to have arguments, but none were provided
       // even though the attribute parsed successfully. This is an error.
       Diag(LParenLoc, diag::err_attribute_requires_arguments) << AttrName;
-      Attr->setInvalid(true);
-    } else if (!Attr->getMaxArgs()) {
+      Attr.setInvalid(true);
+    } else if (!Attr.getMaxArgs()) {
       // The attribute parsed successfully, but was not allowed to have any
       // arguments. It doesn't matter whether any were provided -- the
       // presence of the argument list (even if empty) is diagnosed.
       Diag(LParenLoc, diag::err_cxx11_attribute_forbids_arguments)
           << AttrName
           << FixItHint::CreateRemoval(SourceRange(LParenLoc, *EndLoc));
-      Attr->setInvalid(true);
+      Attr.setInvalid(true);
     }
   }
   return true;
 }
 
 /// ParseCXX11AttributeSpecifier - Parse a C++11 or C2x attribute-specifier.
 ///
 /// [C++11] attribute-specifier:
do {
     }
 
     T.consumeClose();
     if (endLoc)
       *endLoc = T.getCloseLocation();
   } while (Tok.is(tok::l_square));
 }
 
-void Parser::ParseMicrosoftIfExistsClassDeclaration(DeclSpec::TST TagType,
-                                                    AccessSpecifier& CurAS) {
+void Parser::ParseMicrosoftIfExistsClassDeclaration(
+    DeclSpec::TST TagType, ParsedAttributes &AccessAttrs,
+    AccessSpecifier &CurAS) {
   IfExistsCondition Result;
   if (ParseMicrosoftIfExistsCondition(Result))
     return;
   
   BalancedDelimiterTracker Braces(*this, tok::l_brace);
   if (Braces.consumeOpen()) {
     Diag(Tok, diag::err_expected) << tok::l_brace;
     return;
void Parser::ParseMicrosoftIfExistsClassDeclaration(
   case IEB_Skip:
     Braces.skipToEnd();
     return;
   }
 
   while (Tok.isNot(tok::r_brace) && !isEofOrEom()) {
     // __if_exists, __if_not_exists can nest.
     if (Tok.isOneOf(tok::kw___if_exists, tok::kw___if_not_exists)) {
-      ParseMicrosoftIfExistsClassDeclaration((DeclSpec::TST)TagType, CurAS);
+      ParseMicrosoftIfExistsClassDeclaration((DeclSpec::TST)TagType,
+                                             AccessAttrs, CurAS);
       continue;
     }
 
     // Check for extraneous top-level semicolon.
     if (Tok.is(tok::semi)) {
       ConsumeExtraSemi(InsideStruct, TagType);
       continue;
     }
 
     AccessSpecifier AS = getAccessSpecifierIfPresent();
     if (AS != AS_none) {
       // Current token is a C++ access specifier.
       CurAS = AS;
       SourceLocation ASLoc = Tok.getLocation();
       ConsumeToken();
       if (Tok.is(tok::colon))
-        Actions.ActOnAccessSpecifier(AS, ASLoc, Tok.getLocation());
+        Actions.ActOnAccessSpecifier(AS, ASLoc, Tok.getLocation(),
+                                     ParsedAttributesView{});
       else
         Diag(Tok, diag::err_expected) << tok::colon;
       ConsumeToken();
       continue;
     }
 
     // Parse all the comma separated declarators.
-    ParseCXXClassMemberDeclaration(CurAS, nullptr);
+    ParseCXXClassMemberDeclaration(CurAS, AccessAttrs);
   }
   
   Braces.consumeClose();
 }

lib/Parse/ParseExpr.cpp

if (Tok.is(tok::l_paren)) {
     MaybeParseGNUAttributes(ParamInfo);
 
     // Inform sema that we are starting a block.
     Actions.ActOnBlockArguments(CaretLoc, ParamInfo, getCurScope());
   } else if (!Tok.is(tok::l_brace)) {
     ParseBlockId(CaretLoc);
   } else {
     // Otherwise, pretend we saw (void).
-    ParsedAttributes attrs(AttrFactory);
     SourceLocation NoLoc;
-    ParamInfo.AddTypeInfo(DeclaratorChunk::getFunction(/*HasProto=*/true,
-                                             /*IsAmbiguous=*/false,
-                                             /*RParenLoc=*/NoLoc,
-                                             /*ArgInfo=*/nullptr,
-                                             /*NumArgs=*/0,
-                                             /*EllipsisLoc=*/NoLoc,
-                                             /*RParenLoc=*/NoLoc,
-                                             /*TypeQuals=*/0,
-                                             /*RefQualifierIsLvalueRef=*/true,
-                                             /*RefQualifierLoc=*/NoLoc,
-                                             /*ConstQualifierLoc=*/NoLoc,
-                                             /*VolatileQualifierLoc=*/NoLoc,
-                                             /*RestrictQualifierLoc=*/NoLoc,
-                                             /*MutableLoc=*/NoLoc,
-                                             EST_None,
-                                             /*ESpecRange=*/SourceRange(),
-                                             /*Exceptions=*/nullptr,
-                                             /*ExceptionRanges=*/nullptr,
-                                             /*NumExceptions=*/0,
-                                             /*NoexceptExpr=*/nullptr,
-                                             /*ExceptionSpecTokens=*/nullptr,
-                                             /*DeclsInPrototype=*/None,
-                                             CaretLoc, CaretLoc,
-                                             ParamInfo),
-                          attrs, CaretLoc);
+    ParamInfo.AddTypeInfo(
+        DeclaratorChunk::getFunction(/*HasProto=*/true,
+                                     /*MutableLoc=*/NoLoc, EST_None,
+                                     /*DeclsInPrototype=*/None, CaretLoc,
+                                     CaretLoc, ParamInfo),
+        CaretLoc);
 
     MaybeParseGNUAttributes(ParamInfo);
 
     // Inform sema that we are starting a block.
     Actions.ActOnBlockArguments(CaretLoc, ParamInfo, getCurScope());
   }
 
 

lib/Parse/ParseExprCXX.cpp

if (getLangOpts().CUDA) {
     // "[...]", even if there is no "(...)" before the lambda body.
     MaybeParseGNUAttributes(D);
   }
 
   // Helper to emit a warning if we see a CUDA host/device/global attribute
   // after '(...)'. nvcc doesn't accept this.
   auto WarnIfHasCUDATargetAttr = [&] {
     if (getLangOpts().CUDA)
-      for (auto *A = Attr.getList(); A != nullptr; A = A->getNext())
-        if (A->getKind() == AttributeList::AT_CUDADevice ||
-            A->getKind() == AttributeList::AT_CUDAHost ||
-            A->getKind() == AttributeList::AT_CUDAGlobal)
-          Diag(A->getLoc(), diag::warn_cuda_attr_lambda_position)
-              << A->getName()->getName();
+      for (const AttributeList &A : Attr)
+        if (A.getKind() == AttributeList::AT_CUDADevice ||
+            A.getKind() == AttributeList::AT_CUDAHost ||
+            A.getKind() == AttributeList::AT_CUDAGlobal)
+          Diag(A.getLoc(), diag::warn_cuda_attr_lambda_position)
+              << A.getName()->getName();
   };
 
   TypeResult TrailingReturnType;
   if (Tok.is(tok::l_paren)) {
     ParseScope PrototypeScope(this,
                               Scope::FunctionPrototypeScope |
                               Scope::FunctionDeclarationScope |
                               Scope::DeclScope);
if (Tok.is(tok::arrow)) {
         DeclEndLoc = Range.getEnd();
     }
 
     PrototypeScope.Exit();
 
     WarnIfHasCUDATargetAttr();
 
     SourceLocation NoLoc;
-    D.AddTypeInfo(DeclaratorChunk::getFunction(/*hasProto=*/true,
-                                           /*isAmbiguous=*/false,
-                                           LParenLoc,
-                                           ParamInfo.data(), ParamInfo.size(),
-                                           EllipsisLoc, RParenLoc,
-                                           DS.getTypeQualifiers(),
-                                           /*RefQualifierIsLValueRef=*/true,
-                                           /*RefQualifierLoc=*/NoLoc,
-                                           /*ConstQualifierLoc=*/NoLoc,
-                                           /*VolatileQualifierLoc=*/NoLoc,
-                                           /*RestrictQualifierLoc=*/NoLoc,
-                                           MutableLoc,
-                                           ESpecType, ESpecRange,
-                                           DynamicExceptions.data(),
-                                           DynamicExceptionRanges.data(),
-                                           DynamicExceptions.size(),
-                                           NoexceptExpr.isUsable() ?
-                                             NoexceptExpr.get() : nullptr,
-                                           /*ExceptionSpecTokens*/nullptr,
-                                           /*DeclsInPrototype=*/None,
-                                           LParenLoc, FunLocalRangeEnd, D,
-                                           TrailingReturnType),
-                  Attr, DeclEndLoc);
+    D.AddTypeInfo(DeclaratorChunk::getFunction(
+                      /*hasProto=*/true,
+                      /*isAmbiguous=*/false, LParenLoc, ParamInfo.data(),
+                      ParamInfo.size(), EllipsisLoc, RParenLoc,
+                      /*RestrictQualifierLoc=*/NoLoc, MutableLoc, ESpecType,
+                      ESpecRange, DynamicExceptions.data(),
+                      DynamicExceptionRanges.data(), DynamicExceptions.size(),
+                      NoexceptExpr.isUsable() ? NoexceptExpr.get() : nullptr,
+                      /*ExceptionSpecTokens*/ nullptr,
+                      /*DeclsInPrototype=*/None, LParenLoc, FunLocalRangeEnd, D,
+                  std::move(Attr), DeclEndLoc);
   } else if (Tok.isOneOf(tok::kw_mutable, tok::arrow, tok::kw___attribute,
                          tok::kw_constexpr) ||
              (Tok.is(tok::l_square) && NextToken().is(tok::l_square))) {
     // It's common to forget that one needs '()' before 'mutable', an attribute
     // specifier, or the result type. Deal with this.
     unsigned TokKind = 0;
     switch (Tok.getKind()) {
     case tok::kw_mutable: TokKind = 0; break;
if (Tok.is(tok::arrow)) {
           ParseTrailingReturnType(Range, /*MayBeFollowedByDirectInit*/ false);
       if (Range.getEnd().isValid())
         DeclEndLoc = Range.getEnd();
     }
 
     WarnIfHasCUDATargetAttr();
 
     SourceLocation NoLoc;
-    D.AddTypeInfo(DeclaratorChunk::getFunction(/*hasProto=*/true,
-                                               /*isAmbiguous=*/false,
-                                               /*LParenLoc=*/NoLoc,
-                                               /*Params=*/nullptr,
-                                               /*NumParams=*/0,
-                                               /*EllipsisLoc=*/NoLoc,
-                                               /*RParenLoc=*/NoLoc,
-                                               /*TypeQuals=*/0,
-                                               /*RefQualifierIsLValueRef=*/true,
-                                               /*RefQualifierLoc=*/NoLoc,
-                                               /*ConstQualifierLoc=*/NoLoc,
-                                               /*VolatileQualifierLoc=*/NoLoc,
-                                               /*RestrictQualifierLoc=*/NoLoc,
-                                               MutableLoc,
-                                               EST_None,
-                                               /*ESpecRange=*/SourceRange(),
-                                               /*Exceptions=*/nullptr,
-                                               /*ExceptionRanges=*/nullptr,
-                                               /*NumExceptions=*/0,
-                                               /*NoexceptExpr=*/nullptr,
-                                               /*ExceptionSpecTokens=*/nullptr,
-                                               /*DeclsInPrototype=*/None,
-                                               DeclLoc, DeclEndLoc, D,
-                                               TrailingReturnType),
-                  Attr, DeclEndLoc);
+    D.AddTypeInfo(DeclaratorChunk::getFunction(
+                      /*hasProto=*/true,
+                      /*RestrictQualifierLoc=*/NoLoc, MutableLoc, EST_None,
+                      /*DeclsInPrototype=*/None, DeclLoc, DeclEndLoc, D,
+                  std::move(Attr), DeclEndLoc);
   }
 
   // FIXME: Rename BlockScope -> ClosureScope if we decide to continue using
   // it.
   unsigned ScopeFlags = Scope::BlockScope | Scope::FnScope | Scope::DeclScope |
                         Scope::CompoundStmtScope;
   ParseScope BodyScope(this, ScopeFlags);
 
while (Tok.is(tok::l_square)) {
     T.consumeClose();
 
     // Attributes here appertain to the array type. C++11 [expr.new]p5.
     ParsedAttributes Attrs(AttrFactory);
     MaybeParseCXX11Attributes(Attrs);
 
     D.AddTypeInfo(DeclaratorChunk::getArray(0,
                                             /*static=*/false, /*star=*/false,
-                                            Size.get(),
-                                            T.getOpenLocation(),
+                                            Size.get(), T.getOpenLocation(),
                                             T.getCloseLocation()),
-                  Attrs, T.getCloseLocation());
+                  std::move(Attrs), T.getCloseLocation());
 
     if (T.getCloseLocation().isInvalid())
       return;
   }
 }
 
 /// ParseExpressionListOrTypeId - Parse either an expression-list or a type-id.
 /// This ambiguity appears in the syntax of the C++ new operator.

lib/Parse/ParseObjc.cpp

if (Tok.is(tok::less) &&
         ParseObjCProtocolReferences(ProtocolRefs, ProtocolLocs, true, true,
                                     LAngleLoc, EndProtoLoc,
                                     /*consumeLastToken=*/true))
       return nullptr;
 
     Decl *CategoryType = Actions.ActOnStartCategoryInterface(
         AtLoc, nameId, nameLoc, typeParameterList, categoryId, categoryLoc,
         ProtocolRefs.data(), ProtocolRefs.size(), ProtocolLocs.data(),
-        EndProtoLoc, attrs.getList());
+        EndProtoLoc, attrs);
 
     if (Tok.is(tok::l_brace))
       ParseObjCClassInstanceVariables(CategoryType, tok::objc_private, AtLoc);
       
     ParseObjCInterfaceDeclList(tok::objc_not_keyword, CategoryType);
 
     return CategoryType;
   }
if (!ProtocolIdents.empty()) {
                                          LAngleLoc, EndProtoLoc,
                                          /*consumeLastToken=*/true)) {
     return nullptr;
   }
 
   if (Tok.isNot(tok::less))
     Actions.ActOnTypedefedProtocols(protocols, protocolLocs,
                                     superClassId, superClassLoc);
-  
-  Decl *ClsType =
-    Actions.ActOnStartClassInterface(getCurScope(), AtLoc, nameId, nameLoc, 
-                                     typeParameterList, superClassId, 
-                                     superClassLoc, 
-                                     typeArgs,
-                                     SourceRange(typeArgsLAngleLoc,
-                                                 typeArgsRAngleLoc),
-                                     protocols.data(), protocols.size(),
-                                     protocolLocs.data(),
-                                     EndProtoLoc, attrs.getList());
+  Decl *ClsType = Actions.ActOnStartClassInterface(
+      getCurScope(), AtLoc, nameId, nameLoc, typeParameterList, superClassId,
+      superClassLoc, typeArgs,
+      SourceRange(typeArgsLAngleLoc, typeArgsRAngleLoc), protocols.data(),
+      protocols.size(), protocolLocs.data(), EndProtoLoc, attrs);
 
   if (Tok.is(tok::l_brace))
     ParseObjCClassInstanceVariables(ClsType, tok::objc_protected, AtLoc);
 
   ParseObjCInterfaceDeclList(tok::objc_interface, ClsType);
 
   return ClsType;
 }
 
 /// Add an attribute for a context-sensitive type nullability to the given
 /// declarator.
 static void addContextSensitiveTypeNullability(Parser &P,
                                                Declarator &D,
                                                NullabilityKind nullability,
                                                SourceLocation nullabilityLoc,
                                                bool &addedToDeclSpec) {
   // Create the attribute.
-  auto getNullabilityAttr = [&]() -> AttributeList * {
-    return D.getAttributePool().create(
-             P.getNullabilityKeyword(nullability),
-             SourceRange(nullabilityLoc),
-             nullptr, SourceLocation(),
-             nullptr, 0,
-             AttributeList::AS_ContextSensitiveKeyword);
+  auto getNullabilityAttr = [&](AttributePool &Pool) -> AttributeList * {
+    return Pool.create(P.getNullabilityKeyword(nullability),
+                       SourceRange(nullabilityLoc), nullptr, SourceLocation(),
+                       nullptr, 0, AttributeList::AS_ContextSensitiveKeyword);
   };
 
   if (D.getNumTypeObjects() > 0) {
     // Add the attribute to the declarator chunk nearest the declarator.
-    auto nullabilityAttr = getNullabilityAttr();
-    DeclaratorChunk &chunk = D.getTypeObject(0);
-    nullabilityAttr->setNext(chunk.getAttrListRef());
-    chunk.getAttrListRef() = nullabilityAttr;
+    D.getTypeObject(0).getAttrs().addAtStart(
+        getNullabilityAttr(D.getAttributePool()));
   } else if (!addedToDeclSpec) {
     // Otherwise, just put it on the declaration specifiers (if one
     // isn't there already).
-    D.getMutableDeclSpec().addAttributes(getNullabilityAttr());
+    D.getMutableDeclSpec().getAttributes().addAtStart(
+        getNullabilityAttr(D.getMutableDeclSpec().getAttributes().getPool()));
     addedToDeclSpec = true;
   }
 }
 
 /// Parse an Objective-C type parameter list, if present, or capture
 /// the locations of the protocol identifiers for a list of protocol
 /// references.
 ///
while (1) {
 
     // If this wasn't a recognized qualifier, bail out.
     if (II) return;
   }
 }
 
 /// Take all the decl attributes out of the given list and add
 /// them to the given attribute set.
-static void takeDeclAttributes(ParsedAttributes &attrs,
-                               AttributeList *list) {
-  while (list) {
-    AttributeList *cur = list;
-    list = cur->getNext();
-
-    if (!cur->isUsedAsTypeAttr()) {
-      // Clear out the next pointer.  We're really completely
-      // destroying the internal invariants of the declarator here,
-      // but it doesn't matter because we're done with it.
-      cur->setNext(nullptr);
-      attrs.add(cur);
+static void takeDeclAttributes(ParsedAttributesView &attrs,
+                               ParsedAttributesView &from) {
+  for (auto &AL : llvm::reverse(from)) {
+    if (!AL.isUsedAsTypeAttr()) {
+      from.remove(&AL);
+      attrs.addAtStart(&AL);
     }
   }
 }
 
 /// takeDeclAttributes - Take all the decl attributes from the given
 /// declarator and add them to the given list.
 static void takeDeclAttributes(ParsedAttributes &attrs,
                                Declarator &D) {
   // First, take ownership of all attributes.
   attrs.getPool().takeAllFrom(D.getAttributePool());
   attrs.getPool().takeAllFrom(D.getDeclSpec().getAttributePool());
 
   // Now actually move the attributes over.
-  takeDeclAttributes(attrs, D.getDeclSpec().getAttributes().getList());
+  takeDeclAttributes(attrs, D.getMutableDeclSpec().getAttributes());
   takeDeclAttributes(attrs, D.getAttributes());
   for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i)
-    takeDeclAttributes(attrs,
-                  const_cast<AttributeList*>(D.getTypeObject(i).getAttrs()));
+    takeDeclAttributes(attrs, D.getTypeObject(i).getAttrs());
 }
 
 ///   objc-type-name:
 ///     '(' objc-type-qualifiers[opt] type-name ')'
 ///     '(' objc-type-qualifiers[opt] ')'
 ///
 ParsedType Parser::ParseObjCTypeName(ObjCDeclSpec &DS, 
                                      DeclaratorContext context,
Decl *Parser::ParseObjCMethodDecl(SourceLocation mLoc,
   SmallVector<DeclaratorChunk::ParamInfo, 8> CParamInfo;
   if (Tok.isNot(tok::colon)) {
     // If attributes exist after the method, parse them.
     if (getLangOpts().ObjC2)
       MaybeParseGNUAttributes(methodAttrs);
     MaybeParseCXX11Attributes(methodAttrs);
 
     Selector Sel = PP.getSelectorTable().getNullarySelector(SelIdent);
-    Decl *Result
-         = Actions.ActOnMethodDeclaration(getCurScope(), mLoc, Tok.getLocation(),
-                                          mType, DSRet, ReturnType, 
-                                          selLoc, Sel, nullptr,
-                                          CParamInfo.data(), CParamInfo.size(),
-                                          methodAttrs.getList(), MethodImplKind,
-                                          false, MethodDefinition);
+    Decl *Result = Actions.ActOnMethodDeclaration(
+        getCurScope(), mLoc, Tok.getLocation(), mType, DSRet, ReturnType,
+        selLoc, Sel, nullptr, CParamInfo.data(), CParamInfo.size(), methodAttrs,
+        MethodImplKind, false, MethodDefinition);
     PD.complete(Result);
     return Result;
   }
 
   SmallVector<IdentifierInfo *, 12> KeyIdents;
   SmallVector<SourceLocation, 12> KeyLocs;
   SmallVector<Sema::ObjCArgInfo, 12> ArgInfos;
   ParseScope PrototypeScope(this, Scope::FunctionPrototypeScope |
if (Tok.is(tok::l_paren)) // Parse the argument type if present.
                                        DeclaratorContext::ObjCParameterContext,
                                        &paramAttrs);
 
     // If attributes exist before the argument name, parse them.
     // Regardless, collect all the attributes we've parsed so far.
     if (getLangOpts().ObjC2)
       MaybeParseGNUAttributes(paramAttrs);
     MaybeParseCXX11Attributes(paramAttrs);
-    ArgInfo.ArgAttrs = paramAttrs.getList();
+    ArgInfo.ArgAttrs = paramAttrs;
 
     // Code completion for the next piece of the selector.
     if (Tok.is(tok::code_completion)) {
       KeyIdents.push_back(SelIdent);
       Actions.CodeCompleteObjCMethodDeclSelector(getCurScope(), 
                                                  mType == tok::minus,
                                                  /*AtParameterName=*/true,
                                                  ReturnType, KeyIdents);
if (getLangOpts().ObjC2)
     MaybeParseGNUAttributes(methodAttrs);
   MaybeParseCXX11Attributes(methodAttrs);
 
   if (KeyIdents.size() == 0)
     return nullptr;
 
   Selector Sel = PP.getSelectorTable().getSelector(KeyIdents.size(),
                                                    &KeyIdents[0]);
-  Decl *Result
-       = Actions.ActOnMethodDeclaration(getCurScope(), mLoc, Tok.getLocation(),
-                                        mType, DSRet, ReturnType, 
-                                        KeyLocs, Sel, &ArgInfos[0], 
-                                        CParamInfo.data(), CParamInfo.size(),
-                                        methodAttrs.getList(),
-                                        MethodImplKind, isVariadic, MethodDefinition);
-  
+  Decl *Result = Actions.ActOnMethodDeclaration(
+      getCurScope(), mLoc, Tok.getLocation(), mType, DSRet, ReturnType, KeyLocs,
+      Sel, &ArgInfos[0], CParamInfo.data(), CParamInfo.size(), methodAttrs,
   PD.complete(Result);
   return Result;
 }
 
 ///   objc-protocol-refs:
 ///     '<' identifier-list '>'
 ///
 bool Parser::
void Parser::HelperActionsForIvarDeclarations(Decl *interfaceDecl, SourceLocation atLoc,
   if (!RBraceMissing)
     T.consumeClose();
   
   Actions.ActOnObjCContainerStartDefinition(interfaceDecl);
   Actions.ActOnLastBitfield(T.getCloseLocation(), AllIvarDecls);
   Actions.ActOnObjCContainerFinishDefinition();
   // Call ActOnFields() even if we don't have any decls. This is useful
   // for code rewriting tools that need to be aware of the empty list.
-  Actions.ActOnFields(getCurScope(), atLoc, interfaceDecl,
-                      AllIvarDecls,
-                      T.getOpenLocation(), T.getCloseLocation(), nullptr);
+  Actions.ActOnFields(getCurScope(), atLoc, interfaceDecl, AllIvarDecls,
+                      T.getOpenLocation(), T.getCloseLocation(),
+                      ParsedAttributesView());
 }
 
 ///   objc-class-instance-variables:
 ///     '{' objc-instance-variable-decl-list[opt] '}'
 ///
 ///   objc-instance-variable-decl-list:
 ///     objc-visibility-spec
 ///     objc-instance-variable-decl ';'
Parser::ParseObjCAtProtocolDeclaration(SourceLocation AtLoc,
   if (expectIdentifier())
     return nullptr; // missing protocol name.
   // Save the protocol name, then consume it.
   IdentifierInfo *protocolName = Tok.getIdentifierInfo();
   SourceLocation nameLoc = ConsumeToken();
 
   if (TryConsumeToken(tok::semi)) { // forward declaration of one protocol.
     IdentifierLocPair ProtoInfo(protocolName, nameLoc);
-    return Actions.ActOnForwardProtocolDeclaration(AtLoc, ProtoInfo,
-                                                   attrs.getList());
+    return Actions.ActOnForwardProtocolDeclaration(AtLoc, ProtoInfo, attrs);
   }
 
   CheckNestedObjCContexts(AtLoc);
 
   if (Tok.is(tok::comma)) { // list of forward declarations.
     SmallVector<IdentifierLocPair, 8> ProtocolRefs;
     ProtocolRefs.push_back(std::make_pair(protocolName, nameLoc));
 
while (1) {
 
       if (Tok.isNot(tok::comma))
         break;
     }
     // Consume the ';'.
     if (ExpectAndConsume(tok::semi, diag::err_expected_after, "@protocol"))
       return nullptr;
 
-    return Actions.ActOnForwardProtocolDeclaration(AtLoc, ProtocolRefs,
-                                                   attrs.getList());
+    return Actions.ActOnForwardProtocolDeclaration(AtLoc, ProtocolRefs, attrs);
   }
 
   // Last, and definitely not least, parse a protocol declaration.
   SourceLocation LAngleLoc, EndProtoLoc;
 
   SmallVector<Decl *, 8> ProtocolRefs;
   SmallVector<SourceLocation, 8> ProtocolLocs;
   if (Tok.is(tok::less) &&
       ParseObjCProtocolReferences(ProtocolRefs, ProtocolLocs, false, true,
                                   LAngleLoc, EndProtoLoc,
                                   /*consumeLastToken=*/true))
     return nullptr;
 
-  Decl *ProtoType =
-    Actions.ActOnStartProtocolInterface(AtLoc, protocolName, nameLoc,
-                                        ProtocolRefs.data(),
-                                        ProtocolRefs.size(),
-                                        ProtocolLocs.data(),
-                                        EndProtoLoc, attrs.getList());
+  Decl *ProtoType = Actions.ActOnStartProtocolInterface(
+      AtLoc, protocolName, nameLoc, ProtocolRefs.data(), ProtocolRefs.size(),
+      ProtocolLocs.data(), EndProtoLoc, attrs);
 
   ParseObjCInterfaceDeclList(tok::objc_protocol, ProtoType);
   return Actions.ConvertDeclToDeclGroup(ProtoType);
 }
 
 ///   objc-implementation:
 ///     objc-class-implementation-prologue
 ///     objc-category-implementation-prologue

lib/Parse/ParsePragma.cpp

if (Tok.getIdentifierInfo()) {
             << FixItHint::CreateInsertion(InsertStartLoc, "__attribute__((")
             << FixItHint::CreateInsertion(Tok.getEndLoc(), "))");
       }
     }
     SkipToEnd();
     return;
   }
 
-  if (!Attrs.getList() || Attrs.getList()->isInvalid()) {
+  if (Attrs.empty() || Attrs.begin()->isInvalid()) {
     SkipToEnd();
     return;
   }
 
   // Ensure that we don't have more than one attribute.
-  if (Attrs.getList()->getNext()) {
-    SourceLocation Loc = Attrs.getList()->getNext()->getLoc();
+  if (Attrs.size() > 1) {
+    SourceLocation Loc = Attrs[1].getLoc();
     Diag(Loc, diag::err_pragma_attribute_multiple_attributes);
     SkipToEnd();
     return;
   }
 
-  if (!Attrs.getList()->isSupportedByPragmaAttribute()) {
+  AttributeList &Attribute = *Attrs.begin();
+  if (!Attribute.isSupportedByPragmaAttribute()) {
     Diag(PragmaLoc, diag::err_pragma_attribute_unsupported_attribute)
-        << Attrs.getList()->getName();
+        << Attribute.getName();
     SkipToEnd();
     return;
   }
-  AttributeList &Attribute = *Attrs.getList();
 
   // Parse the subject-list.
   if (!TryConsumeToken(tok::comma)) {
     createExpectedAttributeSubjectRulesTokenDiagnostic(
         diag::err_expected, Attribute,
         MissingAttributeSubjectRulesRecoveryPoint::Comma, *this)
         << tok::comma;
     SkipToEnd();
     return;

lib/Parse/ParseStmt.cpp

StmtResult Res = ParseStatementOrDeclarationAfterAttributes(
       Stmts, Allowed, TrailingElseLoc, Attrs);
 
   assert((Attrs.empty() || Res.isInvalid() || Res.isUsable()) &&
          "attributes on empty statement");
 
   if (Attrs.empty() || Res.isInvalid())
     return Res;
 
-  return Actions.ProcessStmtAttributes(Res.get(), Attrs.getList(), Attrs.Range);
+  return Actions.ProcessStmtAttributes(Res.get(), Attrs, Attrs.Range);
 }
 
 namespace {
 class StatementFilterCCC : public CorrectionCandidateCallback {
 public:
   StatementFilterCCC(Token nextTok) : NextToken(nextTok) {
     WantTypeSpecifiers = nextTok.isOneOf(tok::l_paren, tok::less, tok::l_square,
                                          tok::identifier, tok::star, tok::amp);
else if (isDeclarationStatement()) {
       // FIXME: We should do this whether or not we have a declaration
       // statement, but that doesn't work correctly (because ProhibitAttributes
       // can't handle GNU attributes), so only call it in the one case where
       // GNU attributes are allowed.
       SubStmt = ParseStatementOrDeclarationAfterAttributes(
           Stmts, /*Allowed=*/ACK_StatementsOpenMPNonStandalone, nullptr,
           TempAttrs);
       if (!TempAttrs.empty() && !SubStmt.isInvalid())
-        SubStmt = Actions.ProcessStmtAttributes(
-            SubStmt.get(), TempAttrs.getList(), TempAttrs.Range);
+        SubStmt = Actions.ProcessStmtAttributes(SubStmt.get(), TempAttrs,
+                                                TempAttrs.Range);
     } else {
       Diag(Tok, diag::err_expected_after) << "__attribute__" << tok::semi;
     }
   }
 
   // If we've not parsed a statement yet, parse one now.
   if (!SubStmt.isInvalid() && !SubStmt.isUsable())
     SubStmt = ParseStatement();
 
   // Broken substmt shouldn't prevent the label from being added to the AST.
   if (SubStmt.isInvalid())
     SubStmt = Actions.ActOnNullStmt(ColonLoc);
 
   LabelDecl *LD = Actions.LookupOrCreateLabel(IdentTok.getIdentifierInfo(),
                                               IdentTok.getLocation());
-  if (AttributeList *Attrs = attrs.getList()) {
-    Actions.ProcessDeclAttributeList(Actions.CurScope, LD, Attrs);
-    attrs.clear();
-  }
+  Actions.ProcessDeclAttributeList(Actions.CurScope, LD, attrs);
 
   return Actions.ActOnLabelStmt(IdentTok.getLocation(), LD, ColonLoc,
                                 SubStmt.get());
 }
 
 /// ParseCaseStatement
 ///       labeled-statement:
 ///         'case' constant-expression ':' statement

 }
 
 bool Parser::ParseOpenCLUnrollHintAttribute(ParsedAttributes &Attrs) {
   MaybeParseGNUAttributes(Attrs);
 
   if (Attrs.empty())
     return true;
 
-  if (Attrs.getList()->getKind() != AttributeList::AT_OpenCLUnrollHint)
+  if (Attrs.begin()->getKind() != AttributeList::AT_OpenCLUnrollHint)
     return true;
 
   if (!(Tok.is(tok::kw_for) || Tok.is(tok::kw_while) || Tok.is(tok::kw_do))) {
     Diag(Tok, diag::err_opencl_unroll_hint_on_non_loop);
     return false;
   }
   return true;
 }

lib/Parse/ParseTemplate.cpp

 #include "clang/Parse/RAIIObjectsForParser.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 using namespace clang;
 
 /// Parse a template declaration, explicit instantiation, or
 /// explicit specialization.
-Decl *
-Parser::ParseDeclarationStartingWithTemplate(DeclaratorContext Context,
-                                             SourceLocation &DeclEnd,
-                                             AccessSpecifier AS,
-                                             AttributeList *AccessAttrs) {
+Decl *Parser::ParseDeclarationStartingWithTemplate(
+    DeclaratorContext Context, SourceLocation &DeclEnd,
+    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
   ObjCDeclContextSwitch ObjCDC(*this);
   
   if (Tok.is(tok::kw_template) && NextToken().isNot(tok::less)) {
-    return ParseExplicitInstantiation(Context,
-                                      SourceLocation(), ConsumeToken(),
-                                      DeclEnd, AS);
+    return ParseExplicitInstantiation(Context, SourceLocation(), ConsumeToken(),
+                                      DeclEnd, AccessAttrs, AS);
   }
-  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AS,
-                                                  AccessAttrs);
+  return ParseTemplateDeclarationOrSpecialization(Context, DeclEnd, AccessAttrs,
+                                                  AS);
 }
 
-
-
 /// Parse a template declaration or an explicit specialization.
 ///
 /// Template declarations include one or more template parameter lists
 /// and either the function or class template declaration. Explicit
 /// specializations contain one or more 'template < >' prefixes
 /// followed by a (possibly templated) declaration. Since the
 /// syntactic form of both features is nearly identical, we parse all
 /// of the template headers together and let semantic analysis sort
 /// the declarations from the explicit specializations.
 ///
 ///       template-declaration: [C++ temp]
 ///         'export'[opt] 'template' '<' template-parameter-list '>' declaration
 ///
 ///       explicit-specialization: [ C++ temp.expl.spec]
 ///         'template' '<' '>' declaration
-Decl *
-Parser::ParseTemplateDeclarationOrSpecialization(DeclaratorContext Context,
-                                                 SourceLocation &DeclEnd,
-                                                 AccessSpecifier AS,
-                                                 AttributeList *AccessAttrs) {
+Decl *Parser::ParseTemplateDeclarationOrSpecialization(
+    DeclaratorContext Context, SourceLocation &DeclEnd,
+    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
   assert(Tok.isOneOf(tok::kw_export, tok::kw_template) &&
          "Token does not start a template declaration.");
 
   // Enter template-parameter scope.
   ParseScope TemplateParmScope(this, Scope::TemplateParamScope);
 
   // Tell the action that names should be checked in the context of
   // the declaration to come.
ParamLists.push_back(Actions.ActOnTemplateParameterList(
         CurTemplateDepthTracker.getDepth(), ExportLoc, TemplateLoc, LAngleLoc,
         TemplateParams, RAngleLoc, OptionalRequiresClauseConstraintER.get()));
   } while (Tok.isOneOf(tok::kw_export, tok::kw_template));
 
   unsigned NewFlags = getCurScope()->getFlags() & ~Scope::TemplateParamScope;
   ParseScopeFlags TemplateScopeFlags(this, NewFlags, isSpecialization);
 
   // Parse the actual template declaration.
-  return ParseSingleDeclarationAfterTemplate(Context,
-                                             ParsedTemplateInfo(&ParamLists,
-                                                             isSpecialization,
-                                                         LastParamListWasEmpty),
-                                             ParsingTemplateParams,
-                                             DeclEnd, AS, AccessAttrs);
+  return ParseSingleDeclarationAfterTemplate(
+      Context,
+      ParsedTemplateInfo(&ParamLists, isSpecialization, LastParamListWasEmpty),
+      ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
 }
 
 /// Parse a single declaration that declares a template,
 /// template specialization, or explicit instantiation of a template.
 ///
 /// \param DeclEnd will receive the source location of the last token
 /// within this declaration.
 ///
 /// \param AS the access specifier associated with this
 /// declaration. Will be AS_none for namespace-scope declarations.
 ///
 /// \returns the new declaration.
-Decl *
-Parser::ParseSingleDeclarationAfterTemplate(
-                                       DeclaratorContext Context,
-                                       const ParsedTemplateInfo &TemplateInfo,
-                                       ParsingDeclRAIIObject &DiagsFromTParams,
-                                       SourceLocation &DeclEnd,
-                                       AccessSpecifier AS,
-                                       AttributeList *AccessAttrs) {
+Decl *Parser::ParseSingleDeclarationAfterTemplate(
+    DeclaratorContext Context, const ParsedTemplateInfo &TemplateInfo,
+    ParsingDeclRAIIObject &DiagsFromTParams, SourceLocation &DeclEnd,
+    ParsedAttributes &AccessAttrs, AccessSpecifier AS) {
   assert(TemplateInfo.Kind != ParsedTemplateInfo::NonTemplate &&
          "Template information required");
 
   if (Tok.is(tok::kw_static_assert)) {
     // A static_assert declaration may not be templated.
     Diag(Tok.getLocation(), diag::err_templated_invalid_declaration)
       << TemplateInfo.getSourceRange();
     // Parse the static_assert declaration to improve error recovery.

 ///       explicit-instantiation:
 ///         'extern' [opt] 'template' declaration
 ///
 /// Note that the 'extern' is a GNU extension and C++11 feature.
 Decl *Parser::ParseExplicitInstantiation(DeclaratorContext Context,
                                          SourceLocation ExternLoc,
                                          SourceLocation TemplateLoc,
                                          SourceLocation &DeclEnd,
+                                         ParsedAttributes &AccessAttrs,
                                          AccessSpecifier AS) {
   // This isn't really required here.
   ParsingDeclRAIIObject
     ParsingTemplateParams(*this, ParsingDeclRAIIObject::NoParent);
 
-  return ParseSingleDeclarationAfterTemplate(Context,
-                                             ParsedTemplateInfo(ExternLoc,
-                                                                TemplateLoc),
-                                             ParsingTemplateParams,
-                                             DeclEnd, AS);
+  return ParseSingleDeclarationAfterTemplate(
+      Context, ParsedTemplateInfo(ExternLoc, TemplateLoc),
+      ParsingTemplateParams, DeclEnd, AccessAttrs, AS);
 }
 
 SourceRange Parser::ParsedTemplateInfo::getSourceRange() const {
   if (TemplateParams)
     return getTemplateParamsRange(TemplateParams->data(),
                                   TemplateParams->size());
 
   SourceRange R(TemplateLoc);

lib/Parse/Parser.cpp

Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
   case tok::annot_pragma_ms_pragma:
     HandlePragmaMSPragma();
     return nullptr;
   case tok::annot_pragma_dump:
     HandlePragmaDump();
     return nullptr;
   case tok::semi:
     // Either a C++11 empty-declaration or attribute-declaration.
-    SingleDecl = Actions.ActOnEmptyDeclaration(getCurScope(),
-                                               attrs.getList(),
-                                               Tok.getLocation());
+    SingleDecl =
+        Actions.ActOnEmptyDeclaration(getCurScope(), attrs, Tok.getLocation());
     ConsumeExtraSemi(OutsideFunction);
     break;
   case tok::r_brace:
     Diag(Tok, diag::err_extraneous_closing_brace);
     ConsumeBrace();
     return nullptr;
   case tok::eof:
     Diag(Tok, diag::err_expected_external_declaration);
if (getLangOpts().CPlusPlus && NextToken().is(tok::kw_template)) {
       // Extern templates
       SourceLocation ExternLoc = ConsumeToken();
       SourceLocation TemplateLoc = ConsumeToken();
       Diag(ExternLoc, getLangOpts().CPlusPlus11 ?
              diag::warn_cxx98_compat_extern_template :
              diag::ext_extern_template) << SourceRange(ExternLoc, TemplateLoc);
       SourceLocation DeclEnd;
       return Actions.ConvertDeclToDeclGroup(
-                  ParseExplicitInstantiation(DeclaratorContext::FileContext,
-                                             ExternLoc, TemplateLoc, DeclEnd));
+          ParseExplicitInstantiation(DeclaratorContext::FileContext, ExternLoc,
+                                     TemplateLoc, DeclEnd, attrs));
     }
     goto dont_know;
 
   case tok::kw___if_exists:
   case tok::kw___if_not_exists:
     ParseMicrosoftIfExistsExternalDeclaration();
     return nullptr;
 
if (Tok.isNot(tok::l_brace) &&
     // If we didn't find the '{', bail out.
     if (Tok.isNot(tok::l_brace))
       return nullptr;
   }
 
   // Check to make sure that any normal attributes are allowed to be on
   // a definition.  Late parsed attributes are checked at the end.
   if (Tok.isNot(tok::equal)) {
-    AttributeList *DtorAttrs = D.getAttributes();
-    while (DtorAttrs) {
-      if (DtorAttrs->isKnownToGCC() &&
-          !DtorAttrs->isCXX11Attribute()) {
-        Diag(DtorAttrs->getLoc(), diag::warn_attribute_on_function_definition)
-          << DtorAttrs->getName();
-      }
-      DtorAttrs = DtorAttrs->getNext();
-    }
+    for (const AttributeList &AL : D.getAttributes())
+      if (AL.isKnownToGCC() && !AL.isCXX11Attribute())
+        Diag(AL.getLoc(), diag::warn_attribute_on_function_definition)
+            << AL.getName();
   }
 
   // In delayed template parsing mode, for function template we consume the
   // tokens and store them for late parsing at the end of the translation unit.
   if (getLangOpts().DelayedTemplateParsing && Tok.isNot(tok::equal) &&
       TemplateInfo.Kind == ParsedTemplateInfo::Template &&
       Actions.canDelayFunctionBody(D)) {
     MultiTemplateParamsArg TemplateParameterLists(*TemplateInfo.TemplateParams);

lib/Sema/AttributeList.cpp

static size_t getFreeListIndexForSize(size_t size) {
   assert(size >= sizeof(AttributeList));
   assert((size % sizeof(void*)) == 0);
   return ((size - sizeof(AttributeList)) / sizeof(void*));
 }
 
 void *AttributeFactory::allocate(size_t size) {
   // Check for a previously reclaimed attribute.
   size_t index = getFreeListIndexForSize(size);
-  if (index < FreeLists.size()) {
-    if (AttributeList *attr = FreeLists[index]) {
-      FreeLists[index] = attr->NextInPool;
-      return attr;
-    }
-  }
+  if (index < FreeLists.size() && !FreeLists[index].empty()) {
+    AttributeList *attr = FreeLists[index].back();
+    FreeLists[index].pop_back();
 
   // Otherwise, allocate something new.
   return Alloc.Allocate(size, alignof(AttributeFactory));
 }
 
-void AttributeFactory::reclaimPool(AttributeList *cur) {
-  assert(cur && "reclaiming empty pool!");
-  do {
-    // Read this here, because we're going to overwrite NextInPool
-    // when we toss 'cur' into the appropriate queue.
-    AttributeList *next = cur->NextInPool;
-
-    size_t size = cur->allocated_size();
-    size_t freeListIndex = getFreeListIndexForSize(size);
+void AttributeFactory::deallocate(AttributeList *Attr) {
+  size_t size = Attr->allocated_size();
 
-    // Expand FreeLists to the appropriate size, if required.
-    if (freeListIndex >= FreeLists.size())
-      FreeLists.resize(freeListIndex+1);
+    FreeLists.resize(freeListIndex + 1);
 
-    // Add 'cur' to the appropriate free-list.
-    cur->NextInPool = FreeLists[freeListIndex];
-    FreeLists[freeListIndex] = cur;
-    
-    cur = next;
-  } while (cur);
-}
-
-void AttributePool::takePool(AttributeList *pool) {
-  assert(pool);
-
-  // Fast path:  this pool is empty.
-  if (!Head) {
-    Head = pool;
-    return;
-  }
-
-  // Reverse the pool onto the current head.  This optimizes for the
-  // pattern of pulling a lot of pools into a single pool.
-  do {
-    AttributeList *next = pool->NextInPool;
-    pool->NextInPool = Head;
-    Head = pool;
-    pool = next;
-  } while (pool);
+#if !NDEBUG
+  // In debug mode, zero out the attribute to help find memory overwriting.
+  memset(Attr, 0, size);
+#endif
+
+  // Add 'Attr' to the appropriate free-list.
+  FreeLists[freeListIndex].push_back(Attr);
+}
+
+void AttributeFactory::reclaimPool(AttributePool &cur) {
+  for (AttributeList *AL : cur.Attrs)
+    deallocate(AL);
+}
+
+void AttributePool::takePool(AttributePool &pool) {
+  Attrs.insert(Attrs.end(), pool.Attrs.begin(), pool.Attrs.end());
+  pool.Attrs.clear();
 }
 
 #include "clang/Sema/AttrParsedAttrKinds.inc"
 
 static StringRef normalizeAttrName(StringRef AttrName, StringRef ScopeName,
                                    AttributeList::Syntax SyntaxUsed) {
   // Normalize the attribute name, __foo__ becomes foo. This is only allowable
   // for GNU attributes.

lib/Sema/DeclSpec.cpp

DeclaratorChunk DeclaratorChunk::getFunction(bool hasProto,
                                              TypeResult TrailingReturnType) {
   assert(!(TypeQuals & DeclSpec::TQ_atomic) &&
          "function cannot have _Atomic qualifier");
 
   DeclaratorChunk I;
   I.Kind                        = Function;
   I.Loc                         = LocalRangeBegin;
   I.EndLoc                      = LocalRangeEnd;
-  I.Fun.AttrList                = nullptr;
   I.Fun.hasPrototype            = hasProto;
   I.Fun.isVariadic              = EllipsisLoc.isValid();
   I.Fun.isAmbiguous             = isAmbiguous;
   I.Fun.LParenLoc               = LParenLoc.getRawEncoding();
   I.Fun.EllipsisLoc             = EllipsisLoc.getRawEncoding();
   I.Fun.RParenLoc               = RParenLoc.getRawEncoding();
   I.Fun.DeleteParams            = false;
   I.Fun.TypeQuals               = TypeQuals;
bool DeclSpec::SetConstexprSpec(SourceLocation Loc, const char *&PrevSpec,
   ConstexprLoc = Loc;
   return false;
 }
 
 void DeclSpec::SaveWrittenBuiltinSpecs() {
   writtenBS.Sign = getTypeSpecSign();
   writtenBS.Width = getTypeSpecWidth();
   writtenBS.Type = getTypeSpecType();
   // Search the list of attributes for the presence of a mode attribute.
-  writtenBS.ModeAttr = false;
-  AttributeList* attrs = getAttributes().getList();
-  while (attrs) {
-    if (attrs->getKind() == AttributeList::AT_Mode) {
-      writtenBS.ModeAttr = true;
-      break;
-    }
-    attrs = attrs->getNext();
-  }
+  writtenBS.ModeAttr = getAttributes().hasAttribute(AttributeList::AT_Mode);
 }
 
 /// Finish - This does final analysis of the declspec, rejecting things like
 /// "_Imaginary" (lacking an FP type).  This returns a diagnostic to issue or
 /// diag::NUM_DIAGNOSTICS if there is no error.  After calling this method,
 /// DeclSpec is guaranteed self-consistent, even if an error occurred.
 void DeclSpec::Finish(Sema &S, const PrintingPolicy &Policy) {
   // Before possibly changing their values, save specs as written.

lib/Sema/SemaAttr.cpp

void Sema::ActOnPragmaAttributePop(SourceLocation PragmaLoc) {
   }
   PragmaAttributeStack.pop_back();
 }
 
 void Sema::AddPragmaAttributes(Scope *S, Decl *D) {
   if (PragmaAttributeStack.empty())
     return;
   for (auto &Entry : PragmaAttributeStack) {
-    const AttributeList *Attribute = Entry.Attribute;
+    AttributeList *Attribute = Entry.Attribute;
     assert(Attribute && "Expected an attribute");
 
     // Ensure that the attribute can be applied to the given declaration.
     bool Applies = false;
     for (const auto &Rule : Entry.MatchRules) {
       if (Attribute->appliesToDecl(D, Rule)) {
         Applies = true;
         break;
       }
     }
     if (!Applies)
       continue;
     Entry.IsUsed = true;
-    assert(!Attribute->getNext() && "Expected just one attribute");
     PragmaAttributeCurrentTargetDecl = D;
-    ProcessDeclAttributeList(S, D, Attribute);
+    ParsedAttributesView Attrs;
+    Attrs.addAtStart(Attribute);
+    ProcessDeclAttributeList(S, D, Attrs);
     PragmaAttributeCurrentTargetDecl = nullptr;
   }
 }
 
 void Sema::PrintPragmaAttributeInstantiationPoint() {
   assert(PragmaAttributeCurrentTargetDecl && "Expected an active declaration");
   Diags.Report(PragmaAttributeCurrentTargetDecl->getLocStart(),
                diag::note_pragma_attribute_applied_decl_here);

lib/Sema/SemaCUDA.cpp

ExprResult Sema::ActOnCUDAExecConfigExpr(Scope *S, SourceLocation LLLLoc,
   DeclRefExpr *ConfigDR = new (Context)
       DeclRefExpr(ConfigDecl, false, ConfigQTy, VK_LValue, LLLLoc);
   MarkFunctionReferenced(LLLLoc, ConfigDecl);
 
   return ActOnCallExpr(S, ConfigDR, LLLLoc, ExecConfig, GGGLoc, nullptr,
                        /*IsExecConfig=*/true);
 }
 
-Sema::CUDAFunctionTarget Sema::IdentifyCUDATarget(const AttributeList *Attr) {
+Sema::CUDAFunctionTarget
+Sema::IdentifyCUDATarget(const ParsedAttributesView &Attrs) {
   bool HasHostAttr = false;
   bool HasDeviceAttr = false;
   bool HasGlobalAttr = false;
   bool HasInvalidTargetAttr = false;
-  while (Attr) {
-    switch(Attr->getKind()){
+  for (const AttributeList &AL : Attrs) {
+    switch (AL.getKind()) {
     case AttributeList::AT_CUDAGlobal:
       HasGlobalAttr = true;
       break;
     case AttributeList::AT_CUDAHost:
       HasHostAttr = true;
       break;
     case AttributeList::AT_CUDADevice:
       HasDeviceAttr = true;
       break;
     case AttributeList::AT_CUDAInvalidTarget:
       HasInvalidTargetAttr = true;
       break;
     default:
       break;
     }
-    Attr = Attr->getNext();
   }
+
   if (HasInvalidTargetAttr)
     return CFT_InvalidTarget;
 
   if (HasGlobalAttr)
     return CFT_Global;
 
   if (HasHostAttr && HasDeviceAttr)
     return CFT_HostDevice;

lib/Sema/SemaDecl.cpp

Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS, DeclSpec &DS,
   // Attributes should be placed after tag to apply to type declaration.
   if (!DS.getAttributes().empty()) {
     DeclSpec::TST TypeSpecType = DS.getTypeSpecType();
     if (TypeSpecType == DeclSpec::TST_class ||
         TypeSpecType == DeclSpec::TST_struct ||
         TypeSpecType == DeclSpec::TST_interface ||
         TypeSpecType == DeclSpec::TST_union ||
         TypeSpecType == DeclSpec::TST_enum) {
-      for (AttributeList* attrs = DS.getAttributes().getList(); attrs;
-           attrs = attrs->getNext())
-        Diag(attrs->getLoc(), diag::warn_declspec_attribute_ignored)
-            << attrs->getName() << GetDiagnosticTypeSpecifierID(TypeSpecType);
+      for (const AttributeList &AL : DS.getAttributes())
+        Diag(AL.getLoc(), diag::warn_declspec_attribute_ignored)
+            << AL.getName() << GetDiagnosticTypeSpecifierID(TypeSpecType);
     }
   }
 
   return TagD;
 }
 
 /// We are trying to inject an anonymous member into the given scope;
 /// check if there's an existing declaration that can't be overloaded.
static bool shouldConsiderLinkage(const FunctionDecl *FD) {
   const DeclContext *DC = FD->getDeclContext()->getRedeclContext();
   if (DC->isFileContext() || DC->isFunctionOrMethod() ||
       isa<OMPDeclareReductionDecl>(DC))
     return true;
   if (DC->isRecord())
     return false;
   llvm_unreachable("Unexpected context");
 }
 
-static bool hasParsedAttr(Scope *S, const AttributeList *AttrList,
-                          AttributeList::Kind Kind) {
-  for (const AttributeList *L = AttrList; L; L = L->getNext())
-    if (L->getKind() == Kind)
-      return true;
-  return false;
-}
-
 static bool hasParsedAttr(Scope *S, const Declarator &PD,
                           AttributeList::Kind Kind) {
   // Check decl attributes on the DeclSpec.
-  if (hasParsedAttr(S, PD.getDeclSpec().getAttributes().getList(), Kind))
+  if (PD.getDeclSpec().getAttributes().hasAttribute(Kind))
     return true;
 
   // Walk the declarator structure, checking decl attributes that were in a type
   // position to the decl itself.
   for (unsigned I = 0, E = PD.getNumTypeObjects(); I != E; ++I) {
-    if (hasParsedAttr(S, PD.getTypeObject(I).getAttrs(), Kind))
+    if (PD.getTypeObject(I).getAttrs().hasAttribute(Kind))
       return true;
   }
 
   // Finally, check attributes on the decl itself.
-  return hasParsedAttr(S, PD.getAttributes(), Kind);
+  return PD.getAttributes().hasAttribute(Kind);
 }
 
 /// Adjust the \c DeclContext for a function or variable that might be a
 /// function-local external declaration.
 bool Sema::adjustContextForLocalExternDecl(DeclContext *&DC) {
   if (!DC->isFunctionOrMethod())
     return false;
 
Sema::ActOnCXXForRangeIdentifier(Scope *S, SourceLocation IdentLoc,
   DS.SetTypeSpecType(DeclSpec::TST_auto, IdentLoc, PrevSpec, DiagID,
                      getPrintingPolicy());
 
   Declarator D(DS, DeclaratorContext::ForContext);
   D.SetIdentifier(Ident, IdentLoc);
   D.takeAttributes(Attrs, AttrEnd);
 
   ParsedAttributes EmptyAttrs(Attrs.getPool().getFactory());
-  D.AddTypeInfo(DeclaratorChunk::getReference(0, IdentLoc, /*lvalue*/false),
-                EmptyAttrs, IdentLoc);
+  D.AddTypeInfo(DeclaratorChunk::getReference(0, IdentLoc, /*lvalue*/ false),
+                IdentLoc);
   Decl *Var = ActOnDeclarator(S, D);
   cast<VarDecl>(Var)->setCXXForRangeDecl(true);
   FinalizeDeclaration(Var);
   return ActOnDeclStmt(FinalizeDeclaratorGroup(S, DS, Var), IdentLoc,
                        AttrEnd.isValid() ? AttrEnd : IdentLoc);
 }
 
 void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {

 
 /// When we finish delayed parsing of an attribute, we must attach it to the
 /// relevant Decl.
 void Sema::ActOnFinishDelayedAttribute(Scope *S, Decl *D,
                                        ParsedAttributes &Attrs) {
   // Always attach attributes to the underlying decl.
   if (TemplateDecl *TD = dyn_cast<TemplateDecl>(D))
     D = TD->getTemplatedDecl();
-  ProcessDeclAttributeList(S, D, Attrs.getList());
+  ProcessDeclAttributeList(S, D, Attrs);
 
   if (CXXMethodDecl *Method = dyn_cast_or_null<CXXMethodDecl>(D))
     if (Method->isStatic())
       checkThisInStaticMemberFunctionAttributes(Method);
 }
 
 /// ImplicitlyDefineFunction - An undeclared identifier was used in a function
 /// call, forming a call to an implicitly defined function (per C99 6.5.1p2).
D.AddTypeInfo(DeclaratorChunk::getFunction(/*HasProto=*/false,
                                              /*EllipsisLoc=*/NoLoc,
                                              /*RParenLoc=*/NoLoc,
                                              /*TypeQuals=*/0,
                                              /*RefQualifierIsLvalueRef=*/true,
                                              /*RefQualifierLoc=*/NoLoc,
                                              /*ConstQualifierLoc=*/NoLoc,
                                              /*VolatileQualifierLoc=*/NoLoc,
                                              /*RestrictQualifierLoc=*/NoLoc,
-                                             /*MutableLoc=*/NoLoc,
-                                             EST_None,
+                                             /*MutableLoc=*/NoLoc, EST_None,
                                              /*ESpecRange=*/SourceRange(),
                                              /*Exceptions=*/nullptr,
                                              /*ExceptionRanges=*/nullptr,
                                              /*NumExceptions=*/0,
                                              /*NoexceptExpr=*/nullptr,
                                              /*ExceptionSpecTokens=*/nullptr,
-                                             /*DeclsInPrototype=*/None,
-                                             Loc, Loc, D),
-                DS.getAttributes(),
-                SourceLocation());
+                                             /*DeclsInPrototype=*/None, Loc,
+                                             Loc, D),
+                std::move(DS.getAttributes()), SourceLocation());
   D.SetIdentifier(&II, Loc);
 
   // Insert this function into the enclosing block scope.
   FunctionDecl *FD = cast<FunctionDecl>(ActOnDeclarator(BlockScope, D));
   FD->setImplicit();
 
   AddKnownFunctionAttributes(FD);
 

 /// \param IsTypeSpecifier \c true if this is a type-specifier (or
 /// trailing-type-specifier) other than one in an alias-declaration.
 ///
 /// \param SkipBody If non-null, will be set to indicate if the caller should
 /// skip the definition of this tag and treat it as if it were a declaration.
 Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                      SourceLocation KWLoc, CXXScopeSpec &SS,
                      IdentifierInfo *Name, SourceLocation NameLoc,
-                     AttributeList *Attr, AccessSpecifier AS,
+                     const ParsedAttributesView &Attrs, AccessSpecifier AS,
                      SourceLocation ModulePrivateLoc,
                      MultiTemplateParamsArg TemplateParameterLists,
                      bool &OwnedDecl, bool &IsDependent,
                      SourceLocation ScopedEnumKWLoc,
-                     bool ScopedEnumUsesClassTag,
-                     TypeResult UnderlyingType,
+                     bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                      bool IsTypeSpecifier, bool IsTemplateParamOrArg,
                      SkipBodyInfo *SkipBody) {
   // If this is not a definition, it must have a name.
   IdentifierInfo *OrigName = Name;
   assert((Name != nullptr || TUK == TUK_Definition) &&
          "Nameless record must be a definition!");
   assert(TemplateParameterLists.size() == 0 || TUK != TUK_Reference);
 
if (TemplateParameterList *TemplateParams =
       if (TemplateParams->size() > 0) {
         // This is a declaration or definition of a class template (which may
         // be a member of another template).
 
         if (Invalid)
           return nullptr;
 
         OwnedDecl = false;
-        DeclResult Result = CheckClassTemplate(S, TagSpec, TUK, KWLoc,
-                                               SS, Name, NameLoc, Attr,
-                                               TemplateParams, AS,
-                                               ModulePrivateLoc,
-                                               /*FriendLoc*/SourceLocation(),
-                                               TemplateParameterLists.size()-1,
-                                               TemplateParameterLists.data(),
-                                               SkipBody);
+        DeclResult Result = CheckClassTemplate(
+            S, TagSpec, TUK, KWLoc, SS, Name, NameLoc, Attrs, TemplateParams,
+            AS, ModulePrivateLoc,
+            /*FriendLoc*/ SourceLocation(), TemplateParameterLists.size() - 1,
+            TemplateParameterLists.data(), SkipBody);
         return Result.get();
       } else {
         // The "template<>" header is extraneous.
         Diag(TemplateParams->getTemplateLoc(), diag::err_template_tag_noparams)
           << TypeWithKeyword::getTagTypeKindName(Kind) << Name;
         isMemberSpecialization = true;
       }
     }
if (TagDecl *PrevTagDecl = dyn_cast<TagDecl>(PrevDecl)) {
           Diag(NameLoc, diag::ext_member_redeclared);
           Diag(PrevTagDecl->getLocation(), diag::note_previous_declaration);
         }
 
         if (!Invalid) {
           // If this is a use, just return the declaration we found, unless
           // we have attributes.
           if (TUK == TUK_Reference || TUK == TUK_Friend) {
-            if (Attr) {
+            if (!Attrs.empty()) {
               // FIXME: Diagnose these attributes. For now, we create a new
               // declaration to hold them.
             } else if (TUK == TUK_Reference &&
                        (PrevTagDecl->getFriendObjectKind() ==
                             Decl::FOK_Undeclared ||
                         PrevDecl->getOwningModule() != getCurrentModule()) &&
                        SS.isEmpty()) {
               // This declaration is a reference to an existing entity, but
if (!Invalid && SearchDC->isRecord())
     SetMemberAccessSpecifier(New, PrevDecl, AS);
 
   if (PrevDecl)
     CheckRedeclarationModuleOwnership(New, PrevDecl);
 
   if (TUK == TUK_Definition)
     New->startDefinition();
 
-  if (Attr)
-    ProcessDeclAttributeList(S, New, Attr);
+  ProcessDeclAttributeList(S, New, Attrs);
   AddPragmaAttributes(S, New);
 
   // If this has an identifier, add it to the scope stack.
   if (TUK == TUK_Friend) {
     // We might be replacing an existing declaration in the lookup tables;
     // if so, borrow its access specifier.
     if (PrevDecl)
       New->setAccess(PrevDecl->getAccess());
Ivar = ObjCIvarDecl::Create(Context, cast<ObjCContainerDecl>(CurContext),
                                                                DeclLoc),
                               ObjCIvarDecl::Private, BW,
                               true);
   AllIvarDecls.push_back(Ivar);
 }
 
 void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
                        ArrayRef<Decl *> Fields, SourceLocation LBrac,
-                       SourceLocation RBrac, AttributeList *Attr) {
+                       SourceLocation RBrac,
+                       const ParsedAttributesView &Attrs) {
   assert(EnclosingDecl && "missing record or interface decl");
 
   // If this is an Objective-C @implementation or category and we have
   // new fields here we should reset the layout of the interface since
   // it will now change.
   if (!Fields.empty() && isa<ObjCContainerDecl>(EnclosingDecl)) {
     ObjCContainerDecl *DC = cast<ObjCContainerDecl>(EnclosingDecl);
     switch (DC->getKind()) {
if (CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(Record)) {
         }
       }
     }
 
     if (!Completed)
       Record->completeDefinition();
 
     // Handle attributes before checking the layout.
-    if (Attr)
-      ProcessDeclAttributeList(S, Record, Attr);
+    ProcessDeclAttributeList(S, Record, Attrs);
 
     // We may have deferred checking for a deleted destructor. Check now.
     if (CXXRecordDecl *CXXRecord = dyn_cast<CXXRecordDecl>(Record)) {
       auto *Dtor = CXXRecord->getDestructor();
       if (Dtor && Dtor->isImplicit() &&
           ShouldDeleteSpecialMember(Dtor, CXXDestructor)) {
         CXXRecord->setImplicitDestructorIsDeleted();
         SetDeclDeleted(Dtor, CXXRecord->getLocation());
if (!PrevED->getDeclName() && !hasVisibleDefinition(PrevED, &Hidden)) {
     return Skip;
   }
 
   return SkipBodyInfo();
 }
 
 Decl *Sema::ActOnEnumConstant(Scope *S, Decl *theEnumDecl, Decl *lastEnumConst,
                               SourceLocation IdLoc, IdentifierInfo *Id,
-                              AttributeList *Attr,
+                              const ParsedAttributesView &Attrs,
                               SourceLocation EqualLoc, Expr *Val) {
   EnumDecl *TheEnumDecl = cast<EnumDecl>(theEnumDecl);
   EnumConstantDecl *LastEnumConst =
     cast_or_null<EnumConstantDecl>(lastEnumConst);
 
   // The scope passed in may not be a decl scope.  Zip up the scope tree until
   // we find one that is.
   S = getNonFieldDeclScope(S);
if (!isa<TagDecl>(PrevDecl) && isDeclInScope(PrevDecl, CurContext, S)) {
       else
         Diag(IdLoc, diag::err_redefinition) << Id;
       notePreviousDefinition(PrevDecl, IdLoc);
       return nullptr;
     }
   }
 
   // Process attributes.
-  if (Attr) ProcessDeclAttributeList(S, New, Attr);
+  ProcessDeclAttributeList(S, New, Attrs);
   AddPragmaAttributes(S, New);
 
   // Register this decl in the current scope stack.
   New->setAccess(TheEnumDecl->getAccess());
   PushOnScopeChains(New, S);
 
   ActOnDocumentableDecl(New);
 
bool Sema::IsValueInFlagEnum(const EnumDecl *ED, const llvm::APInt &Val,
   // While it's true that any value could be used as a mask, the assumption is
   // that a mask will have all of the insignificant bits set. Anything else is
   // likely a logic error.
   llvm::APInt FlagMask = ~FlagBits.zextOrTrunc(Val.getBitWidth());
   return !(FlagMask & Val) || (AllowMask && !(FlagMask & ~Val));
 }
 
 void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceRange BraceRange,
-                         Decl *EnumDeclX,
-                         ArrayRef<Decl *> Elements,
-                         Scope *S, AttributeList *Attr) {
+                         Decl *EnumDeclX, ArrayRef<Decl *> Elements, Scope *S,
+                         const ParsedAttributesView &Attrs) {
   EnumDecl *Enum = cast<EnumDecl>(EnumDeclX);
   QualType EnumType = Context.getTypeDeclType(Enum);
 
-  if (Attr)
-    ProcessDeclAttributeList(S, Enum, Attr);
+  ProcessDeclAttributeList(S, Enum, Attrs);
 
   if (Enum->isDependentType()) {
     for (unsigned i = 0, e = Elements.size(); i != e; ++i) {
       EnumConstantDecl *ECD =
         cast_or_null<EnumConstantDecl>(Elements[i]);
       if (!ECD) continue;
 
       ECD->setType(EnumType);

lib/Sema/SemaDeclAttr.cpp

 // Top Level Sema Entry Points
 //===----------------------------------------------------------------------===//
 
 /// ProcessDeclAttribute - Apply the specific attribute to the specified decl if
 /// the attribute applies to decls.  If the attribute is a type attribute, just
 /// silently ignore it if a GNU attribute.
 static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
                                  const AttributeList &AL,
                                  bool IncludeCXX11Attributes) {
   if (AL.isInvalid() || AL.getKind() == AttributeList::IgnoredAttribute)
     return;
 
   // Ignore C++11 attributes on declarator chunks: they appertain to the type
   // instead.
   if (AL.isCXX11Attribute() && !IncludeCXX11Attributes)
     return;
 
   // Unknown attributes are automatically warned on. Target-specific attributes
   // which do not apply to the current target architecture are treated as
   // though they were unknown attributes.
   if (AL.getKind() == AttributeList::UnknownAttribute ||
       !AL.existsInTarget(S.Context.getTargetInfo())) {
     S.Diag(AL.getLoc(), AL.isDeclspecAttribute()
-                              ? diag::warn_unhandled_ms_attribute_ignored
-                              : diag::warn_unknown_attribute_ignored)
         << AL.getName();
     return;
   }
 
   if (handleCommonAttributeFeatures(S, D, AL))
     return;
 
   switch (AL.getKind()) {
static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_CUDAGlobal:
     handleGlobalAttr(S, D, AL);
     break;
   case AttributeList::AT_CUDADevice:
     handleSimpleAttributeWithExclusions<CUDADeviceAttr, CUDAGlobalAttr>(S, D,
                                                                         AL);
     break;
   case AttributeList::AT_CUDAHost:
-    handleSimpleAttributeWithExclusions<CUDAHostAttr, CUDAGlobalAttr>(S, D,
-                                                                      AL);
+    handleSimpleAttributeWithExclusions<CUDAHostAttr, CUDAGlobalAttr>(S, D, AL);
     break;
   case AttributeList::AT_GNUInline:
     handleGNUInlineAttr(S, D, AL);
     break;
   case AttributeList::AT_CUDALaunchBounds:
     handleLaunchBoundsAttr(S, D, AL);
     break;
   case AttributeList::AT_Restrict:
case AttributeList::AT_ObjCBridgeRelated:
     break;
   case AttributeList::AT_ObjCDesignatedInitializer:
     handleObjCDesignatedInitializer(S, D, AL);
     break;
   case AttributeList::AT_ObjCRuntimeName:
     handleObjCRuntimeName(S, D, AL);
     break;
    case AttributeList::AT_ObjCRuntimeVisible:
      handleSimpleAttribute<ObjCRuntimeVisibleAttr>(S, D, AL);
      break;
   case AttributeList::AT_ObjCBoxable:
     handleObjCBoxable(S, D, AL);
     break;
   case AttributeList::AT_CFAuditedTransfer:
     handleSimpleAttributeWithExclusions<CFAuditedTransferAttr,
                                         CFUnknownTransferAttr>(S, D, AL);
     break;
   case AttributeList::AT_CFUnknownTransfer:
case AttributeList::AT_ObjCRequiresPropertyDefs:
     break;
   case AttributeList::AT_Unused:
     handleUnusedAttr(S, D, AL);
     break;
   case AttributeList::AT_ReturnsTwice:
     handleSimpleAttribute<ReturnsTwiceAttr>(S, D, AL);
     break;
   case AttributeList::AT_NotTailCalled:
-    handleSimpleAttributeWithExclusions<NotTailCalledAttr,
-                                        AlwaysInlineAttr>(S, D, AL);
+    handleSimpleAttributeWithExclusions<NotTailCalledAttr, AlwaysInlineAttr>(
+        S, D, AL);
     break;
   case AttributeList::AT_DisableTailCalls:
-    handleSimpleAttributeWithExclusions<DisableTailCallsAttr,
-                                        NakedAttr>(S, D, AL);
+    handleSimpleAttributeWithExclusions<DisableTailCallsAttr, NakedAttr>(S, D,
+                                                                         AL);
     break;
   case AttributeList::AT_Used:
     handleSimpleAttribute<UsedAttr>(S, D, AL);
     break;
   case AttributeList::AT_Visibility:
     handleVisibilityAttr(S, D, AL, false);
     break;
   case AttributeList::AT_TypeVisibility:
case AttributeList::AT_XRayLogArgs:
     handleXRayLogArgsAttr(S, D, AL);
     break;
   }
 }
 
 /// ProcessDeclAttributeList - Apply all the decl attributes in the specified
 /// attribute list to the specified decl, ignoring any type attributes.
 void Sema::ProcessDeclAttributeList(Scope *S, Decl *D,
-                                    const AttributeList *AttrList,
+                                    const ParsedAttributesView &AttrList,
                                     bool IncludeCXX11Attributes) {
-  for (const AttributeList* l = AttrList; l; l = l->getNext())
-    ProcessDeclAttribute(*this, S, D, *l, IncludeCXX11Attributes);
+  if (AttrList.empty())
+    return;
+
+  for (const AttributeList &AL : AttrList)
+    ProcessDeclAttribute(*this, S, D, AL, IncludeCXX11Attributes);
 
   // FIXME: We should be able to handle these cases in TableGen.
   // GCC accepts
   // static int a9 __attribute__((weakref));
   // but that looks really pointless. We reject it.
   if (D->hasAttr<WeakRefAttr>() && !D->hasAttr<AliasAttr>()) {
-    Diag(AttrList->getLoc(), diag::err_attribute_weakref_without_alias)
+    Diag(AttrList.begin()->getLoc(), diag::err_attribute_weakref_without_alias)
         << cast<NamedDecl>(D);
     D->dropAttr<WeakRefAttr>();
     return;
   }
 
   // FIXME: We should be able to handle this in TableGen as well. It would be
   // good to have a way to specify "these attributes must appear as a group",
   // for these. Additionally, it would be good to have a way to specify "these
   // attribute must never appear as a group" for attributes like cold and hot.
if (const auto *A = D->getAttr<ReqdWorkGroupSizeAttr>()) {
             << A << ExpectedKernelFunction;
         D->setInvalidDecl();
       }
     }
   }
 }
 
 // Helper for delayed processing TransparentUnion attribute.
-void Sema::ProcessDeclAttributeDelayed(Decl *D, const AttributeList *AttrList) {
-  for (const AttributeList *AL = AttrList; AL; AL = AL->getNext())
-    if (AL->getKind() == AttributeList::AT_TransparentUnion) {
-      handleTransparentUnionAttr(*this, D, *AL);
+void Sema::ProcessDeclAttributeDelayed(Decl *D,
+                                       const ParsedAttributesView &AttrList) {
+  for (const AttributeList &AL : AttrList)
+    if (AL.getKind() == AttributeList::AT_TransparentUnion) {
+      handleTransparentUnionAttr(*this, D, AL);
       break;
     }
 }
 
 // Annotation attributes are the only attributes allowed after an access
 // specifier.
-bool Sema::ProcessAccessDeclAttributeList(AccessSpecDecl *ASDecl,
-                                          const AttributeList *AttrList) {
-  for (const AttributeList* l = AttrList; l; l = l->getNext()) {
-    if (l->getKind() == AttributeList::AT_Annotate) {
-      ProcessDeclAttribute(*this, nullptr, ASDecl, *l, l->isCXX11Attribute());
+bool Sema::ProcessAccessDeclAttributeList(
+    AccessSpecDecl *ASDecl, const ParsedAttributesView &AttrList) {
+  for (const AttributeList &AL : AttrList) {
+    if (AL.getKind() == AttributeList::AT_Annotate) {
+      ProcessDeclAttribute(*this, nullptr, ASDecl, AL, AL.isCXX11Attribute());
     } else {
-      Diag(l->getLoc(), diag::err_only_annotate_after_access_spec);
+      Diag(AL.getLoc(), diag::err_only_annotate_after_access_spec);
       return true;
     }
   }
-
   return false;
 }
 
 /// checkUnusedDeclAttributes - Check a list of attributes to see if it
 /// contains any decl attributes that we should warn about.
-static void checkUnusedDeclAttributes(Sema &S, const AttributeList *A) {
-  for ( ; A; A = A->getNext()) {
+static void checkUnusedDeclAttributes(Sema &S, const ParsedAttributesView &A) {
+  for (const AttributeList &AL : A) {
     // Only warn if the attribute is an unignored, non-type attribute.
-    if (A->isUsedAsTypeAttr() || A->isInvalid()) continue;
-    if (A->getKind() == AttributeList::IgnoredAttribute) continue;
+    if (AL.isUsedAsTypeAttr() || AL.isInvalid())
+      continue;
+    if (AL.getKind() == AttributeList::IgnoredAttribute)
+      continue;
 
-    if (A->getKind() == AttributeList::UnknownAttribute) {
-      S.Diag(A->getLoc(), diag::warn_unknown_attribute_ignored)
-        << A->getName() << A->getRange();
+    if (AL.getKind() == AttributeList::UnknownAttribute) {
+      S.Diag(AL.getLoc(), diag::warn_unknown_attribute_ignored)
+          << AL.getName() << AL.getRange();
     } else {
-      S.Diag(A->getLoc(), diag::warn_attribute_not_on_decl)
-        << A->getName() << A->getRange();
+      S.Diag(AL.getLoc(), diag::warn_attribute_not_on_decl)
+          << AL.getName() << AL.getRange();
     }
   }
 }
 
 /// checkUnusedDeclAttributes - Given a declarator which is not being
 /// used to build a declaration, complain about any decl attributes
 /// which might be lying around on it.
 void Sema::checkUnusedDeclAttributes(Declarator &D) {
-  ::checkUnusedDeclAttributes(*this, D.getDeclSpec().getAttributes().getList());
+  ::checkUnusedDeclAttributes(*this, D.getDeclSpec().getAttributes());
   ::checkUnusedDeclAttributes(*this, D.getAttributes());
   for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i)
     ::checkUnusedDeclAttributes(*this, D.getTypeObject(i).getAttrs());
 }
 
 /// DeclClonePragmaWeak - clone existing decl (maybe definition),
 /// \#pragma weak needs a non-definition decl and source may not have one.
 NamedDecl * Sema::DeclClonePragmaWeak(NamedDecl *ND, IdentifierInfo *II,
void Sema::ProcessPragmaWeak(Scope *S, Decl *D) {
   }
 }
 
 /// ProcessDeclAttributes - Given a declarator (PD) with attributes indicated in
 /// it, apply them to D.  This is a bit tricky because PD can have attributes
 /// specified in many different places, and we need to find and apply them all.
 void Sema::ProcessDeclAttributes(Scope *S, Decl *D, const Declarator &PD) {
   // Apply decl attributes from the DeclSpec if present.
-  if (const AttributeList *Attrs = PD.getDeclSpec().getAttributes().getList())
-    ProcessDeclAttributeList(S, D, Attrs);
+  if (!PD.getDeclSpec().getAttributes().empty())
+    ProcessDeclAttributeList(S, D, PD.getDeclSpec().getAttributes());
 
   // Walk the declarator structure, applying decl attributes that were in a type
   // position to the decl itself.  This handles cases like:
   //   int *__attr__(x)** D;
   // when X is a decl attribute.
   for (unsigned i = 0, e = PD.getNumTypeObjects(); i != e; ++i)
-    if (const AttributeList *Attrs = PD.getTypeObject(i).getAttrs())
-      ProcessDeclAttributeList(S, D, Attrs, /*IncludeCXX11Attributes=*/false);
+    ProcessDeclAttributeList(S, D, PD.getTypeObject(i).getAttrs(),
+                             /*IncludeCXX11Attributes=*/false);
 
   // Finally, apply any attributes on the decl itself.
-  if (const AttributeList *Attrs = PD.getAttributes())
-    ProcessDeclAttributeList(S, D, Attrs);
+  ProcessDeclAttributeList(S, D, PD.getAttributes());
 
   // Apply additional attributes specified by '#pragma clang attribute'.
   AddPragmaAttributes(S, D);
 }
 
 /// Is the given declaration allowed to use a forbidden type?
 /// If so, it'll still be annotated with an attribute that makes it
 /// illegal to actually use.

lib/Sema/SemaDeclCXX.cpp

Sema::ActOnBaseSpecifier(Decl *classdecl, SourceRange SpecifierRange,
   if (!Class)
     return true;
 
   // We haven't yet attached the base specifiers.
   Class->setIsParsingBaseSpecifiers();
 
   // We do not support any C++11 attributes on base-specifiers yet.
   // Diagnose any attributes we see.
-  if (!Attributes.empty()) {
-    for (AttributeList *Attr = Attributes.getList(); Attr;
-         Attr = Attr->getNext()) {
-      if (Attr->isInvalid() ||
-          Attr->getKind() == AttributeList::IgnoredAttribute)
-        continue;
-      Diag(Attr->getLoc(),
-           Attr->getKind() == AttributeList::UnknownAttribute
+  for (const AttributeList &AL : Attributes) {
+    if (AL.isInvalid() || AL.getKind() == AttributeList::IgnoredAttribute)
+    Diag(AL.getLoc(), AL.getKind() == AttributeList::UnknownAttribute
                           ? diag::warn_unknown_attribute_ignored
                           : diag::err_base_specifier_attribute)
-        << Attr->getName();
-    }
+        << AL.getName();
   }
 
   TypeSourceInfo *TInfo = nullptr;
   GetTypeFromParser(basetype, &TInfo);
 
   if (EllipsisLoc.isInvalid() &&
       DiagnoseUnexpandedParameterPack(SpecifierRange.getBegin(), TInfo,
                                       UPPC_BaseType))
std::string Sema::getAmbiguousPathsDisplayString(CXXBasePaths &Paths) {
   return PathDisplayStr;
 }
 
 //===----------------------------------------------------------------------===//
 // C++ class member Handling
 //===----------------------------------------------------------------------===//
 
 /// ActOnAccessSpecifier - Parsed an access specifier followed by a colon.
-bool Sema::ActOnAccessSpecifier(AccessSpecifier Access,
-                                SourceLocation ASLoc,
+bool Sema::ActOnAccessSpecifier(AccessSpecifier Access, SourceLocation ASLoc,
                                 SourceLocation ColonLoc,
-                                AttributeList *Attrs) {
+                                const ParsedAttributesView &Attrs) {
   assert(Access != AS_none && "Invalid kind for syntactic access specifier!");
   AccessSpecDecl *ASDecl = AccessSpecDecl::Create(Context, Access, CurContext,
                                                   ASLoc, ColonLoc);
   CurContext->addHiddenDecl(ASDecl);
   return ProcessAccessDeclAttributeList(ASDecl, Attrs);
 }
 
 /// CheckOverrideControl - Check C++11 override control semantics.
static bool InitializationHasSideEffects(const FieldDecl &FD) {
   // FIXME: Destruction of ObjC lifetime types has side-effects.
   if (const CXXRecordDecl *RD = T->getAsCXXRecordDecl())
     return !RD->isCompleteDefinition() ||
            !RD->hasTrivialDefaultConstructor() ||
            !RD->hasTrivialDestructor();
   return false;
 }
 
-static AttributeList *getMSPropertyAttr(AttributeList *list) {
-  for (AttributeList *it = list; it != nullptr; it = it->getNext())
-    if (it->isDeclspecPropertyAttribute())
-      return it;
+static const AttributeList *
+getMSPropertyAttr(const ParsedAttributesView &list) {
+  ParsedAttributesView::const_iterator Itr =
+      llvm::find_if(list, [](const AttributeList &AL) {
+        return AL.isDeclspecPropertyAttribute();
+      });
+  if (Itr != list.end())
+    return &*Itr;
   return nullptr;
 }
 
 // Check if there is a field shadowing.
 void Sema::CheckShadowInheritedFields(const SourceLocation &Loc,
                                       DeclarationName FieldName,
                                       const CXXRecordDecl *RD) {
   if (Diags.isIgnored(diag::warn_shadow_field, Loc))
if (Loc.isInvalid())
     Loc = D.getLocStart();
 
   Expr *BitWidth = static_cast<Expr*>(BW);
 
   assert(isa<CXXRecordDecl>(CurContext));
   assert(!DS.isFriendSpecified());
 
   bool isFunc = D.isDeclarationOfFunction();
-  AttributeList *MSPropertyAttr =
-      getMSPropertyAttr(D.getDeclSpec().getAttributes().getList());
+  const AttributeList *MSPropertyAttr =
+      getMSPropertyAttr(D.getDeclSpec().getAttributes());
 
   if (cast<CXXRecordDecl>(CurContext)->isInterface()) {
     // The Microsoft extension __interface only permits public member functions
     // and prohibits constructors, destructors, operators, non-public member
     // functions, static methods and data members.
     unsigned InvalidDecl;
     bool ShowDeclName = true;
     if (!isFunc &&
if (SS.isSet() && !SS.isInvalid()) {
         Diag(D.getIdentifierLoc(), diag::err_member_qualification)
           << Name << SS.getRange();
 
       SS.clear();
     }
 
     if (MSPropertyAttr) {
       Member = HandleMSProperty(S, cast<CXXRecordDecl>(CurContext), Loc, D,
-                                BitWidth, InitStyle, AS, MSPropertyAttr);
+                                BitWidth, InitStyle, AS, *MSPropertyAttr);
       if (!Member)
         return nullptr;
       isInstField = false;
     } else {
       Member = HandleField(S, cast<CXXRecordDecl>(CurContext), Loc, D,
                                 BitWidth, InitStyle, AS);
       if (!Member)
         return nullptr;
if (const auto *RT = FT->getBaseElementTypeUnsafe()->getAs<RecordType>())
       if (!RT->isDependentType() &&
           !cast<CXXRecordDecl>(RT->getDecl())->canPassInRegisters()) {
         PrintDiagAndRemoveAttr();
         return;
       }
   }
 }
 
-void Sema::ActOnFinishCXXMemberSpecification(Scope* S, SourceLocation RLoc,
-                                             Decl *TagDecl,
-                                             SourceLocation LBrac,
-                                             SourceLocation RBrac,
-                                             AttributeList *AttrList) {
+void Sema::ActOnFinishCXXMemberSpecification(
+    Scope *S, SourceLocation RLoc, Decl *TagDecl, SourceLocation LBrac,
+    SourceLocation RBrac, const ParsedAttributesView &AttrList) {
   if (!TagDecl)
     return;
 
   AdjustDeclIfTemplate(TagDecl);
 
-  for (const AttributeList* l = AttrList; l; l = l->getNext()) {
-    if (l->getKind() != AttributeList::AT_Visibility)
+  for (const AttributeList &AL : AttrList) {
+    if (AL.getKind() != AttributeList::AT_Visibility)
       continue;
-    l->setInvalid();
-    Diag(l->getLoc(), diag::warn_attribute_after_definition_ignored) <<
-      l->getName();
+    AL.setInvalid();
+    Diag(AL.getLoc(), diag::warn_attribute_after_definition_ignored)
+        << AL.getName();
   }
 
   ActOnFields(S, RLoc, TagDecl, llvm::makeArrayRef(
               // strict aliasing violation!
               reinterpret_cast<Decl**>(FieldCollector->getCurFields()),
               FieldCollector->getCurNumFields()), LBrac, RBrac, AttrList);
 
   CheckCompletedCXXClass(cast<CXXRecordDecl>(TagDecl));
else
     S.Diag(Loc, diag::err_inline_namespace_mismatch);
 
   S.Diag(PrevNS->getLocation(), diag::note_previous_definition);
   *IsInline = PrevNS->isInline();
 }
 
 /// ActOnStartNamespaceDef - This is called at the start of a namespace
 /// definition.
-Decl *Sema::ActOnStartNamespaceDef(Scope *NamespcScope,
-                                   SourceLocation InlineLoc,
-                                   SourceLocation NamespaceLoc,
-                                   SourceLocation IdentLoc,
-                                   IdentifierInfo *II,
-                                   SourceLocation LBrace,
-                                   AttributeList *AttrList,
-                                   UsingDirectiveDecl *&UD) {
+Decl *Sema::ActOnStartNamespaceDef(
+    Scope *NamespcScope, SourceLocation InlineLoc, SourceLocation NamespaceLoc,
+    SourceLocation IdentLoc, IdentifierInfo *II, SourceLocation LBrace,
+    const ParsedAttributesView &AttrList, UsingDirectiveDecl *&UD) {
   SourceLocation StartLoc = InlineLoc.isValid() ? InlineLoc : NamespaceLoc;
   // For anonymous namespace, take the location of the left brace.
   SourceLocation Loc = II ? IdentLoc : LBrace;
   bool IsInline = InlineLoc.isValid();
   bool IsInvalid = false;
   bool IsStd = false;
   bool AddToKnown = false;
   Scope *DeclRegionScope = NamespcScope->getParent();
if (DeclContext *DC = S.computeDeclContext(SS, false)) {
                      S.PDiag(diag::note_namespace_defined_here));
     }
     R.addDecl(Corrected.getFoundDecl());
     return true;
   }
   return false;
 }
 
-Decl *Sema::ActOnUsingDirective(Scope *S,
-                                          SourceLocation UsingLoc,
-                                          SourceLocation NamespcLoc,
-                                          CXXScopeSpec &SS,
-                                          SourceLocation IdentLoc,
-                                          IdentifierInfo *NamespcName,
-                                          AttributeList *AttrList) {
+Decl *Sema::ActOnUsingDirective(Scope *S, SourceLocation UsingLoc,
+                                SourceLocation NamespcLoc, CXXScopeSpec &SS,
+                                const ParsedAttributesView &AttrList) {
   assert(!SS.isInvalid() && "Invalid CXXScopeSpec.");
   assert(NamespcName && "Invalid NamespcName.");
   assert(IdentLoc.isValid() && "Invalid NamespceName location.");
 
   // This can only happen along a recovery path.
   while (S->isTemplateParamScope())
     S = S->getParent();
   assert(S->getFlags() & Scope::DeclScope && "Invalid Scope.");
void Sema::PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir) {
   if (Ctx && !Ctx->isFunctionOrMethod())
     Ctx->addDecl(UDir);
   else
     // Otherwise, it is at block scope. The using-directives will affect lookup
     // only to the end of the scope.
     S->PushUsingDirective(UDir);
 }
 
-
-Decl *Sema::ActOnUsingDeclaration(Scope *S,
-                                  AccessSpecifier AS,
+Decl *Sema::ActOnUsingDeclaration(Scope *S, AccessSpecifier AS,
                                   SourceLocation UsingLoc,
-                                  SourceLocation TypenameLoc,
-                                  CXXScopeSpec &SS,
+                                  SourceLocation TypenameLoc, CXXScopeSpec &SS,
                                   UnqualifiedId &Name,
                                   SourceLocation EllipsisLoc,
-                                  AttributeList *AttrList) {
+                                  const ParsedAttributesView &AttrList) {
   assert(S->getFlags() & Scope::DeclScope && "Invalid Scope.");
 
   if (SS.isEmpty()) {
     Diag(Name.getLocStart(), diag::err_using_requires_qualname);
     return nullptr;
   }
 
   switch (Name.getKind()) {

 };
 } // end anonymous namespace
 
 /// Builds a using declaration.
 ///
 /// \param IsInstantiation - Whether this call arises from an
 ///   instantiation of an unresolved using declaration.  We treat
 ///   the lookup differently for these declarations.
-NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
-                                       SourceLocation UsingLoc,
-                                       bool HasTypenameKeyword,
-                                       SourceLocation TypenameLoc,
-                                       CXXScopeSpec &SS,
-                                       DeclarationNameInfo NameInfo,
-                                       SourceLocation EllipsisLoc,
-                                       AttributeList *AttrList,
-                                       bool IsInstantiation) {
+NamedDecl *Sema::BuildUsingDeclaration(
+    Scope *S, AccessSpecifier AS, SourceLocation UsingLoc,
+    bool HasTypenameKeyword, SourceLocation TypenameLoc, CXXScopeSpec &SS,
+    DeclarationNameInfo NameInfo, SourceLocation EllipsisLoc,
+    const ParsedAttributesView &AttrList, bool IsInstantiation) {
   assert(!SS.isInvalid() && "Invalid CXXScopeSpec.");
   SourceLocation IdentLoc = NameInfo.getLoc();
   assert(IdentLoc.isValid() && "Invalid TargetName location.");
 
   // FIXME: We ignore attributes for now.
 
   // For an inheriting constructor declaration, the name of the using
   // declaration is the name of a constructor in this class, not in the
Diag(SS.getRange().getBegin(),
        diag::err_using_decl_nested_name_specifier_is_not_base_class)
     << SS.getScopeRep()
     << cast<CXXRecordDecl>(CurContext)
     << SS.getRange();
 
   return true;
 }
 
-Decl *Sema::ActOnAliasDeclaration(Scope *S,
-                                  AccessSpecifier AS,
+Decl *Sema::ActOnAliasDeclaration(Scope *S, AccessSpecifier AS,
                                   MultiTemplateParamsArg TemplateParamLists,
-                                  SourceLocation UsingLoc,
-                                  UnqualifiedId &Name,
-                                  AttributeList *AttrList,
-                                  TypeResult Type,
-                                  Decl *DeclFromDeclSpec) {
+                                  SourceLocation UsingLoc, UnqualifiedId &Name,
+                                  const ParsedAttributesView &AttrList,
+                                  TypeResult Type, Decl *DeclFromDeclSpec) {
   // Skip up to the relevant declaration scope.
   while (S->isTemplateParamScope())
     S = S->getParent();
   assert((S->getFlags() & Scope::DeclScope) &&
          "got alias-declaration outside of declaration scope");
 
   if (Type.isInvalid())
     return nullptr;
if (RBraceLoc.isValid()) {
     LinkageSpecDecl* LSDecl = cast<LinkageSpecDecl>(LinkageSpec);
     LSDecl->setRBraceLoc(RBraceLoc);
   }
   PopDeclContext();
   return LinkageSpec;
 }
 
 Decl *Sema::ActOnEmptyDeclaration(Scope *S,
-                                  AttributeList *AttrList,
+                                  const ParsedAttributesView &AttrList,
                                   SourceLocation SemiLoc) {
   Decl *ED = EmptyDecl::Create(Context, CurContext, SemiLoc);
   // Attribute declarations appertain to empty declaration so we handle
   // them here.
-  if (AttrList)
-    ProcessDeclAttributeList(S, ED, AttrList);
 
   CurContext->addDecl(ED);
   return ED;
 }
 
 /// Perform semantic analysis for the variable declaration that
 /// occurs within a C++ catch clause, returning the newly-created
 /// variable.
return FriendDecl::Create(Context, CurContext,
                             TSInfo->getTypeLoc().getLocStart(), TSInfo,
                             FriendLoc);
 }
 
 /// Handle a friend tag declaration where the scope specifier was
 /// templated.
 Decl *Sema::ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                     unsigned TagSpec, SourceLocation TagLoc,
-                                    CXXScopeSpec &SS,
-                                    IdentifierInfo *Name,
+                                    CXXScopeSpec &SS, IdentifierInfo *Name,
                                     SourceLocation NameLoc,
-                                    AttributeList *Attr,
+                                    const ParsedAttributesView &Attr,
                                     MultiTemplateParamsArg TempParamLists) {
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
 
   bool IsMemberSpecialization = false;
   bool Invalid = false;
 
   if (TemplateParameterList *TemplateParams =
           MatchTemplateParametersToScopeSpecifier(
Decl *Sema::ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
   FriendDecl *Friend = FriendDecl::Create(Context, CurContext, NameLoc,
                                           TSI, FriendLoc, TempParamLists);
   Friend->setAccess(AS_public);
   Friend->setUnsupportedFriend(true);
   CurContext->addDecl(Friend);
   return Friend;
 }
 
-
 /// Handle a friend type declaration.  This works in tandem with
 /// ActOnTag.
 ///
 /// Notes on friend class templates:
 ///
 /// We generally treat friend class declarations as if they were
 /// declaring a class.  So, for example, the elaborated type specifier
 /// in a friend declaration is required to obey the restrictions of a
if (Method->isVirtual()) {
     for (const CXXMethodDecl *O : Method->overridden_methods())
       CheckOverridingFunctionExceptionSpec(Method, O);
   }
 }
 
 /// HandleMSProperty - Analyze a __delcspec(property) field of a C++ class.
 ///
 MSPropertyDecl *Sema::HandleMSProperty(Scope *S, RecordDecl *Record,
-                                       SourceLocation DeclStart,
-                                       Declarator &D, Expr *BitWidth,
+                                       SourceLocation DeclStart, Declarator &D,
+                                       Expr *BitWidth,
                                        InClassInitStyle InitStyle,
                                        AccessSpecifier AS,
-                                       AttributeList *MSPropertyAttr) {
+                                       const AttributeList &MSPropertyAttr) {
   IdentifierInfo *II = D.getIdentifier();
   if (!II) {
     Diag(DeclStart, diag::err_anonymous_property);
     return nullptr;
   }
   SourceLocation Loc = D.getIdentifierLoc();
 
   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
if (PrevDecl && PrevDecl->isTemplateParameter()) {
     // Just pretend that we didn't see the previous declaration.
     PrevDecl = nullptr;
   }
 
   if (PrevDecl && !isDeclInScope(PrevDecl, Record, S))
     PrevDecl = nullptr;
 
   SourceLocation TSSL = D.getLocStart();
-  const AttributeList::PropertyData &Data = MSPropertyAttr->getPropertyData();
+  const AttributeList::PropertyData &Data = MSPropertyAttr.getPropertyData();
   MSPropertyDecl *NewPD = MSPropertyDecl::Create(
       Context, Record, Loc, II, T, TInfo, TSSL, Data.GetterId, Data.SetterId);
   ProcessDeclAttributes(TUScope, NewPD, D);
   NewPD->setAccess(AS);
 
   if (NewPD->isInvalidDecl())
     Record->setInvalidDecl();
 

lib/Sema/SemaDeclObjC.cpp

for (unsigned i = 0, n = prevTypeParams->size(); i != n; ++i) {
     // Update the new type parameter's bound to match the previous one.
     newTypeParam->setTypeSourceInfo(
       S.Context.getTrivialTypeSourceInfo(prevTypeParam->getUnderlyingType()));
   }
 
   return false;
 }
 
-Decl *Sema::
-ActOnStartClassInterface(Scope *S, SourceLocation AtInterfaceLoc,
-                         IdentifierInfo *ClassName, SourceLocation ClassLoc,
-                         ObjCTypeParamList *typeParamList,
-                         IdentifierInfo *SuperName, SourceLocation SuperLoc,
-                         ArrayRef<ParsedType> SuperTypeArgs,
-                         SourceRange SuperTypeArgsRange,
-                         Decl * const *ProtoRefs, unsigned NumProtoRefs,
-                         const SourceLocation *ProtoLocs, 
-                         SourceLocation EndProtoLoc, AttributeList *AttrList) {
+Decl *Sema::ActOnStartClassInterface(
+    Scope *S, SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
+    SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
+    ArrayRef<ParsedType> SuperTypeArgs, SourceRange SuperTypeArgsRange,
+    Decl *const *ProtoRefs, unsigned NumProtoRefs,
+    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
+    const ParsedAttributesView &AttrList) {
   assert(ClassName && "Missing class identifier");
 
   // Check for another declaration kind with the same name.
   NamedDecl *PrevDecl =
       LookupSingleName(TUScope, ClassName, ClassLoc, LookupOrdinaryName,
                        forRedeclarationInCurContext());
 
   if (PrevDecl && !isa<ObjCInterfaceDecl>(PrevDecl)) {
if (PrevIDecl) {
     // Class already seen. Was it a definition?
     if (ObjCInterfaceDecl *Def = PrevIDecl->getDefinition()) {
       Diag(AtInterfaceLoc, diag::err_duplicate_class_def)
         << PrevIDecl->getDeclName();
       Diag(Def->getLocation(), diag::note_previous_definition);
       IDecl->setInvalidDecl();
     }
   }
-  
-  if (AttrList)
-    ProcessDeclAttributeList(TUScope, IDecl, AttrList);
   AddPragmaAttributes(TUScope, IDecl);
   PushOnScopeChains(IDecl, TUScope);
 
   // Start the definition of this class. If we're in a redefinition case, there 
   // may already be a definition, so we'll end up adding to it.
   if (!IDecl->hasDefinition())
     IDecl->startDefinition();
   
if (ObjCProtocolDecl *PDecl = LookupProtocol((*I)->getIdentifier(),
       if (CheckForwardProtocolDeclarationForCircularDependency(PName, Ploc,
             PDecl->getLocation(), PDecl->getReferencedProtocols()))
         res = true;
     }
   }
   return res;
 }
 
-Decl *
-Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
-                                  IdentifierInfo *ProtocolName,
-                                  SourceLocation ProtocolLoc,
-                                  Decl * const *ProtoRefs,
-                                  unsigned NumProtoRefs,
-                                  const SourceLocation *ProtoLocs,
-                                  SourceLocation EndProtoLoc,
-                                  AttributeList *AttrList) {
+Decl *Sema::ActOnStartProtocolInterface(
+    SourceLocation AtProtoInterfaceLoc, IdentifierInfo *ProtocolName,
+    SourceLocation ProtocolLoc, Decl *const *ProtoRefs, unsigned NumProtoRefs,
+    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
+    const ParsedAttributesView &AttrList) {
   bool err = false;
   // FIXME: Deal with AttrList.
   assert(ProtocolName && "Missing protocol identifier");
   ObjCProtocolDecl *PrevDecl = LookupProtocol(ProtocolName, ProtocolLoc,
                                               forRedeclarationInCurContext());
   ObjCProtocolDecl *PDecl = nullptr;
   if (ObjCProtocolDecl *Def = PrevDecl? PrevDecl->getDefinition() : nullptr) {
     // If we already have a definition, complain.
if (ObjCProtocolDecl *Def = PrevDecl? PrevDecl->getDefinition() : nullptr) {
     // Create the new declaration.
     PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
                                      ProtocolLoc, AtProtoInterfaceLoc,
                                      /*PrevDecl=*/PrevDecl);
     
     PushOnScopeChains(PDecl, TUScope);
     PDecl->startDefinition();
   }
-  
-  if (AttrList)
-    ProcessDeclAttributeList(TUScope, PDecl, AttrList);
   AddPragmaAttributes(TUScope, PDecl);
 
   // Merge attributes from previous declarations.
   if (PrevDecl)
     mergeDeclAttributes(PDecl, PrevDecl);
 
   if (!err && NumProtoRefs ) {
     /// Check then save referenced protocols.
auto resolveTypeReference = [&](TypeOrClassDecl typeDecl, SourceLocation loc)
 
     // Form the declarator.
     Declarator D(DS, DeclaratorContext::TypeNameContext);
 
     // If we have a typedef of an Objective-C class type that is missing a '*',
     // add the '*'.
     if (type->getAs<ObjCInterfaceType>()) {
       SourceLocation starLoc = getLocForEndOfToken(loc);
-      ParsedAttributes parsedAttrs(attrFactory);
       D.AddTypeInfo(DeclaratorChunk::getPointer(/*typeQuals=*/0, starLoc,
                                                 SourceLocation(),
                                                 SourceLocation(),
                                                 SourceLocation(),
                                                 SourceLocation(),
                                                 SourceLocation()),
-                                                parsedAttrs,
                                                 starLoc);
 
       // Diagnose the missing '*'.
       Diag(loc, diag::err_objc_type_arg_missing_star)
         << type
         << FixItHint::CreateInsertion(starLoc, " *");
     }
 
for (const auto *Method : CAT->methods()) {
     }
   }
 }
 
 /// ActOnForwardProtocolDeclaration - Handle \@protocol foo;
 Sema::DeclGroupPtrTy
 Sema::ActOnForwardProtocolDeclaration(SourceLocation AtProtocolLoc,
                                       ArrayRef<IdentifierLocPair> IdentList,
-                                      AttributeList *attrList) {
+                                      const ParsedAttributesView &attrList) {
   SmallVector<Decl *, 8> DeclsInGroup;
   for (const IdentifierLocPair &IdentPair : IdentList) {
     IdentifierInfo *Ident = IdentPair.first;
     ObjCProtocolDecl *PrevDecl = LookupProtocol(Ident, IdentPair.second,
                                                 forRedeclarationInCurContext());
     ObjCProtocolDecl *PDecl
       = ObjCProtocolDecl::Create(Context, CurContext, Ident, 
                                  IdentPair.second, AtProtocolLoc,
                                  PrevDecl);
         
     PushOnScopeChains(PDecl, TUScope);
     CheckObjCDeclScope(PDecl);
-    
-    if (attrList)
-      ProcessDeclAttributeList(TUScope, PDecl, attrList);
     AddPragmaAttributes(TUScope, PDecl);
 
     if (PrevDecl)
       mergeDeclAttributes(PDecl, PrevDecl);
 
     DeclsInGroup.push_back(PDecl);
   }
 
   return BuildDeclaratorGroup(DeclsInGroup);
 }
 
-Decl *Sema::
-ActOnStartCategoryInterface(SourceLocation AtInterfaceLoc,
-                            IdentifierInfo *ClassName, SourceLocation ClassLoc,
-                            ObjCTypeParamList *typeParamList,
-                            IdentifierInfo *CategoryName,
-                            SourceLocation CategoryLoc,
-                            Decl * const *ProtoRefs,
-                            unsigned NumProtoRefs,
-                            const SourceLocation *ProtoLocs,
-                            SourceLocation EndProtoLoc,
-                            AttributeList *AttrList) {
+Decl *Sema::ActOnStartCategoryInterface(
+    SourceLocation AtInterfaceLoc, IdentifierInfo *ClassName,
+    SourceLocation ClassLoc, ObjCTypeParamList *typeParamList,
+    IdentifierInfo *CategoryName, SourceLocation CategoryLoc,
+    Decl *const *ProtoRefs, unsigned NumProtoRefs,
+    const SourceLocation *ProtoLocs, SourceLocation EndProtoLoc,
+    const ParsedAttributesView &AttrList) {
   ObjCCategoryDecl *CDecl;
   ObjCInterfaceDecl *IDecl = getObjCInterfaceDecl(ClassName, ClassLoc, true);
 
   /// Check that class of this category is already completely declared.
 
   if (!IDecl 
       || RequireCompleteType(ClassLoc, Context.getObjCInterfaceType(IDecl),
                              diag::err_category_forward_interface,
CDecl = ObjCCategoryDecl::Create(Context, CurContext, AtInterfaceLoc,
                                    ClassLoc, CategoryLoc, CategoryName, IDecl,
                                    typeParamList);
   // FIXME: PushOnScopeChains?
   CurContext->addDecl(CDecl);
 
   // Process the attributes before looking at protocols to ensure that the
   // availability attribute is attached to the category to provide availability
   // checking for protocol uses.
-  if (AttrList)
-    ProcessDeclAttributeList(TUScope, CDecl, AttrList);
   AddPragmaAttributes(TUScope, CDecl);
 
   if (NumProtoRefs) {
     diagnoseUseOfProtocols(*this, CDecl, (ObjCProtocolDecl*const*)ProtoRefs,
                            NumProtoRefs, ProtoLocs);
     CDecl->setProtocolList((ObjCProtocolDecl*const*)ProtoRefs, NumProtoRefs,
                            ProtoLocs, Context);
     // Protocols in the class extension belong to the class.
if (SemaRef.getASTContext().getTargetInfo().getPlatformMinVersion() >=
     return;
   SemaRef.Diag(Loc, diag::err_objc_method_unsupported_param_ret_type)
       << T << (Method->getReturnType()->isVectorType() ? /*return value*/ 1
                                                        : /*parameter*/ 0)
       << (Triple.isMacOSX() ? "macOS 10.11" : "iOS 9");
 }
 
 Decl *Sema::ActOnMethodDeclaration(
-    Scope *S,
-    SourceLocation MethodLoc, SourceLocation EndLoc,
-    tok::TokenKind MethodType, 
-    ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
-    ArrayRef<SourceLocation> SelectorLocs,
-    Selector Sel,
+    Scope *S, SourceLocation MethodLoc, SourceLocation EndLoc,
+    tok::TokenKind MethodType, ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
+    ArrayRef<SourceLocation> SelectorLocs, Selector Sel,
     // optional arguments. The number of types/arguments is obtained
     // from the Sel.getNumArgs().
-    ObjCArgInfo *ArgInfo,
-    DeclaratorChunk::ParamInfo *CParamInfo, unsigned CNumArgs, // c-style args
-    AttributeList *AttrList, tok::ObjCKeywordKind MethodDeclKind,
+    ObjCArgInfo *ArgInfo, DeclaratorChunk::ParamInfo *CParamInfo,
+    unsigned CNumArgs, // c-style args
+    const ParsedAttributesView &AttrList, tok::ObjCKeywordKind MethodDeclKind,
     bool isVariadic, bool MethodDefinition) {
   // Make sure we can establish a context for the method.
   if (!CurContext->isObjCContainer()) {
     Diag(MethodLoc, diag::err_missing_method_context);
     return nullptr;
   }
   Decl *ClassDecl = cast<ObjCContainerDecl>(CurContext);
   QualType resultDeclType;
for (unsigned i = 0, e = CNumArgs; i != e; ++i) {
     Param->setDeclContext(ObjCMethod);
     Params.push_back(Param);
   }
   
   ObjCMethod->setMethodParams(Context, Params, SelectorLocs);
   ObjCMethod->setObjCDeclQualifier(
     CvtQTToAstBitMask(ReturnQT.getObjCDeclQualifier()));
 
-  if (AttrList)
-    ProcessDeclAttributeList(TUScope, ObjCMethod, AttrList);
   AddPragmaAttributes(TUScope, ObjCMethod);
 
   // Add the method now.
   const ObjCMethodDecl *PrevMethod = nullptr;
   if (ObjCImplDecl *ImpDecl = dyn_cast<ObjCImplDecl>(ClassDecl)) {
     if (MethodType == tok::minus) {
       PrevMethod = ImpDecl->getInstanceMethod(Sel);
       ImpDecl->addInstanceMethod(ObjCMethod);

lib/Sema/SemaLambda.cpp

void Sema::ActOnLambdaError(SourceLocation StartLoc, Scope *CurScope,
   if (!IsInstantiation)
     PopDeclContext();
 
   // Finalize the lambda.
   CXXRecordDecl *Class = LSI->Lambda;
   Class->setInvalidDecl();
   SmallVector<Decl*, 4> Fields(Class->fields());
   ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
-              SourceLocation(), nullptr);
+              SourceLocation(), ParsedAttributesView());
   CheckCompletedCXXClass(Class);
 
   PopFunctionScopeInfo();
 }
 
 QualType Sema::getLambdaConversionFunctionResultType(
     const FunctionProtoType *CallOpProto) {
   // The function type inside the pointer type is the same as the call
bool IsGenericLambda;
     //   operator.
     // FIXME: Fix generic lambda to block conversions.
     if (getLangOpts().Blocks && getLangOpts().ObjC1 && !IsGenericLambda)
       addBlockPointerConversion(*this, IntroducerRange, Class, CallOperator);
     
     // Finalize the lambda class.
     SmallVector<Decl*, 4> Fields(Class->fields());
     ActOnFields(nullptr, Class->getLocation(), Class, Fields, SourceLocation(),
-                SourceLocation(), nullptr);
+                SourceLocation(), ParsedAttributesView());
     CheckCompletedCXXClass(Class);
   }
 
   Cleanup.mergeFrom(LambdaCleanup);
 
   LambdaExpr *Lambda = LambdaExpr::Create(Context, Class, IntroducerRange, 
                                           CaptureDefault, CaptureDefaultLoc,
                                           Captures, 

lib/Sema/SemaStmt.cpp

void Sema::ActOnCapturedRegionError() {
   PopExpressionEvaluationContext();
 
   CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
   RecordDecl *Record = RSI->TheRecordDecl;
   Record->setInvalidDecl();
 
   SmallVector<Decl*, 4> Fields(Record->fields());
   ActOnFields(/*Scope=*/nullptr, Record->getLocation(), Record, Fields,
-              SourceLocation(), SourceLocation(), /*AttributeList=*/nullptr);
+              SourceLocation(), SourceLocation(), ParsedAttributesView());
 
   PopDeclContext();
   PopFunctionScopeInfo();
 }
 
 StmtResult Sema::ActOnCapturedRegionEnd(Stmt *S) {
   CapturedRegionScopeInfo *RSI = getCurCapturedRegion();
 

lib/Sema/SemaStmtAttr.cpp

default:
     // if we're here, then we parsed a known attribute, but didn't recognize
     // it as a statement attribute => it is declaration attribute
     S.Diag(A.getRange().getBegin(), diag::err_decl_attribute_invalid_on_stmt)
         << A.getName() << St->getLocStart();
     return nullptr;
   }
 }
 
-StmtResult Sema::ProcessStmtAttributes(Stmt *S, AttributeList *AttrList,
+StmtResult Sema::ProcessStmtAttributes(Stmt *S,
+                                       const ParsedAttributesView &AttrList,
                                        SourceRange Range) {
   SmallVector<const Attr*, 8> Attrs;
-  for (const AttributeList* l = AttrList; l; l = l->getNext()) {
-    if (Attr *a = ProcessStmtAttribute(*this, S, *l, Range))
+  for (const AttributeList &AL : AttrList) {
+    if (Attr *a = ProcessStmtAttribute(*this, S, AL, Range))
       Attrs.push_back(a);
   }
 
   CheckForIncompatibleAttributes(*this, Attrs);
 
   if (Attrs.empty())
     return S;
 
   return ActOnAttributedStmt(Range.getBegin(), Attrs, S);
 }

lib/Sema/SemaTemplate.cpp

return TemplateParameterList::Create(
       RAngleLoc, RequiresClause);
 }
 
 static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
   if (SS.isSet())
     T->setQualifierInfo(SS.getWithLocInContext(T->getASTContext()));
 }
 
-DeclResult
-Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
-                         SourceLocation KWLoc, CXXScopeSpec &SS,
-                         IdentifierInfo *Name, SourceLocation NameLoc,
-                         AttributeList *Attr,
-                         TemplateParameterList *TemplateParams,
-                         AccessSpecifier AS, SourceLocation ModulePrivateLoc,
-                         SourceLocation FriendLoc,
-                         unsigned NumOuterTemplateParamLists,
-                         TemplateParameterList** OuterTemplateParamLists,
-                         SkipBodyInfo *SkipBody) {
+DeclResult Sema::CheckClassTemplate(
+    Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
+    CXXScopeSpec &SS, IdentifierInfo *Name, SourceLocation NameLoc,
+    const ParsedAttributesView &Attr, TemplateParameterList *TemplateParams,
+    SourceLocation FriendLoc, unsigned NumOuterTemplateParamLists,
+    TemplateParameterList **OuterTemplateParamLists, SkipBodyInfo *SkipBody) {
   assert(TemplateParams && TemplateParams->size() > 0 &&
          "No template parameters");
   assert(TUK != TUK_Reference && "Can only declare or define class templates");
   bool Invalid = false;
 
   // Check that we can declare a template here.
   if (CheckTemplateDeclScope(S, TemplateParams))
     return true;
DeclResult Sema::CheckClassTemplate(
 
   // Set the lexical context of these templates
   NewClass->setLexicalDeclContext(CurContext);
   NewTemplate->setLexicalDeclContext(CurContext);
 
   if (TUK == TUK_Definition)
     NewClass->startDefinition();
 
-  if (Attr)
-    ProcessDeclAttributeList(S, NewClass, Attr);
 
   if (PrevClassTemplate)
     mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
 
   AddPushedVisibilityAttribute(NewClass);
 
   if (TUK != TUK_Friend) {
     // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
if (CheckNonTypeTemplatePartialSpecializationArgs(*this, TemplateNameLoc,
                                                       Param, &TemplateArgs[I],
                                                       1, I >= NumExplicit))
       return true;
   }
 
   return false;
 }
 
-DeclResult
-Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
-                                       TagUseKind TUK,
-                                       SourceLocation KWLoc,
-                                       SourceLocation ModulePrivateLoc,
-                                       TemplateIdAnnotation &TemplateId,
-                                       AttributeList *Attr,
-                                       MultiTemplateParamsArg
-                                           TemplateParameterLists,
-                                       SkipBodyInfo *SkipBody) {
+DeclResult Sema::ActOnClassTemplateSpecialization(
+    Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
+    SourceLocation ModulePrivateLoc, TemplateIdAnnotation &TemplateId,
+    const ParsedAttributesView &Attr,
+    MultiTemplateParamsArg TemplateParameterLists, SkipBodyInfo *SkipBody) {
   assert(TUK != TUK_Reference && "References are not specializations");
 
   CXXScopeSpec &SS = TemplateId.SS;
 
   // NOTE: KWLoc is the location of the tag keyword. This will instead
   // store the location of the outermost template keyword in the declaration.
   SourceLocation TemplateKWLoc = TemplateParameterLists.size() > 0
     ? TemplateParameterLists[0]->getTemplateLoc() : KWLoc;
if (Def && SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
       SourceRange Range(TemplateNameLoc, RAngleLoc);
       Diag(TemplateNameLoc, diag::err_redefinition) << Specialization << Range;
       Diag(Def->getLocation(), diag::note_previous_definition);
       Specialization->setInvalidDecl();
       return true;
     }
   }
 
-  if (Attr)
-    ProcessDeclAttributeList(S, Specialization, Attr);
 
   // Add alignment attributes if necessary; these attributes are checked when
   // the ASTContext lays out the structure.
   if (TUK == TUK_Definition) {
     AddAlignmentAttributesForRecord(Specialization);
     AddMsStructLayoutForRecord(Specialization);
   }
 
if (auto *BT = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
             B.getType()->getAsCXXRecordDecl()))
       S.propagateDLLAttrToBaseClassTemplate(Def, A, BT, B.getLocStart());
   }
 
   S.referenceDLLExportedClassMethods();
 }
 
 // Explicit instantiation of a class template specialization
-DeclResult
-Sema::ActOnExplicitInstantiation(Scope *S,
-                                 SourceLocation ExternLoc,
-                                 SourceLocation TemplateLoc,
-                                 unsigned TagSpec,
-                                 SourceLocation KWLoc,
-                                 const CXXScopeSpec &SS,
-                                 TemplateTy TemplateD,
-                                 SourceLocation TemplateNameLoc,
-                                 SourceLocation LAngleLoc,
-                                 ASTTemplateArgsPtr TemplateArgsIn,
-                                 SourceLocation RAngleLoc,
-                                 AttributeList *Attr) {
+DeclResult Sema::ActOnExplicitInstantiation(
+    Scope *S, SourceLocation ExternLoc, SourceLocation TemplateLoc,
+    unsigned TagSpec, SourceLocation KWLoc, const CXXScopeSpec &SS,
+    TemplateTy TemplateD, SourceLocation TemplateNameLoc,
+    SourceLocation LAngleLoc, ASTTemplateArgsPtr TemplateArgsIn,
+    SourceLocation RAngleLoc, const ParsedAttributesView &Attr) {
   // Find the class template we're specializing
   TemplateName Name = TemplateD.get();
   TemplateDecl *TD = Name.getAsTemplateDecl();
   // Check that the specialization uses the same tag kind as the
   // original template.
   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
   assert(Kind != TTK_Enum &&
          "Invalid enum tag in class template explicit instantiation!");
DeclResult Sema::ActOnExplicitInstantiation(
   //   definition and an explicit instantiation declaration. An explicit
   //   instantiation declaration begins with the extern keyword. [...]
   TemplateSpecializationKind TSK = ExternLoc.isInvalid()
                                        ? TSK_ExplicitInstantiationDefinition
                                        : TSK_ExplicitInstantiationDeclaration;
 
   if (TSK == TSK_ExplicitInstantiationDeclaration) {
     // Check for dllexport class template instantiation declarations.
-    for (AttributeList *A = Attr; A; A = A->getNext()) {
-      if (A->getKind() == AttributeList::AT_DLLExport) {
+    for (const AttributeList &AL : Attr) {
+      if (AL.getKind() == AttributeList::AT_DLLExport) {
         Diag(ExternLoc,
              diag::warn_attribute_dllexport_explicit_instantiation_decl);
-        Diag(A->getLoc(), diag::note_attribute);
+        Diag(AL.getLoc(), diag::note_attribute);
         break;
       }
     }
 
     if (auto *A = ClassTemplate->getTemplatedDecl()->getAttr<DLLExportAttr>()) {
       Diag(ExternLoc,
            diag::warn_attribute_dllexport_explicit_instantiation_decl);
       Diag(A->getLocation(), diag::note_attribute);
     }
   }
 
   // In MSVC mode, dllimported explicit instantiation definitions are treated as
   // instantiation declarations for most purposes.
   bool DLLImportExplicitInstantiationDef = false;
   if (TSK == TSK_ExplicitInstantiationDefinition &&
       Context.getTargetInfo().getCXXABI().isMicrosoft()) {
     // Check for dllimport class template instantiation definitions.
     bool DLLImport =
         ClassTemplate->getTemplatedDecl()->getAttr<DLLImportAttr>();
-    for (AttributeList *A = Attr; A; A = A->getNext()) {
-      if (A->getKind() == AttributeList::AT_DLLImport)
+    for (const AttributeList &AL : Attr) {
+      if (AL.getKind() == AttributeList::AT_DLLImport)
         DLLImport = true;
-      if (A->getKind() == AttributeList::AT_DLLExport) {
+      if (AL.getKind() == AttributeList::AT_DLLExport) {
         // dllexport trumps dllimport here.
         DLLImport = false;
         break;
       }
     }
     if (DLLImport) {
       TSK = TSK_ExplicitInstantiationDeclaration;
       DLLImportExplicitInstantiationDef = true;
DeclResult Sema::ActOnExplicitInstantiation(
   Specialization->setTypeAsWritten(WrittenTy);
 
   // Set source locations for keywords.
   Specialization->setExternLoc(ExternLoc);
   Specialization->setTemplateKeywordLoc(TemplateLoc);
   Specialization->setBraceRange(SourceRange());
 
   bool PreviouslyDLLExported = Specialization->hasAttr<DLLExportAttr>();
-  if (Attr)
-    ProcessDeclAttributeList(S, Specialization, Attr);
 
   // Add the explicit instantiation into its lexical context. However,
   // since explicit instantiations are never found by name lookup, we
   // just put it into the declaration context directly.
   Specialization->setLexicalDeclContext(CurContext);
   CurContext->addDecl(Specialization);
 
   // Syntax is now OK, so return if it has no other effect on semantics.
if (Def) {
     Specialization->setTemplateSpecializationKind(TSK);
   }
 
   return Specialization;
 }
 
 // Explicit instantiation of a member class of a class template.
 DeclResult
-Sema::ActOnExplicitInstantiation(Scope *S,
-                                 SourceLocation ExternLoc,
-                                 SourceLocation TemplateLoc,
-                                 unsigned TagSpec,
-                                 SourceLocation KWLoc,
-                                 CXXScopeSpec &SS,
-                                 IdentifierInfo *Name,
-                                 SourceLocation NameLoc,
-                                 AttributeList *Attr) {
+Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation ExternLoc,
+                                 SourceLocation TemplateLoc, unsigned TagSpec,
+                                 SourceLocation KWLoc, CXXScopeSpec &SS,
+                                 IdentifierInfo *Name, SourceLocation NameLoc,
+                                 const ParsedAttributesView &Attr) {
 
   bool Owned = false;
   bool IsDependent = false;
   Decl *TagD = ActOnTag(S, TagSpec, Sema::TUK_Reference,
                         KWLoc, SS, Name, NameLoc, Attr, AS_none,
                         /*ModulePrivateLoc=*/SourceLocation(),
                         MultiTemplateParamsArg(), Owned, IsDependent,
                         SourceLocation(), false, TypeResult(),
if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK, Prev,
                                                PrevTSK, POI, HasNoEffect))
       return true;
 
     if (!HasNoEffect) {
       // Instantiate static data member or variable template.
       Prev->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
       if (PrevTemplate) {
         // Merge attributes.
-        if (AttributeList *Attr = D.getDeclSpec().getAttributes().getList())
-          ProcessDeclAttributeList(S, Prev, Attr);
+        ProcessDeclAttributeList(S, Prev, D.getDeclSpec().getAttributes());
       }
       if (TSK == TSK_ExplicitInstantiationDefinition)
         InstantiateVariableDefinition(D.getIdentifierLoc(), Prev);
     }
 
     // Check the new variable specialization against the parsed input.
     if (PrevTemplate && Prev && !Context.hasSameType(Prev->getType(), R)) {
       Diag(T->getTypeLoc().getLocStart(),
DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
 
   // C++ [temp.explicit]p1:
   //   A [...] function [...] can be explicitly instantiated from its template.
   //   A member function [...] of a class template can be explicitly
   //  instantiated from the member definition associated with its class
   //  template.
   UnresolvedSet<8> TemplateMatches;
   FunctionDecl *NonTemplateMatch = nullptr;
-  AttributeList *Attr = D.getDeclSpec().getAttributes().getList();
   TemplateSpecCandidateSet FailedCandidates(D.getIdentifierLoc());
   for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
        P != PEnd; ++P) {
     NamedDecl *Prev = *P;
     if (!HasExplicitTemplateArgs) {
       if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Prev)) {
         QualType Adjusted = adjustCCAndNoReturn(R, Method->getType(),
                                                 /*AdjustExceptionSpec*/true);
for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
     // Target attributes are part of the cuda function signature, so
     // the cuda target of the instantiated function must match that of its
     // template.  Given that C++ template deduction does not take
     // target attributes into account, we reject candidates here that
     // have a different target.
     if (LangOpts.CUDA &&
         IdentifyCUDATarget(Specialization,
                            /* IgnoreImplicitHDAttributes = */ true) !=
-            IdentifyCUDATarget(Attr)) {
+            IdentifyCUDATarget(D.getDeclSpec().getAttributes())) {
       FailedCandidates.addCandidate().set(
           P.getPair(), FunTmpl->getTemplatedDecl(),
           MakeDeductionFailureInfo(Context, TDK_CUDATargetMismatch, Info));
       continue;
     }
 
     TemplateMatches.addDecl(Specialization, P.getAccess());
   }
if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK,
       return true;
 
     // FIXME: We may still want to build some representation of this
     // explicit specialization.
     if (HasNoEffect)
       return (Decl*) nullptr;
   }
 
-  if (Attr)
-    ProcessDeclAttributeList(S, Specialization, Attr);
+  ProcessDeclAttributeList(S, Specialization, D.getDeclSpec().getAttributes());
 
   // In MSVC mode, dllimported explicit instantiation definitions are treated as
   // instantiation declarations.
   if (TSK == TSK_ExplicitInstantiationDefinition &&
       Specialization->hasAttr<DLLImportAttr>() &&
       Context.getTargetInfo().getCXXABI().isMicrosoft())
     TSK = TSK_ExplicitInstantiationDeclaration;
 

lib/Sema/SemaTemplateInstantiate.cpp

if (NewMember) {
       // instantiations was a semantic disaster, and we'll want to mark the
       // declaration invalid.
       // For now, we expect to skip some members that we can't yet handle.
     }
   }
 
   // Finish checking fields.
   ActOnFields(nullptr, Instantiation->getLocation(), Instantiation, Fields,
-              SourceLocation(), SourceLocation(), nullptr);
+              SourceLocation(), SourceLocation(), ParsedAttributesView());
   CheckCompletedCXXClass(Instantiation);
 
   // Default arguments are parsed, if not instantiated. We can go instantiate
   // default arg exprs for default constructors if necessary now.
   ActOnFinishCXXNonNestedClass(Instantiation);
 
   // Instantiate late parsed attributes, and attach them to their decls.
   // See Sema::InstantiateAttrs

lib/Sema/SemaTemplateInstantiateDecl.cpp

if (EnumConst) {
         // If the enumeration is within a function or method, record the enum
         // constant as a local.
         SemaRef.CurrentInstantiationScope->InstantiatedLocal(EC, EnumConst);
       }
     }
   }
 
   SemaRef.ActOnEnumBody(Enum->getLocation(), Enum->getBraceRange(), Enum,
-                        Enumerators,
-                        nullptr, nullptr);
+                        Enumerators, nullptr, ParsedAttributesView());
 }
 
 Decl *TemplateDeclInstantiator::VisitEnumConstantDecl(EnumConstantDecl *D) {
   llvm_unreachable("EnumConstantDecls can only occur within EnumDecls.");
 }
 
 Decl *
 TemplateDeclInstantiator::VisitBuiltinTemplateDecl(BuiltinTemplateDecl *D) {
Decl *TemplateDeclInstantiator::instantiateUnresolvedUsingDecl(
   // slice of a pack expansion.
   bool InstantiatingSlice = D->getEllipsisLoc().isValid() &&
                             SemaRef.ArgumentPackSubstitutionIndex != -1;
   SourceLocation EllipsisLoc =
       InstantiatingSlice ? SourceLocation() : D->getEllipsisLoc();
 
   NamedDecl *UD = SemaRef.BuildUsingDeclaration(
       /*Scope*/ nullptr, D->getAccess(), D->getUsingLoc(),
-      /*HasTypename*/ TD, TypenameLoc, SS, NameInfo, EllipsisLoc, nullptr,
+      /*HasTypename*/ TD, TypenameLoc, SS, NameInfo, EllipsisLoc,
+      ParsedAttributesView(),
       /*IsInstantiation*/ true);
   if (UD)
     SemaRef.Context.setInstantiatedFromUsingDecl(UD, D);
 
   return UD;
 }
 
 Decl *TemplateDeclInstantiator::VisitUnresolvedUsingTypenameDecl(

lib/Sema/SemaType.cpp

unsigned getCurrentChunkIndex() const {
       return chunkIndex;
     }
 
     void setCurrentChunkIndex(unsigned idx) {
       assert(idx <= declarator.getNumTypeObjects());
       chunkIndex = idx;
     }
 
-    AttributeList *&getCurrentAttrListRef() const {
+    ParsedAttributesView &getCurrentAttributes() const {
       if (isProcessingDeclSpec())
-        return getMutableDeclSpec().getAttributes().getListRef();
-      return declarator.getTypeObject(chunkIndex).getAttrListRef();
+        return getMutableDeclSpec().getAttributes();
+      return declarator.getTypeObject(chunkIndex).getAttrs();
     }
 
     /// Save the current set of attributes on the DeclSpec.
     void saveDeclSpecAttrs() {
       // Don't try to save them multiple times.
       if (hasSavedAttrs) return;
 
       DeclSpec &spec = getMutableDeclSpec();
-      for (AttributeList *attr = spec.getAttributes().getList(); attr;
-             attr = attr->getNext())
-        savedAttrs.push_back(attr);
+      for (AttributeList &AL : spec.getAttributes())
+        savedAttrs.push_back(&AL);
       trivial &= savedAttrs.empty();
       hasSavedAttrs = true;
     }
 
     /// Record that we had nowhere to put the given type attribute.
     /// We will diagnose such attributes later.
     void addIgnoredTypeAttr(AttributeList &attr) {
       ignoredTypeAttrs.push_back(&attr);
namespace {
   private:
     DeclSpec &getMutableDeclSpec() const {
       return const_cast<DeclSpec&>(declarator.getDeclSpec());
     }
 
     void restoreDeclSpecAttrs() {
       assert(hasSavedAttrs);
 
-      if (savedAttrs.empty()) {
-        getMutableDeclSpec().getAttributes().set(nullptr);
-        return;
-      }
-
-      getMutableDeclSpec().getAttributes().set(savedAttrs[0]);
-      for (unsigned i = 0, e = savedAttrs.size() - 1; i != e; ++i)
-        savedAttrs[i]->setNext(savedAttrs[i+1]);
-      savedAttrs.back()->setNext(nullptr);
+      getMutableDeclSpec().getAttributes().clearListOnly();
+      for (AttributeList *AL : savedAttrs)
+        getMutableDeclSpec().getAttributes().addAtStart(AL);
     }
   };
 } // end anonymous namespace
 
-static void spliceAttrIntoList(AttributeList &attr, AttributeList *&head) {
-  attr.setNext(head);
-  head = &attr;
-}
-
-static void spliceAttrOutOfList(AttributeList &attr, AttributeList *&head) {
-  if (head == &attr) {
-    head = attr.getNext();
-    return;
-  }
-
-  AttributeList *cur = head;
-  while (true) {
-    assert(cur && cur->getNext() && "ran out of attrs?");
-    if (cur->getNext() == &attr) {
-      cur->setNext(attr.getNext());
-      return;
-    }
-    cur = cur->getNext();
-  }
-}
-
 static void moveAttrFromListToList(AttributeList &attr,
-                                   AttributeList *&fromList,
-                                   AttributeList *&toList) {
-  spliceAttrOutOfList(attr, fromList);
-  spliceAttrIntoList(attr, toList);
+                                   ParsedAttributesView &fromList,
+                                   ParsedAttributesView &toList) {
+  fromList.remove(&attr);
+  toList.addAtStart(&attr);
 }
 
 /// The location of a type attribute.
 enum TypeAttrLocation {
   /// The attribute is in the decl-specifier-seq.
   TAL_DeclSpec,
   /// The attribute is part of a DeclaratorChunk.
   TAL_DeclChunk,
   /// The attribute is immediately after the declaration's name.
   TAL_DeclName
 };
 
-static void processTypeAttrs(TypeProcessingState &state,
-                             QualType &type, TypeAttrLocation TAL,
-                             AttributeList *attrs);
+static void processTypeAttrs(TypeProcessingState &state, QualType &type,
+                             TypeAttrLocation TAL, ParsedAttributesView &attrs);
 
 static bool handleFunctionTypeAttr(TypeProcessingState &state,
                                    AttributeList &attr,
                                    QualType &type);
 
 static bool handleMSPointerTypeQualifierAttr(TypeProcessingState &state,
                                              AttributeList &attr,
                                              QualType &type);
case DeclaratorChunk::BlockPointer: {
       // of a block.
       DeclaratorChunk *destChunk = nullptr;
       if (state.isProcessingDeclSpec() &&
           attr.getKind() == AttributeList::AT_ObjCOwnership)
         destChunk = maybeMovePastReturnType(declarator, i - 1,
                                             /*onlyBlockPointers=*/true);
       if (!destChunk) destChunk = &chunk;
 
-      moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
-                             destChunk->getAttrListRef());
+      moveAttrFromListToList(attr, state.getCurrentAttributes(),
+                             destChunk->getAttrs());
       return;
     }
 
     case DeclaratorChunk::Paren:
     case DeclaratorChunk::Array:
       continue;
 
     // We may be starting at the return type of a block.
     case DeclaratorChunk::Function:
       if (state.isProcessingDeclSpec() &&
           attr.getKind() == AttributeList::AT_ObjCOwnership) {
         if (DeclaratorChunk *dest = maybeMovePastReturnType(
                                       declarator, i,
                                       /*onlyBlockPointers=*/true)) {
-          moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
-                                 dest->getAttrListRef());
+          moveAttrFromListToList(attr, state.getCurrentAttributes(),
+                                 dest->getAttrs());
           return;
         }
       }
       goto error;
 
     // Don't walk through these.
     case DeclaratorChunk::Reference:
     case DeclaratorChunk::MemberPointer:
done:
   // That might actually be the decl spec if we weren't blocked by
   // anything in the declarator.
   if (considerDeclSpec) {
     if (handleObjCPointerTypeAttr(state, attr, declSpecType)) {
       // Splice the attribute into the decl spec.  Prevents the
       // attribute from being applied multiple times and gives
       // the source-location-filler something to work with.
       state.saveDeclSpecAttrs();
-      moveAttrFromListToList(attr, declarator.getAttrListRef(),
-               declarator.getMutableDeclSpec().getAttributes().getListRef());
+      moveAttrFromListToList(attr, declarator.getAttributes(),
+                             declarator.getMutableDeclSpec().getAttributes());
       return;
     }
   }
 
   // Otherwise, if we found an appropriate chunk, splice the attribute
   // into it.
   if (innermost != -1U) {
-    moveAttrFromListToList(attr, declarator.getAttrListRef(),
-                       declarator.getTypeObject(innermost).getAttrListRef());
+    moveAttrFromListToList(attr, declarator.getAttributes(),
+                           declarator.getTypeObject(innermost).getAttrs());
     return;
   }
 
   // Otherwise, diagnose when we're done building the type.
-  spliceAttrOutOfList(attr, declarator.getAttrListRef());
+  declarator.getAttributes().remove(&attr);
   state.addIgnoredTypeAttr(attr);
 }
 
 /// A function type attribute was written somewhere in a declaration
 /// *other* than on the declarator itself or in the decl spec.  Given
 /// that it didn't apply in whatever position it was written in, try
 /// to move it to a more appropriate position.
 static void distributeFunctionTypeAttr(TypeProcessingState &state,
                                        AttributeList &attr,
                                        QualType type) {
   Declarator &declarator = state.getDeclarator();
 
   // Try to push the attribute from the return type of a function to
   // the function itself.
   for (unsigned i = state.getCurrentChunkIndex(); i != 0; --i) {
     DeclaratorChunk &chunk = declarator.getTypeObject(i-1);
     switch (chunk.Kind) {
     case DeclaratorChunk::Function:
-      moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
-                             chunk.getAttrListRef());
+      moveAttrFromListToList(attr, state.getCurrentAttributes(),
+                             chunk.getAttrs());
       return;
 
     case DeclaratorChunk::Paren:
     case DeclaratorChunk::Pointer:
     case DeclaratorChunk::BlockPointer:
     case DeclaratorChunk::Array:
     case DeclaratorChunk::Reference:
     case DeclaratorChunk::MemberPointer:
     case DeclaratorChunk::Pipe:
       continue;
     }
   }
 
   diagnoseBadTypeAttribute(state.getSema(), attr, type);
 }
 
 /// Try to distribute a function type attribute to the innermost
 /// function chunk or type.  Returns true if the attribute was
 /// distributed, false if no location was found.
-static bool
-distributeFunctionTypeAttrToInnermost(TypeProcessingState &state,
-                                      AttributeList &attr,
-                                      AttributeList *&attrList,
-                                      QualType &declSpecType) {
+static bool distributeFunctionTypeAttrToInnermost(
+    TypeProcessingState &state, AttributeList &attr,
+    ParsedAttributesView &attrList, QualType &declSpecType) {
   Declarator &declarator = state.getDeclarator();
 
   // Put it on the innermost function chunk, if there is one.
   for (unsigned i = 0, e = declarator.getNumTypeObjects(); i != e; ++i) {
     DeclaratorChunk &chunk = declarator.getTypeObject(i);
     if (chunk.Kind != DeclaratorChunk::Function) continue;
 
-    moveAttrFromListToList(attr, attrList, chunk.getAttrListRef());
+    moveAttrFromListToList(attr, attrList, chunk.getAttrs());
     return true;
   }
 
   return handleFunctionTypeAttr(state, attr, declSpecType);
 }
 
 /// A function type attribute was written in the decl spec.  Try to
 /// apply it somewhere.
 static void
 distributeFunctionTypeAttrFromDeclSpec(TypeProcessingState &state,
                                        AttributeList &attr,
                                        QualType &declSpecType) {
   state.saveDeclSpecAttrs();
 
   // C++11 attributes before the decl specifiers actually appertain to
   // the declarators. Move them straight there. We don't support the
   // 'put them wherever you like' semantics we allow for GNU attributes.
   if (attr.isCXX11Attribute()) {
-    moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
-                           state.getDeclarator().getAttrListRef());
+    moveAttrFromListToList(attr, state.getCurrentAttributes(),
+                           state.getDeclarator().getAttributes());
     return;
   }
 
   // Try to distribute to the innermost.
-  if (distributeFunctionTypeAttrToInnermost(state, attr,
-                                            state.getCurrentAttrListRef(),
-                                            declSpecType))
+  if (distributeFunctionTypeAttrToInnermost(
+          state, attr, state.getCurrentAttributes(), declSpecType))
     return;
 
   // If that failed, diagnose the bad attribute when the declarator is
   // fully built.
   state.addIgnoredTypeAttr(attr);
 }
 
 /// A function type attribute was written on the declarator.  Try to
 /// apply it somewhere.
 static void
 distributeFunctionTypeAttrFromDeclarator(TypeProcessingState &state,
                                          AttributeList &attr,
                                          QualType &declSpecType) {
   Declarator &declarator = state.getDeclarator();
 
   // Try to distribute to the innermost.
-  if (distributeFunctionTypeAttrToInnermost(state, attr,
-                                            declarator.getAttrListRef(),
-                                            declSpecType))
+  if (distributeFunctionTypeAttrToInnermost(
+          state, attr, declarator.getAttributes(), declSpecType))
     return;
 
   // If that failed, diagnose the bad attribute when the declarator is
   // fully built.
-  spliceAttrOutOfList(attr, declarator.getAttrListRef());
+  declarator.getAttributes().remove(&attr);
   state.addIgnoredTypeAttr(attr);
 }
 
 /// Given that there are attributes written on the declarator
 /// itself, try to distribute any type attributes to the appropriate
 /// declarator chunk.
 ///
 /// These are attributes like the following:
 ///   int f ATTR;
 ///   int (f ATTR)();
 /// but not necessarily this:
 ///   int f() ATTR;
 static void distributeTypeAttrsFromDeclarator(TypeProcessingState &state,
                                               QualType &declSpecType) {
   // Collect all the type attributes from the declarator itself.
-  assert(state.getDeclarator().getAttributes() && "declarator has no attrs!");
-  AttributeList *attr = state.getDeclarator().getAttributes();
-  AttributeList *next;
-  do {
-    next = attr->getNext();
-
+  assert(!state.getDeclarator().getAttributes().empty() &&
+         "declarator has no attrs!");
+  // The called functions in this loop actually remove things from the current
+  // list, so iterating over the existing list isn't possible.  Instead, make a
+  // non-owning copy and iterate over that.
+  ParsedAttributesView AttrsCopy{state.getDeclarator().getAttributes()};
+  for (AttributeList &attr : AttrsCopy) {
     // Do not distribute C++11 attributes. They have strict rules for what
     // they appertain to.
-    if (attr->isCXX11Attribute())
+    if (attr.isCXX11Attribute())
       continue;
 
-    switch (attr->getKind()) {
+    switch (attr.getKind()) {
     OBJC_POINTER_TYPE_ATTRS_CASELIST:
-      distributeObjCPointerTypeAttrFromDeclarator(state, *attr, declSpecType);
+      distributeObjCPointerTypeAttrFromDeclarator(state, attr, declSpecType);
       break;
 
     FUNCTION_TYPE_ATTRS_CASELIST:
-      distributeFunctionTypeAttrFromDeclarator(state, *attr, declSpecType);
+      distributeFunctionTypeAttrFromDeclarator(state, attr, declSpecType);
       break;
 
     MS_TYPE_ATTRS_CASELIST:
       // Microsoft type attributes cannot go after the declarator-id.
       continue;
 
     NULLABILITY_TYPE_ATTRS_CASELIST:
       // Nullability specifiers cannot go after the declarator-id.
 
     // Objective-C __kindof does not get distributed.
     case AttributeList::AT_ObjCKindOf:
       continue;
 
     default:
       break;
     }
-  } while ((attr = next));
+  }
 }
 
 /// Add a synthetic '()' to a block-literal declarator if it is
 /// required, given the return type.
 static void maybeSynthesizeBlockSignature(TypeProcessingState &state,
                                           QualType declSpecType) {
   Declarator &declarator = state.getDeclarator();
 

 /// Return true if this is omitted block return type. Also check type
 /// attributes and type qualifiers when returning true.
 static bool checkOmittedBlockReturnType(Sema &S, Declarator &declarator,
                                         QualType Result) {
   if (!isOmittedBlockReturnType(declarator))
     return false;
 
   // Warn if we see type attributes for omitted return type on a block literal.
-  AttributeList *&attrs =
-      declarator.getMutableDeclSpec().getAttributes().getListRef();
-  AttributeList *prev = nullptr;
-  for (AttributeList *cur = attrs; cur; cur = cur->getNext()) {
-    AttributeList &attr = *cur;
-    // Skip attributes that were marked to be invalid or non-type
-    // attributes.
-    if (attr.isInvalid() || !attr.isTypeAttr()) {
-      prev = cur;
+  SmallVector<AttributeList *, 2> ToBeRemoved;
+  for (AttributeList &AL : declarator.getMutableDeclSpec().getAttributes()) {
+    if (AL.isInvalid() || !AL.isTypeAttr())
       continue;
-    }
-    S.Diag(attr.getLoc(),
+    S.Diag(AL.getLoc(),
            diag::warn_block_literal_attributes_on_omitted_return_type)
-        << attr.getName();
-    // Remove cur from the list.
-    if (prev) {
-      prev->setNext(cur->getNext());
-      prev = cur;
-    } else {
-      attrs = cur->getNext();
-    }
+        << AL.getName();
+    ToBeRemoved.push_back(&AL);
   }
+  // Remove bad attributes from the list.
+  for (AttributeList *AL : ToBeRemoved)
+    declarator.getMutableDeclSpec().getAttributes().remove(AL);
 
   // Warn if we see type qualifiers for omitted return type on a block literal.
   const DeclSpec &DS = declarator.getDeclSpec();
   unsigned TypeQuals = DS.getTypeQualifiers();
   diagnoseAndRemoveTypeQualifiers(S, DS, TypeQuals, Result, (unsigned)-1,
       diag::warn_block_literal_qualifiers_on_omitted_return_type);
   declarator.getMutableDeclSpec().ClearTypeQualifiers();
 
if (ObjCObjectTL.getType() == T)
     ObjCObjectTL.getBaseLoc().initializeFullCopy(BaseTypeInfo->getTypeLoc());
   else
     ObjCObjectTL.getBaseLoc().initialize(Context, Loc);
 
   // We're done. Return the completed type to the parser.
   return CreateParsedType(Result, ResultTInfo);
 }
 
-static OpenCLAccessAttr::Spelling getImageAccess(const AttributeList *Attrs) {
-  if (Attrs) {
-    const AttributeList *Next = Attrs;
-    do {
-      const AttributeList &Attr = *Next;
-      Next = Attr.getNext();
-      if (Attr.getKind() == AttributeList::AT_OpenCLAccess) {
-        return static_cast<OpenCLAccessAttr::Spelling>(
-            Attr.getSemanticSpelling());
-      }
-    } while (Next);
-  }
+static OpenCLAccessAttr::Spelling
+getImageAccess(const ParsedAttributesView &Attrs) {
+  for (const AttributeList &AL : Attrs)
+    if (AL.getKind() == AttributeList::AT_OpenCLAccess)
+      return static_cast<OpenCLAccessAttr::Spelling>(AL.getSemanticSpelling());
   return OpenCLAccessAttr::Keyword_read_only;
 }
 
 /// Convert the specified declspec to the appropriate type
 /// object.
 /// \param state Specifies the declarator containing the declaration specifier
 /// to be converted, along with other associated processing state.
 /// \returns The type described by the declaration specifiers.  This function
 /// never returns null.
 static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
   // FIXME: Should move the logic from DeclSpec::Finish to here for validity
   // checking.
 
   Sema &S = state.getSema();
   Declarator &declarator = state.getDeclarator();
-  const DeclSpec &DS = declarator.getDeclSpec();
+  DeclSpec &DS = declarator.getMutableDeclSpec();
   SourceLocation DeclLoc = declarator.getIdentifierLoc();
   if (DeclLoc.isInvalid())
     DeclLoc = DS.getLocStart();
 
   ASTContext &Context = S.Context;
 
   QualType Result;
   switch (DS.getTypeSpecType()) {
case DeclSpec::TST_atomic:
     assert(!Result.isNull() && "Didn't get a type for _Atomic?");
     Result = S.BuildAtomicType(Result, DS.getTypeSpecTypeLoc());
     if (Result.isNull()) {
       Result = Context.IntTy;
       declarator.setInvalidType(true);
     }
     break;
 
-#define GENERIC_IMAGE_TYPE(ImgType, Id) \
-  case DeclSpec::TST_##ImgType##_t: \
-    switch (getImageAccess(DS.getAttributes().getList())) { \
-    case OpenCLAccessAttr::Keyword_write_only: \
-      Result = Context.Id##WOTy; break; \
-    case OpenCLAccessAttr::Keyword_read_write: \
-      Result = Context.Id##RWTy; break; \
-    case OpenCLAccessAttr::Keyword_read_only: \
-      Result = Context.Id##ROTy; break; \
-    } \
+#define GENERIC_IMAGE_TYPE(ImgType, Id)                                        \
+  case DeclSpec::TST_##ImgType##_t:                                            \
+    switch (getImageAccess(DS.getAttributes())) {                              \
+    case OpenCLAccessAttr::Keyword_write_only:                                 \
+      Result = Context.Id##WOTy;                                               \
+      break;                                                                   \
+    case OpenCLAccessAttr::Keyword_read_write:                                 \
+      Result = Context.Id##RWTy;                                               \
+      break;                                                                   \
+    case OpenCLAccessAttr::Keyword_read_only:                                  \
+      Result = Context.Id##ROTy;                                               \
+      break;                                                                   \
+    }                                                                          \
     break;
 #include "clang/Basic/OpenCLImageTypes.def"
 
   case DeclSpec::TST_error:
     Result = Context.IntTy;
     declarator.setInvalidType(true);
     break;
   }
#include "clang/Basic/OpenCLImageTypes.def"
   if (declarator.getContext() == DeclaratorContext::BlockLiteralContext)
     maybeSynthesizeBlockSignature(state, Result);
 
   // Apply any type attributes from the decl spec.  This may cause the
   // list of type attributes to be temporarily saved while the type
   // attributes are pushed around.
   // pipe attributes will be handled later ( at GetFullTypeForDeclarator )
   if (!DS.isTypeSpecPipe())
-      processTypeAttrs(state, Result, TAL_DeclSpec, DS.getAttributes().getList());
+    processTypeAttrs(state, Result, TAL_DeclSpec, DS.getAttributes());
 
   // Apply const/volatile/restrict qualifiers to T.
   if (unsigned TypeQuals = DS.getTypeQualifiers()) {
     // Warn about CV qualifiers on function types.
     // C99 6.7.3p8:
     //   If the specification of a function type includes any type qualifiers,
     //   the behavior is undefined.
     // C++11 [dcl.fct]p7:
// the outermost pointer.
     if (!isBlockPointer && !declSpecType->isObjCObjectType())
       return;
 
     // Look for an explicit lifetime attribute there.
     DeclaratorChunk &chunk = declarator.getTypeObject(outermostPointerIndex);
     if (chunk.Kind != DeclaratorChunk::Pointer &&
         chunk.Kind != DeclaratorChunk::BlockPointer)
       return;
-    for (const AttributeList *attr = chunk.getAttrs(); attr;
-           attr = attr->getNext())
-      if (attr->getKind() == AttributeList::AT_ObjCOwnership)
+    for (const AttributeList &AL : chunk.getAttrs())
+      if (AL.getKind() == AttributeList::AT_ObjCOwnership)
         return;
 
     transferARCOwnershipToDeclaratorChunk(state, Qualifiers::OCL_Autoreleasing,
                                           outermostPointerIndex);
 
   // Any other number of pointers/references does not trigger the rule.
   } else return;
 
static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
 
   case UnqualifiedIdKind::IK_ConstructorName:
   case UnqualifiedIdKind::IK_ConstructorTemplateId:
   case UnqualifiedIdKind::IK_DestructorName:
     // Constructors and destructors don't have return types. Use
     // "void" instead.
     T = SemaRef.Context.VoidTy;
     processTypeAttrs(state, T, TAL_DeclSpec,
-                     D.getDeclSpec().getAttributes().getList());
+                     D.getMutableDeclSpec().getAttributes());
     break;
 
   case UnqualifiedIdKind::IK_DeductionGuideName:
     // Deduction guides have a trailing return type and no type in their
     // decl-specifier sequence. Use a placeholder return type for now.
     T = SemaRef.Context.DependentTy;
     break;
 
   case UnqualifiedIdKind::IK_ConversionFunctionId:
     // The result type of a conversion function is the type that it
     // converts to.
     T = SemaRef.GetTypeFromParser(D.getName().ConversionFunctionId,
                                   &ReturnTypeInfo);
     break;
   }
 
-  if (D.getAttributes())
+  if (!D.getAttributes().empty())
     distributeTypeAttrsFromDeclarator(state, T);
 
   // C++11 [dcl.spec.auto]p5: reject 'auto' if it is not in an allowed context.
   if (DeducedType *Deduced = T->getContainedDeducedType()) {
     AutoType *Auto = dyn_cast<AutoType>(Deduced);
     int Error = -1;
 
     // Is this a 'auto' or 'decltype(auto)' type (as opposed to __auto_type or
S.Diag(Paren.Loc, diag::note_remove_parens_for_variable_declaration)
       << FixItHint::CreateRemoval(Paren.Loc)
       << FixItHint::CreateRemoval(Paren.EndLoc);
 }
 
 /// Helper for figuring out the default CC for a function declarator type.  If
 /// this is the outermost chunk, then we can determine the CC from the
 /// declarator context.  If not, then this could be either a member function
 /// type or normal function type.
-static CallingConv
-getCCForDeclaratorChunk(Sema &S, Declarator &D,
-                        const DeclaratorChunk::FunctionTypeInfo &FTI,
-                        unsigned ChunkIndex) {
+static CallingConv getCCForDeclaratorChunk(
+    Sema &S, Declarator &D, const ParsedAttributesView &AttrList,
+    const DeclaratorChunk::FunctionTypeInfo &FTI, unsigned ChunkIndex) {
   assert(D.getTypeObject(ChunkIndex).Kind == DeclaratorChunk::Function);
 
   // Check for an explicit CC attribute.
-  for (auto Attr = FTI.AttrList; Attr; Attr = Attr->getNext()) {
-    switch (Attr->getKind()) {
-    CALLING_CONV_ATTRS_CASELIST: {
+  for (const AttributeList &AL : AttrList) {
+    switch (AL.getKind()) {
+    CALLING_CONV_ATTRS_CASELIST : {
       // Ignore attributes that don't validate or can't apply to the
       // function type.  We'll diagnose the failure to apply them in
       // handleFunctionTypeAttr.
       CallingConv CC;
-      if (!S.CheckCallingConvAttr(*Attr, CC) &&
+      if (!S.CheckCallingConvAttr(AL, CC) &&
           (!FTI.isVariadic || supportsVariadicCall(CC))) {
         return CC;
       }
       break;
     }
 
     default:
       break;
static CallingConv getCCForDeclaratorChunk(
   CallingConv CC = S.Context.getDefaultCallingConvention(FTI.isVariadic,
                                                          IsCXXInstanceMethod);
 
   // Attribute AT_OpenCLKernel affects the calling convention for SPIR
   // and AMDGPU targets, hence it cannot be treated as a calling
   // convention attribute. This is the simplest place to infer
   // calling convention for OpenCL kernels.
   if (S.getLangOpts().OpenCL) {
-    for (const AttributeList *Attr = D.getDeclSpec().getAttributes().getList();
-         Attr; Attr = Attr->getNext()) {
-      if (Attr->getKind() == AttributeList::AT_OpenCLKernel) {
+    for (const AttributeList &AL : D.getDeclSpec().getAttributes()) {
+      if (AL.getKind() == AttributeList::AT_OpenCLKernel) {
         CC = CC_OpenCLKernel;
         break;
       }
     }
   }
 
   return CC;
 }
IdentifierInfo *Sema::getNSErrorIdent() {
   if (!Ident_NSError)
     Ident_NSError = PP.getIdentifierInfo("NSError");
 
   return Ident_NSError;
 }
 
 /// Check whether there is a nullability attribute of any kind in the given
 /// attribute list.
-static bool hasNullabilityAttr(const AttributeList *attrs) {
-  for (const AttributeList *attr = attrs; attr;
-       attr = attr->getNext()) {
-    if (attr->getKind() == AttributeList::AT_TypeNonNull ||
-        attr->getKind() == AttributeList::AT_TypeNullable ||
-        attr->getKind() == AttributeList::AT_TypeNullUnspecified)
+static bool hasNullabilityAttr(const ParsedAttributesView &attrs) {
+  for (const AttributeList &AL : attrs) {
+    if (AL.getKind() == AttributeList::AT_TypeNonNull ||
+        AL.getKind() == AttributeList::AT_TypeNullable ||
+        AL.getKind() == AttributeList::AT_TypeNullUnspecified)
       return true;
   }
 
   return false;
 }
 
 namespace {
   /// Describes the kind of a pointer a declarator describes.
case DeclaratorContext::KNRTypeListContext: {
           inferNullability = NullabilityKind::Nullable;
         break;
 
       case PointerDeclaratorKind::MaybePointerToCFRef:
         if (isFunctionOrMethod) {
           // On pointer-to-pointer parameters marked cf_returns_retained or
           // cf_returns_not_retained, if the outer pointer is explicit then
           // infer the inner pointer as _Nullable.
-          auto hasCFReturnsAttr = [](const AttributeList *NextAttr) -> bool {
-            while (NextAttr) {
-              if (NextAttr->getKind() == AttributeList::AT_CFReturnsRetained ||
-                  NextAttr->getKind() == AttributeList::AT_CFReturnsNotRetained)
-                return true;
-              NextAttr = NextAttr->getNext();
-            }
-            return false;
+          auto hasCFReturnsAttr =
+              [](const ParsedAttributesView &AttrList) -> bool {
+            return AttrList.hasAttribute(AttributeList::AT_CFReturnsRetained) ||
+                   AttrList.hasAttribute(
+                       AttributeList::AT_CFReturnsNotRetained);
           };
           if (const auto *InnermostChunk = D.getInnermostNonParenChunk()) {
             if (hasCFReturnsAttr(D.getAttributes()) ||
                 hasCFReturnsAttr(InnermostChunk->getAttrs()) ||
-                hasCFReturnsAttr(D.getDeclSpec().getAttributes().getList())) {
+                hasCFReturnsAttr(D.getDeclSpec().getAttributes())) {
               inferNullability = NullabilityKind::Nullable;
               inferNullabilityInnerOnly = true;
             }
           }
         }
         break;
       }
       break;
do {
           return true;
       typedefTy = typedefTy->desugar()->getAs<TypedefType>();
     } while (typedefTy);
     return false;
   };
 
   // Local function that checks the nullability for a given pointer declarator.
   // Returns true if _Nonnull was inferred.
-  auto inferPointerNullability = [&](SimplePointerKind pointerKind,
-                                     SourceLocation pointerLoc,
-                                     SourceLocation pointerEndLoc,
-                                     AttributeList *&attrs) -> AttributeList * {
+  auto inferPointerNullability =
+      [&](SimplePointerKind pointerKind, SourceLocation pointerLoc,
+          ParsedAttributesView &attrs) -> AttributeList * {
     // We've seen a pointer.
     if (NumPointersRemaining > 0)
       --NumPointersRemaining;
 
     // If a nullability attribute is present, there's nothing to do.
     if (hasNullabilityAttr(attrs))
       return nullptr;
 
     // If we're supposed to infer nullability, do so now.
     if (inferNullability && !inferNullabilityInnerOnlyComplete) {
       AttributeList::Syntax syntax
         = inferNullabilityCS ? AttributeList::AS_ContextSensitiveKeyword
                              : AttributeList::AS_Keyword;
       AttributeList *nullabilityAttr = state.getDeclarator().getAttributePool()
                                          .create(
                                            S.getNullabilityKeyword(
                                              *inferNullability),
                                            SourceRange(pointerLoc),
                                            nullptr, SourceLocation(),
                                            nullptr, 0, syntax);
 
-      spliceAttrIntoList(*nullabilityAttr, attrs);
+      attrs.addAtStart(nullabilityAttr);
 
       if (inferNullabilityCS) {
         state.getDeclarator().getMutableDeclSpec().getObjCQualifiers()
           ->setObjCDeclQualifier(ObjCDeclSpec::DQ_CSNullability);
       }
 
       if (pointerLoc.isValid() &&
           complainAboutInferringWithinChunk !=
if (T->canHaveNullability(/*ResultIfUnknown*/false) &&
       } else {
         SimplePointerKind pointerKind = SimplePointerKind::Pointer;
         if (T->isBlockPointerType())
           pointerKind = SimplePointerKind::BlockPointer;
         else if (T->isMemberPointerType())
           pointerKind = SimplePointerKind::MemberPointer;
 
         if (auto *attr = inferPointerNullability(
                 pointerKind, D.getDeclSpec().getTypeSpecTypeLoc(),
                 D.getDeclSpec().getLocEnd(),
-              D.getMutableDeclSpec().getAttributes().getListRef())) {
+                D.getMutableDeclSpec().getAttributes())) {
           T = Context.getAttributedType(
                 AttributedType::getNullabilityAttrKind(*inferNullability),T,T);
           attr->setUsedAsTypeAttr();
         }
       }
     }
 
     if (complainAboutMissingNullability == CAMN_Yes &&
case DeclaratorChunk::Paren:
       break;
     case DeclaratorChunk::BlockPointer:
       // If blocks are disabled, emit an error.
       if (!LangOpts.Blocks)
         S.Diag(DeclType.Loc, diag::err_blocks_disable) << LangOpts.OpenCL;
 
       // Handle pointer nullability.
       inferPointerNullability(SimplePointerKind::BlockPointer, DeclType.Loc,
-                              DeclType.EndLoc, DeclType.getAttrListRef());
+                              DeclType.EndLoc, DeclType.getAttrs());
 
       T = S.BuildBlockPointerType(T, D.getIdentifierLoc(), Name);
       if (DeclType.Cls.TypeQuals || LangOpts.OpenCL) {
         // OpenCL v2.0, s6.12.5 - Block variable declarations are implicitly
         // qualified with const.
         if (LangOpts.OpenCL)
           DeclType.Cls.TypeQuals |= DeclSpec::TQ_const;
         T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Cls.TypeQuals);
       }
       break;
     case DeclaratorChunk::Pointer:
       // Verify that we're not building a pointer to pointer to function with
       // exception specification.
       if (LangOpts.CPlusPlus && S.CheckDistantExceptionSpec(T)) {
         S.Diag(D.getIdentifierLoc(), diag::err_distant_exception_spec);
         D.setInvalidType(true);
         // Build the type anyway.
       }
 
       // Handle pointer nullability
       inferPointerNullability(SimplePointerKind::Pointer, DeclType.Loc,
-                              DeclType.EndLoc, DeclType.getAttrListRef());
+                              DeclType.EndLoc, DeclType.getAttrs());
 
       if (LangOpts.ObjC1 && T->getAs<ObjCObjectType>()) {
         T = Context.getObjCObjectPointerType(T);
         if (DeclType.Ptr.TypeQuals)
           T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Ptr.TypeQuals);
         break;
       }
 
case DeclaratorChunk::Function: {
 
       // Objective-C ARC ownership qualifiers are ignored on the function
       // return type (by type canonicalization). Complain if this attribute
       // was written here.
       if (T.getQualifiers().hasObjCLifetime()) {
         SourceLocation AttrLoc;
         if (chunkIndex + 1 < D.getNumTypeObjects()) {
           DeclaratorChunk ReturnTypeChunk = D.getTypeObject(chunkIndex + 1);
-          for (const AttributeList *Attr = ReturnTypeChunk.getAttrs();
-               Attr; Attr = Attr->getNext()) {
-            if (Attr->getKind() == AttributeList::AT_ObjCOwnership) {
-              AttrLoc = Attr->getLoc();
+          for (const AttributeList &AL : ReturnTypeChunk.getAttrs()) {
+            if (AL.getKind() == AttributeList::AT_ObjCOwnership) {
+              AttrLoc = AL.getLoc();
               break;
             }
           }
         }
         if (AttrLoc.isInvalid()) {
-          for (const AttributeList *Attr
-                 = D.getDeclSpec().getAttributes().getList();
-               Attr; Attr = Attr->getNext()) {
-            if (Attr->getKind() == AttributeList::AT_ObjCOwnership) {
-              AttrLoc = Attr->getLoc();
+          for (const AttributeList &AL : D.getDeclSpec().getAttributes()) {
+            if (AL.getKind() == AttributeList::AT_ObjCOwnership) {
+              AttrLoc = AL.getLoc();
               break;
             }
           }
         }
 
         if (AttrLoc.isValid()) {
           // The ownership attributes are almost always written via
           // the predefined
case DeclaratorChunk::Function: {
             << (D.getContext() == DeclaratorContext::AliasDeclContext ||
                 D.getContext() == DeclaratorContext::AliasTemplateContext);
 
       // If we see "T var();" or "T var(T());" at block scope, it is probably
       // an attempt to initialize a variable, not a function declaration.
       if (FTI.isAmbiguous)
         warnAboutAmbiguousFunction(S, D, DeclType, T);
 
-      FunctionType::ExtInfo EI(getCCForDeclaratorChunk(S, D, FTI, chunkIndex));
+      FunctionType::ExtInfo EI(
+          getCCForDeclaratorChunk(S, D, DeclType.getAttrs(), FTI, chunkIndex));
 
       if (!FTI.NumParams && !FTI.isVariadic && !LangOpts.CPlusPlus
                                             && !LangOpts.OpenCL) {
         // Simple void foo(), where the incoming T is the result type.
         T = Context.getFunctionNoProtoType(T, EI);
       } else {
         // We allow a zero-parameter variadic function in C if the
         // function is marked with the "overloadable" attribute. Scan
         // for this attribute now.
-        if (!FTI.NumParams && FTI.isVariadic && !LangOpts.CPlusPlus) {
-          bool Overloadable = false;
-          for (const AttributeList *Attrs = D.getAttributes();
-               Attrs; Attrs = Attrs->getNext()) {
-            if (Attrs->getKind() == AttributeList::AT_Overloadable) {
-              Overloadable = true;
-              break;
-            }
-          }
-
-          if (!Overloadable)
+        if (!FTI.NumParams && FTI.isVariadic && !LangOpts.CPlusPlus)
+          if (!D.getAttributes().hasAttribute(AttributeList::AT_Overloadable))
             S.Diag(FTI.getEllipsisLoc(), diag::err_ellipsis_first_param);
-        }
 
         if (FTI.NumParams && FTI.Params[0].Param == nullptr) {
           // C99 6.7.5.3p3: Reject int(x,y,z) when it's not a function
           // definition.
           S.Diag(FTI.Params[0].IdentLoc,
                  diag::err_ident_list_in_fn_declaration);
           D.setInvalidType(true);
           // Recover by creating a K&R-style function type.
for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
     }
     case DeclaratorChunk::MemberPointer: {
       // The scope spec must refer to a class, or be dependent.
       CXXScopeSpec &SS = DeclType.Mem.Scope();
       QualType ClsType;
 
       // Handle pointer nullability.
       inferPointerNullability(SimplePointerKind::MemberPointer, DeclType.Loc,
-                              DeclType.EndLoc, DeclType.getAttrListRef());
+                              DeclType.EndLoc, DeclType.getAttrs());
 
       if (SS.isInvalid()) {
         // Avoid emitting extra errors if we already errored on the scope.
         D.setInvalidType(true);
       } else if (S.isDependentScopeSpecifier(SS) ||
                  dyn_cast_or_null<CXXRecordDecl>(S.computeDeclContext(SS))) {
         NestedNameSpecifier *NNS = SS.getScopeRep();
         NestedNameSpecifier *NNSPrefix = NNS->getPrefix();
case DeclaratorChunk::MemberPointer: {
         T = S.BuildQualifiedType(T, DeclType.Loc, DeclType.Mem.TypeQuals);
       }
       break;
     }
 
     case DeclaratorChunk::Pipe: {
       T = S.BuildReadPipeType(T, DeclType.Loc);
       processTypeAttrs(state, T, TAL_DeclSpec,
-                       D.getDeclSpec().getAttributes().getList());
+                       D.getMutableDeclSpec().getAttributes());
       break;
     }
     }
 
     if (T.isNull()) {
       D.setInvalidType(true);
       T = Context.IntTy;
     }
 
     // See if there are any attributes on this declarator chunk.
-    processTypeAttrs(state, T, TAL_DeclChunk,
-                     const_cast<AttributeList *>(DeclType.getAttrs()));
+    processTypeAttrs(state, T, TAL_DeclChunk, DeclType.getAttrs());
   }
 
   // GNU warning -Wstrict-prototypes
   //   Warn if a function declaration is without a prototype.
   //   This warning is issued for all kinds of unprototyped function
   //   declarations (i.e. function type typedef, function pointer etc.)
   //   C99 6.7.5.3p14:
   //   The empty list in a function declarator that is not part of a definition

 
 static void transferARCOwnershipToDeclaratorChunk(TypeProcessingState &state,
                                             Qualifiers::ObjCLifetime ownership,
                                             unsigned chunkIndex) {
   Sema &S = state.getSema();
   Declarator &D = state.getDeclarator();
 
   // Look for an explicit lifetime attribute.
   DeclaratorChunk &chunk = D.getTypeObject(chunkIndex);
-  for (const AttributeList *attr = chunk.getAttrs(); attr;
-         attr = attr->getNext())
-    if (attr->getKind() == AttributeList::AT_ObjCOwnership)
-      return;
+  if (chunk.getAttrs().hasAttribute(AttributeList::AT_ObjCOwnership))
 
   const char *attrStr = nullptr;
   switch (ownership) {
   case Qualifiers::OCL_None: llvm_unreachable("no ownership!");
   case Qualifiers::OCL_ExplicitNone: attrStr = "none"; break;
   case Qualifiers::OCL_Strong: attrStr = "strong"; break;
   case Qualifiers::OCL_Weak: attrStr = "weak"; break;
   case Qualifiers::OCL_Autoreleasing: attrStr = "autoreleasing"; break;
   }
 
   IdentifierLoc *Arg = new (S.Context) IdentifierLoc;
   Arg->Ident = &S.Context.Idents.get(attrStr);
   Arg->Loc = SourceLocation();
 
   ArgsUnion Args(Arg);
 
   // If there wasn't one, add one (with an invalid source location
   // so that we don't make an AttributedType for it).
   AttributeList *attr = D.getAttributePool()
     .create(&S.Context.Idents.get("objc_ownership"), SourceLocation(),
             /*scope*/ nullptr, SourceLocation(),
             /*args*/ &Args, 1, AttributeList::AS_GNU);
-  spliceAttrIntoList(*attr, chunk.getAttrListRef());
-
+  chunk.getAttrs().addAtStart(attr);
   // TODO: mark whether we did this inference?
 }
 
 /// Used for transferring ownership in casts resulting in l-values.
 static void transferARCOwnership(TypeProcessingState &state,
                                  QualType &declSpecTy,
                                  Qualifiers::ObjCLifetime ownership) {
   Sema &S = state.getSema();
static AttributeList::Kind getAttrListKind(AttributedType::Kind kind) {
   case AttributedType::attr_objc_kindof:
     return AttributeList::AT_ObjCKindOf;
   case AttributedType::attr_ns_returns_retained:
     return AttributeList::AT_NSReturnsRetained;
   }
   llvm_unreachable("unexpected attribute kind!");
 }
 
-static void fillAttributedTypeLoc(AttributedTypeLoc TL,
-                                  const AttributeList *attrs,
-                                  const AttributeList *DeclAttrs = nullptr) {
-  // DeclAttrs and attrs cannot be both empty.
-  assert((attrs || DeclAttrs) &&
-         "no type attributes in the expected location!");
-
-  AttributeList::Kind parsedKind = getAttrListKind(TL.getAttrKind());
-  // Try to search for an attribute of matching kind in attrs list.
-  while (attrs && attrs->getKind() != parsedKind)
-    attrs = attrs->getNext();
-  if (!attrs) {
-    // No matching type attribute in attrs list found.
-    // Try searching through C++11 attributes in the declarator attribute list.
-    while (DeclAttrs && (!DeclAttrs->isCXX11Attribute() ||
-                         DeclAttrs->getKind() != parsedKind))
-      DeclAttrs = DeclAttrs->getNext();
-    attrs = DeclAttrs;
-  }
-
-  assert(attrs && "no matching type attribute in expected location!");
-
-  TL.setAttrNameLoc(attrs->getLoc());
+static void setAttributedTypeLoc(AttributedTypeLoc TL,
+                                 const AttributeList &attr) {
+  TL.setAttrNameLoc(attr.getLoc());
   if (TL.hasAttrExprOperand()) {
-    assert(attrs->isArgExpr(0) && "mismatched attribute operand kind");
-    TL.setAttrExprOperand(attrs->getArgAsExpr(0));
+    assert(attr.isArgExpr(0) && "mismatched attribute operand kind");
+    TL.setAttrExprOperand(attr.getArgAsExpr(0));
   } else if (TL.hasAttrEnumOperand()) {
-    assert((attrs->isArgIdent(0) || attrs->isArgExpr(0)) &&
+    assert((attr.isArgIdent(0) || attr.isArgExpr(0)) &&
            "unexpected attribute operand kind");
-    if (attrs->isArgIdent(0))
-      TL.setAttrEnumOperandLoc(attrs->getArgAsIdent(0)->Loc);
+    if (attr.isArgIdent(0))
+      TL.setAttrEnumOperandLoc(attr.getArgAsIdent(0)->Loc);
     else
-      TL.setAttrEnumOperandLoc(attrs->getArgAsExpr(0)->getExprLoc());
+      TL.setAttrEnumOperandLoc(attr.getArgAsExpr(0)->getExprLoc());
   }
 
   // FIXME: preserve this information to here.
   if (TL.hasAttrOperand())
     TL.setAttrOperandParensRange(SourceRange());
 }
 
+static void fillAttributedTypeLoc(AttributedTypeLoc TL,
+                                  const ParsedAttributesView &Attrs,
+                                  const ParsedAttributesView &DeclAttrs) {
+  // DeclAttrs and Attrs cannot be both empty.
+  assert((!Attrs.empty() || !DeclAttrs.empty()) &&
+         "no type attributes in the expected location!");
+
+  AttributeList::Kind parsedKind = getAttrListKind(TL.getAttrKind());
+  // Try to search for an attribute of matching kind in Attrs list.
+  for (const AttributeList &AL : Attrs)
+    if (AL.getKind() == parsedKind)
+      return setAttributedTypeLoc(TL, AL);
+
+  for (const AttributeList &AL : DeclAttrs)
+    if (AL.isCXX11Attribute() || AL.getKind() == parsedKind)
+      return setAttributedTypeLoc(TL, AL);
+  llvm_unreachable("no matching type attribute in expected location!");
+}
+
 namespace {
   class TypeSpecLocFiller : public TypeLocVisitor<TypeSpecLocFiller> {
     ASTContext &Context;
     const DeclSpec &DS;
 
   public:
     TypeSpecLocFiller(ASTContext &Context, const DeclSpec &DS)
       : Context(Context), DS(DS) {}
 
     void VisitAttributedTypeLoc(AttributedTypeLoc TL) {
-      fillAttributedTypeLoc(TL, DS.getAttributes().getList());
+      fillAttributedTypeLoc(TL, DS.getAttributes(), ParsedAttributesView{});
       Visit(TL.getModifiedLoc());
     }
     void VisitQualifiedTypeLoc(QualifiedTypeLoc TL) {
       Visit(TL.getUnqualifiedLoc());
     }
     void VisitTypedefTypeLoc(TypedefTypeLoc TL) {
       TL.setNameLoc(DS.getTypeSpecTypeLoc());
     }
public:
     void VisitQualifiedTypeLoc(QualifiedTypeLoc TL) {
       llvm_unreachable("qualified type locs not expected here!");
     }
     void VisitDecayedTypeLoc(DecayedTypeLoc TL) {
       llvm_unreachable("decayed type locs not expected here!");
     }
 
     void VisitAttributedTypeLoc(AttributedTypeLoc TL) {
-      fillAttributedTypeLoc(TL, Chunk.getAttrs());
+      fillAttributedTypeLoc(TL, Chunk.getAttrs(), ParsedAttributesView{});
     }
     void VisitAdjustedTypeLoc(AdjustedTypeLoc TL) {
       // nothing
     }
     void VisitBlockPointerTypeLoc(BlockPointerTypeLoc TL) {
       assert(Chunk.Kind == DeclaratorChunk::BlockPointer);
       TL.setCaretLoc(Chunk.Loc);
     }
case DeclaratorChunk::MemberPointer:
     // FIXME: Provide a source location for the _Atomic keyword.
     break;
   }
 
   ATL.setKWLoc(Loc);
   ATL.setParensRange(SourceRange());
 }
 
-static void fillDependentAddressSpaceTypeLoc(DependentAddressSpaceTypeLoc DASTL, 
-                                             const AttributeList *Attrs) {
-  while (Attrs && Attrs->getKind() != AttributeList::AT_AddressSpace)
-    Attrs = Attrs->getNext();
-
-  assert(Attrs && "no address_space attribute found at the expected location!");
-  
-  DASTL.setAttrNameLoc(Attrs->getLoc());
-  DASTL.setAttrExprOperand(Attrs->getArgAsExpr(0));
+static void
+fillDependentAddressSpaceTypeLoc(DependentAddressSpaceTypeLoc DASTL,
+                                 const ParsedAttributesView &Attrs) {
+  for (const AttributeList &AL : Attrs) {
+    if (AL.getKind() == AttributeList::AT_AddressSpace) {
+      DASTL.setAttrNameLoc(AL.getLoc());
+      DASTL.setAttrExprOperand(AL.getArgAsExpr(0));
       DASTL.setAttrOperandParensRange(SourceRange());
+      return;
+    }
+  }
+
+  llvm_unreachable(
+      "no address_space attribute found at the expected location!");
 }
 
 /// Create and instantiate a TypeSourceInfo with type source information.
 ///
 /// \param T QualType referring to the type as written in source code.
 ///
 /// \param ReturnTypeInfo For declarators whose return type does not show
 /// up in the normal place in the declaration specifiers (such as a C++
 /// conversion function), this pointer will refer to a type source information
 /// for that return type.
 TypeSourceInfo *
 Sema::GetTypeSourceInfoForDeclarator(Declarator &D, QualType T,
                                      TypeSourceInfo *ReturnTypeInfo) {
   TypeSourceInfo *TInfo = Context.CreateTypeSourceInfo(T);
   UnqualTypeLoc CurrTL = TInfo->getTypeLoc().getUnqualifiedLoc();
-  const AttributeList *DeclAttrs = D.getAttributes();
 
   // Handle parameter packs whose type is a pack expansion.
   if (isa<PackExpansionType>(T)) {
     CurrTL.castAs<PackExpansionTypeLoc>().setEllipsisLoc(D.getEllipsisLoc());
     CurrTL = CurrTL.getNextTypeLoc().getUnqualifiedLoc();
   }
 
   for (unsigned i = 0, e = D.getNumTypeObjects(); i != e; ++i) {
     
     if (DependentAddressSpaceTypeLoc DASTL =
         CurrTL.getAs<DependentAddressSpaceTypeLoc>()) {
       fillDependentAddressSpaceTypeLoc(DASTL, D.getTypeObject(i).getAttrs());
       CurrTL = DASTL.getPointeeTypeLoc().getUnqualifiedLoc();  
     }
 
     // An AtomicTypeLoc might be produced by an atomic qualifier in this
     // declarator chunk.
     if (AtomicTypeLoc ATL = CurrTL.getAs<AtomicTypeLoc>()) {
       fillAtomicQualLoc(ATL, D.getTypeObject(i));
       CurrTL = ATL.getValueLoc().getUnqualifiedLoc();
     }
 
     while (AttributedTypeLoc TL = CurrTL.getAs<AttributedTypeLoc>()) {
-      fillAttributedTypeLoc(TL, D.getTypeObject(i).getAttrs(), DeclAttrs);
+      fillAttributedTypeLoc(TL, D.getTypeObject(i).getAttrs(),
+                            D.getAttributes());
       CurrTL = TL.getNextTypeLoc().getUnqualifiedLoc();
     }
 
     // FIXME: Ordering here?
     while (AdjustedTypeLoc TL = CurrTL.getAs<AdjustedTypeLoc>())
       CurrTL = TL.getNextTypeLoc().getUnqualifiedLoc();
 
     DeclaratorLocFiller(Context, D.getTypeObject(i)).Visit(CurrTL);
static bool distributeNullabilityTypeAttr(TypeProcessingState &state,
                                           QualType type,
                                           AttributeList &attr) {
   Declarator &declarator = state.getDeclarator();
 
   /// Attempt to move the attribute to the specified chunk.
   auto moveToChunk = [&](DeclaratorChunk &chunk, bool inFunction) -> bool {
     // If there is already a nullability attribute there, don't add
     // one.
-    if (hasNullabilityAttr(chunk.getAttrListRef()))
+    if (hasNullabilityAttr(chunk.getAttrs()))
       return false;
 
     // Complain about the nullability qualifier being in the wrong
     // place.
     enum {
       PK_Pointer,
       PK_BlockPointer,
       PK_MemberPointer,
auto moveToChunk = [&](DeclaratorChunk &chunk, bool inFunction) -> bool {
     if (chunk.Kind != DeclaratorChunk::MemberPointer) {
       diag << FixItHint::CreateRemoval(attr.getLoc())
            << FixItHint::CreateInsertion(
                 state.getSema().getPreprocessor()
                   .getLocForEndOfToken(chunk.Loc),
                 " " + attr.getName()->getName().str() + " ");
     }
 
-    moveAttrFromListToList(attr, state.getCurrentAttrListRef(),
-                           chunk.getAttrListRef());
+    moveAttrFromListToList(attr, state.getCurrentAttributes(),
+                           chunk.getAttrs());
     return true;
   };
 
   // Move it to the outermost pointer, member pointer, or block
   // pointer declarator.
   for (unsigned i = state.getCurrentChunkIndex(); i != 0; --i) {
     DeclaratorChunk &chunk = declarator.getTypeObject(i-1);
     switch (chunk.Kind) {
if (IsPointee) {
         }
       }
     }
   }
   T = State.getSema().Context.getAddrSpaceQualType(T, ImpAddr);
 }
 
 static void processTypeAttrs(TypeProcessingState &state, QualType &type,
-                             TypeAttrLocation TAL, AttributeList *attrs) {
+                             TypeAttrLocation TAL,
+                             ParsedAttributesView &attrs) {
   // Scan through and apply attributes to this type where it makes sense.  Some
   // attributes (such as __address_space__, __vector_size__, etc) apply to the
   // type, but others can be present in the type specifiers even though they
   // apply to the decl.  Here we apply type attributes and ignore the rest.
 
-  while (attrs) {
-    AttributeList &attr = *attrs;
-    attrs = attr.getNext(); // reset to the next here due to early loop continue
-                            // stmts
+  // This loop modifies the list pretty frequently, but we still need to make
+  // sure we visit every element once. Copy the attributes list, and iterate
+  // over that.
+  ParsedAttributesView AttrsCopy{attrs};
+  for (AttributeList &attr : AttrsCopy) {
 
     // Skip attributes that were marked to be invalid.
     if (attr.isInvalid())
       continue;
 
     if (attr.isCXX11Attribute()) {
       // [[gnu::...]] attributes are treated as declaration attributes, so may
       // not appertain to a DeclaratorChunk. If we handle them as type