[AST] Store "UsesADL" information in CallExpr.

[EricWF]

Summary

Currently the Clang AST doesn't store information about how the callee of a CallExpr was found. Specifically if it was found using ADL.

However, this information is invaluable to tooling. Consider a tool which renames usages of a function. If the originally CallExpr was formed using ADL, then the tooling may need to additionally qualify the replacement.
Without information about how the callee was found, the tooling is left scratching it's head. Additionally, we want to be able to match ADL calls as quickly as possible, which means avoiding computing the answer on the fly.

This patch changes CallExpr to store whether it's callee was found using ADL. It does not change the size of any AST nodes.

[fowles]

include/clang/AST/ExprCXX.h

218

Can CUDAKernelCalls ever use ADL?

499

Same question, I assume user defined literals can only be called as string suffixes and thus never get ADL

include/clang/ASTMatchers/ASTMatchers.h

1275

y(42); // Doesn't match

include/clang/Sema/Overload.h

775

maybe bit pack these? I think overload sets for operator<< actually get pretty big

lib/Sema/SemaOverload.cpp

8946

should this fix be in a separate change?

12024

/*IsExecConfig=*/

12077

here too

lib/Serialization/ASTReaderStmt.cpp

735

readInt into a bool?

unittests/ASTMatchers/ASTMatchersNodeTest.cpp

204

if you use cc or cpp as your delimiter, I think clang-format will recurse correctly

[EricWF]

Address review comments. Fixes incoming.

include/clang/AST/ExprCXX.h

218

Yeah, after further investigation, I don't think so. I'll revert this change.

499

Right. Their argument is a literal of some sort.

lib/Sema/SemaOverload.cpp

8946

I'll commit the fix as a separate patch.

lib/Serialization/ASTReaderStmt.cpp

735

Yeah. You serialize and serialize all integer types using readInt()

unittests/ASTMatchers/ASTMatchersNodeTest.cpp

204

That's super cool. Thanks!

[riccibruno]

include/clang/AST/Expr.h

2425

There is no need to pass this flag to the empty constructor
since it is going to be deserialized in ASTReaderStmt.
Only what is strictly needed to create the empty CallExpr
is passed here. In fact if you wanted to pass the flag when creating
the empty CallExpr you would have to update what is
under case EXPR_CALL: in ASTReader::ReadStmtFromStream.

include/clang/AST/ExprCXX.h

106

same

178

same

224

same

505

same

lib/Serialization/ASTReaderStmt.cpp

741

E->setUsesADL(Record.readInt()) with the
bool UsesADL = Record.readInt(); removed ?

[EricWF]

Address more review comments. Update incoming.

include/clang/AST/Expr.h

2425

Ack. Thanks for the explanation.

[EricWF]

Update with fixes for review comments.

[riccibruno]

lib/AST/Expr.cpp

1267

It do not really matter but there is not point initializing this bit here.

[aaron.ballman]

include/clang/ASTMatchers/ASTMatchers.h

1260

Don't forget to regenerate the documentation and update Registry.cpp to add clang-query support.

[EricWF]

More tests.

[EricWF]

Register matcher and regenerate docs.

[aaron.ballman]

A few more minor nits.

docs/LibASTMatchersReference.html

2579–2581 ↗

(On Diff #177720)

This is not your bug to fix, but it seems the documentation generator is stripping the comment markers. This impacts other matchers as well, such as throughUsingDecl().

include/clang/Sema/Overload.h

831

OverloadCandidate set -> OverloadCandidateSet ? (I'd also be fine with removing the comment -- seems somewhat obvious from context.)

lib/Sema/SemaExpr.cpp

5672

No need to add the braces here (alternatively, add them to the else clause).

unittests/ASTMatchers/ASTMatchersNodeTest.cpp

204

Wow, that is really neat!

[EricWF]

Address more inline comments.

docs/LibASTMatchersReference.html

2579–2581 ↗

(On Diff #177720)

I wonder if it strips /**/ comments. I don't want to get blocked on this.

lib/AST/Expr.cpp

1267

I'm a but nervous MSAN won't catch an uninitialized read because it's a bitfield, so I would rather be safe than sorry?

[aaron.ballman]

docs/LibASTMatchersReference.html

2579–2581 ↗

(On Diff #177720)

Don't let it block you -- I'm poking at a fix currently, but this is not your bug.

[riccibruno]

lib/AST/Expr.cpp

1267

I believe that msan can cope with bit level operations just fine.
What I am afraid is that initializing it here will hide the
fact that it is not initialized during deserialization if the
E->setUsesADL(Record.readInt()); is removed by mistake.

At least not initializing it here will leave a chance for msan
to catch this.

[rsmith]

include/clang/Sema/Sema.h

2758

Long lists of bool arguments make me nervous, especially with default arguments. Can you introduce an enum for the new param at least?

lib/AST/ASTImporter.cpp

7387

Do we need to pass through the usesADL flag here too?

lib/AST/Expr.cpp

1267

IIRC all the ExprBits get initialized by the Expr(EmptyShell) ctor.

lib/Sema/SemaExpr.cpp

5673

If you believe that CUDA kernel calls can't find functions with ADL, please add an assert here.

[riccibruno]

lib/AST/Expr.cpp

1267

I don't think they do.

[EricWF]

include/clang/Sema/Sema.h

2758

Ack. I was thinking the same thing.

lib/AST/ASTImporter.cpp

7387

Seems like it. I'll add tests as well.

lib/AST/Expr.cpp

1267

Regardless. I'll remove the initialization.

I think potentially getting a random value will make it easier to spot bugs.

[EricWF]

Address review comments.

[EricWF]

I think this is good to go. Any more comments?

include/clang/Sema/Sema.h

2758

And you were right to be nervous. The change found bugs.

[EricWF]

docs/LibASTMatchersReference.html

2579–2581 ↗

(On Diff #177720)

Thanks for the fix!

[rsmith]

include/clang/ASTMatchers/ASTMatchers.h

1276

I think it would be useful to add to the example:

using NS::y;
y(x); // Found by both unqualified lookup and ADL, doesn't match

[EricWF]

Address final review comments.

include/clang/AST/Expr.h

   SourceLocation RParenLoc;
 
   void updateDependenciesFromArg(Expr *Arg);
 
 protected:
   // These versions of the constructor are for derived classes.
   CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
            ArrayRef<Expr *> preargs, ArrayRef<Expr *> args, QualType t,
-           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0);
+           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0,
+           bool UsesADL = false);
   CallExpr(const ASTContext &C, StmtClass SC, Expr *fn, ArrayRef<Expr *> args,
            QualType t, ExprValueKind VK, SourceLocation rparenloc,
-           unsigned MinNumArgs = 0);
+           unsigned MinNumArgs = 0, bool UsesADL = false);
   CallExpr(const ASTContext &C, StmtClass SC, unsigned NumPreArgs,
-           unsigned NumArgs, EmptyShell Empty);
+           unsigned NumArgs, bool UsesADL, EmptyShell Empty);
 
   Stmt *getPreArg(unsigned i) {
     assert(i < getNumPreArgs() && "Prearg access out of range!");
     return SubExprs[PREARGS_START+i];
   }
   const Stmt *getPreArg(unsigned i) const {
     assert(i < getNumPreArgs() && "Prearg access out of range!");
     return SubExprs[PREARGS_START+i];
   }
   void setPreArg(unsigned i, Stmt *PreArg) {
     assert(i < getNumPreArgs() && "Prearg access out of range!");
     SubExprs[PREARGS_START+i] = PreArg;
   }
 
   unsigned getNumPreArgs() const { return CallExprBits.NumPreArgs; }
 
 public:
   /// Build a call expression. MinNumArgs specifies the minimum number of
   /// arguments. The actual number of arguments will be the greater of
   /// args.size() and MinNumArgs.
   CallExpr(const ASTContext &C, Expr *fn, ArrayRef<Expr *> args, QualType t,
-           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0);
+           ExprValueKind VK, SourceLocation rparenloc, unsigned MinNumArgs = 0,
+           bool UsesADL = false);
 
   /// Build an empty call expression.
   CallExpr(const ASTContext &C, unsigned NumArgs, EmptyShell Empty);
 
   const Expr *getCallee() const { return cast<Expr>(SubExprs[FN]); }
   Expr *getCallee() { return cast<Expr>(SubExprs[FN]); }
   void setCallee(Expr *F) { SubExprs[FN] = F; }
 
+  bool usesADL() const { return CallExprBits.UsesADL; }
+  void setUsesADL(bool V = true) { CallExprBits.UsesADL = V; }
+
   Decl *getCalleeDecl();
   const Decl *getCalleeDecl() const {
     return const_cast<CallExpr*>(this)->getCalleeDecl();
   }
 
   /// If the callee is a FunctionDecl, return it. Otherwise return 0.
   FunctionDecl *getDirectCallee();
   const FunctionDecl *getDirectCallee() const {

include/clang/AST/ExprCXX.h

class CXXOperatorCallExpr : public CallExpr {
   FPOptions FPFeatures;
 
   SourceRange getSourceRangeImpl() const LLVM_READONLY;
 
 public:
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
 
-  CXXOperatorCallExpr(ASTContext& C, OverloadedOperatorKind Op, Expr *fn,
-                      ArrayRef<Expr*> args, QualType t, ExprValueKind VK,
-                      SourceLocation operatorloc, FPOptions FPFeatures)
-      : CallExpr(C, CXXOperatorCallExprClass, fn, args, t, VK, operatorloc),
+  CXXOperatorCallExpr(ASTContext &C, OverloadedOperatorKind Op, Expr *fn,
+                      ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
+                      SourceLocation operatorloc, FPOptions FPFeatures,
+                      bool UsesADL = false)
+      : CallExpr(C, CXXOperatorCallExprClass, fn, args, t, VK, operatorloc,
+                 /*MinNumArgs=*/0, UsesADL),
         Operator(Op), FPFeatures(FPFeatures) {
     Range = getSourceRangeImpl();
   }
 
   explicit CXXOperatorCallExpr(ASTContext &C, unsigned NumArgs,
                                EmptyShell Empty)
       : CallExpr(C, CXXOperatorCallExprClass, /*NumPreArgs=*/0, NumArgs,
-                 Empty) {}
+                 /*UsesADL=*/false, Empty) {}
 
   /// Returns the kind of overloaded operator that this
   /// expression refers to.
   OverloadedOperatorKind getOperator() const { return Operator; }
 
   static bool isAssignmentOp(OverloadedOperatorKind Opc) {
     return Opc == OO_Equal || Opc == OO_StarEqual ||
            Opc == OO_SlashEqual || Opc == OO_PercentEqual ||

 /// both the object argument and the member function, while the
 /// arguments are the arguments within the parentheses (not including
 /// the object argument).
 class CXXMemberCallExpr : public CallExpr {
 public:
   CXXMemberCallExpr(ASTContext &C, Expr *fn, ArrayRef<Expr *> args, QualType t,
                     ExprValueKind VK, SourceLocation RP,
                     unsigned MinNumArgs = 0)
-      : CallExpr(C, CXXMemberCallExprClass, fn, args, t, VK, RP, MinNumArgs) {}
+      : CallExpr(C, CXXMemberCallExprClass, fn, args, t, VK, RP, MinNumArgs,
+                 /*UsesADL=*/false) {}
 
   CXXMemberCallExpr(ASTContext &C, unsigned NumArgs, EmptyShell Empty)
-      : CallExpr(C, CXXMemberCallExprClass, /*NumPreArgs=*/0, NumArgs, Empty) {}
+      : CallExpr(C, CXXMemberCallExprClass, /*NumPreArgs=*/0, NumArgs,
+                 /*UsesADL=*/false, Empty) {}
 
   /// Retrieves the implicit object argument for the member call.
   ///
   /// For example, in "x.f(5)", this returns the sub-expression "x".
   Expr *getImplicitObjectArgument() const;
 
   /// Retrieves the declaration of the called method.
   CXXMethodDecl *getMethodDecl() const;

 /// Represents a call to a CUDA kernel function.
 class CUDAKernelCallExpr : public CallExpr {
 private:
   enum { CONFIG, END_PREARG };
 
 public:
   CUDAKernelCallExpr(ASTContext &C, Expr *fn, CallExpr *Config,
                      ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
-                     SourceLocation RP, unsigned MinNumArgs = 0)
+                     SourceLocation RP, unsigned MinNumArgs = 0,
+                     bool UsesADL = false)
       : CallExpr(C, CUDAKernelCallExprClass, fn, Config, args, t, VK, RP,
-                 MinNumArgs) {}
+                 MinNumArgs, UsesADL) {}
 
   CUDAKernelCallExpr(ASTContext &C, unsigned NumArgs, EmptyShell Empty)
       : CallExpr(C, CUDAKernelCallExprClass, /*NumPreArgs=*/END_PREARG, NumArgs,
-                 Empty) {}
+                 /*UsesADL=*/false, Empty) {}
 
   const CallExpr *getConfig() const {
     return cast_or_null<CallExpr>(getPreArg(CONFIG));
   }
   CallExpr *getConfig() { return cast_or_null<CallExpr>(getPreArg(CONFIG)); }
 
   /// Sets the kernel configuration expression.
   ///

 class UserDefinedLiteral : public CallExpr {
   /// The location of a ud-suffix within the literal.
   SourceLocation UDSuffixLoc;
 
 public:
   friend class ASTStmtReader;
   friend class ASTStmtWriter;
 
-  UserDefinedLiteral(const ASTContext &C, Expr *Fn, ArrayRef<Expr*> Args,
+  UserDefinedLiteral(const ASTContext &C, Expr *Fn, ArrayRef<Expr *> Args,
                      QualType T, ExprValueKind VK, SourceLocation LitEndLoc,
                      SourceLocation SuffixLoc)
-      : CallExpr(C, UserDefinedLiteralClass, Fn, Args, T, VK, LitEndLoc),
+      : CallExpr(C, UserDefinedLiteralClass, Fn, Args, T, VK, LitEndLoc,
+                 /*MinNumArgs=*/0, /*UsesADL=*/false),
         UDSuffixLoc(SuffixLoc) {}
 
   explicit UserDefinedLiteral(const ASTContext &C, unsigned NumArgs,
                               EmptyShell Empty)
       : CallExpr(C, UserDefinedLiteralClass, /*NumPreArgs=*/0, NumArgs,
-                 Empty) {}
+                 /*UsesADL=*/false, Empty) {}
 
   /// The kind of literal operator which is invoked.
   enum LiteralOperatorKind {
     /// Raw form: operator "" X (const char *)
     LOK_Raw,
 
     /// Raw form: operator "" X<cs...> ()
     LOK_Template,

include/clang/AST/Stmt.h

protected:
   };
 
   class CallExprBitfields {
     friend class CallExpr;
 
     unsigned : NumExprBits;
 
     unsigned NumPreArgs : 1;
+
+    /// True if the callee of the call expression was found using ADL.
+    unsigned UsesADL : 1;
   };
 
   class MemberExprBitfields {
     friend class MemberExpr;
 
     unsigned : NumExprBits;
 
     /// IsArrow - True if this is "X->F", false if this is "X.F".

include/clang/ASTMatchers/ASTMatchers.h

 /// Example matches x.y() and y()
 /// \code
 ///   X x;
 ///   x.y();
 ///   y();
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, CallExpr> callExpr;
 
+/// Matches call expressions which were resolved using ADL.
+///
+/// Example matches y(x) but not y(42) or NS::y(x).
+/// \code
+///   namespace NS {
+///     struct X {};
+///     void y(X);
+///   } // namespace NS
+///
+///   void y(...);
+///
+///   void test() {
+///     NS::X x;
+///     y(x); // Matches
+///     NS::y(x); // Doesn't match
+///     y(42);
+///   }
+/// \endcode
+AST_MATCHER(CallExpr, usesADL) { return Node.usesADL(); }
+
 /// Matches lambda expressions.
 ///
 /// Example matches [&](){return 5;}
 /// \code
 ///   [&](){return 5;}
 /// \endcode
 extern const internal::VariadicDynCastAllOfMatcher<Stmt, LambdaExpr> lambdaExpr;
 

include/clang/Sema/Overload.h

struct OverloadCandidate {
     /// argument's conversion, which for this function represents the
     /// implicit object argument, should be ignored. This will be true
     /// when the candidate is a static member function (where the
     /// implicit object argument is just a placeholder) or a
     /// non-static member function when the call doesn't have an
     /// object argument.
     bool IgnoreObjectArgument;
 
+    /// True if the candidate was found using ADL.
+    bool IsADLCandidate;
+
     /// FailureKind - The reason why this candidate is not viable.
     /// Actually an OverloadFailureKind.
     unsigned char FailureKind;
 
     /// The number of call arguments that were explicitly provided,
     /// to be used while performing partial ordering of function templates.
     unsigned ExplicitCallArguments;
 
unsigned getNumParams() const {
         while (STy->isPointerType() || STy->isReferenceType())
           STy = STy->getPointeeType();
         return STy->getAs<FunctionProtoType>()->getNumParams();
       }
       if (Function)
         return Function->getNumParams();
       return ExplicitCallArguments;
     }
+
+  private:
+    // Only the OverloadCandidate set is allowed to construct OverloadCandidates.
+    friend class OverloadCandidateSet;
+    OverloadCandidate() = default;
   };
 
   /// OverloadCandidateSet - A set of overload candidates, used in C++
   /// overload resolution (C++ 13.3).
   class OverloadCandidateSet {
   public:
     enum CandidateSetKind {
       /// Normal lookup.
public:
     /// to the overload set.
     OverloadCandidate &addCandidate(unsigned NumConversions = 0,
                                     ConversionSequenceList Conversions = None) {
       assert((Conversions.empty() || Conversions.size() == NumConversions) &&
              "preallocated conversion sequence has wrong length");
 
       Candidates.push_back(OverloadCandidate());
       OverloadCandidate &C = Candidates.back();
+      C.IsADLCandidate = false;
       C.Conversions = Conversions.empty()
                           ? allocateConversionSequences(NumConversions)
                           : Conversions;
       return C;
     }
 
     /// Find the best viable function on this overload set, if it exists.
     OverloadingResult BestViableFunction(Sema &S, SourceLocation Loc,

include/clang/Sema/Sema.h

                                            NamedDecl *FoundDecl,
                                            NamedDecl *Member);
 
   // Members have to be NamespaceDecl* or TranslationUnitDecl*.
   // TODO: make this is a typesafe union.
   typedef llvm::SmallSetVector<DeclContext   *, 16> AssociatedNamespaceSet;
   typedef llvm::SmallSetVector<CXXRecordDecl *, 16> AssociatedClassSet;
 
-  void AddOverloadCandidate(FunctionDecl *Function,
-                            DeclAccessPair FoundDecl,
+  void AddOverloadCandidate(FunctionDecl *Function, DeclAccessPair FoundDecl,
                             ArrayRef<Expr *> Args,
                             OverloadCandidateSet &CandidateSet,
                             bool SuppressUserConversions = false,
                             bool PartialOverloading = false,
                             bool AllowExplicit = false,
+                            bool IsADLCandidate = false,
                             ConversionSequenceList EarlyConversions = None);
   void AddFunctionCandidates(const UnresolvedSetImpl &Functions,
                       ArrayRef<Expr *> Args,
                       OverloadCandidateSet &CandidateSet,
                       TemplateArgumentListInfo *ExplicitTemplateArgs = nullptr,
                       bool SuppressUserConversions = false,
                       bool PartialOverloading = false,
                       bool FirstArgumentIsBase = false);

                                   CXXRecordDecl *ActingContext,
                                  TemplateArgumentListInfo *ExplicitTemplateArgs,
                                   QualType ObjectType,
                                   Expr::Classification ObjectClassification,
                                   ArrayRef<Expr *> Args,
                                   OverloadCandidateSet& CandidateSet,
                                   bool SuppressUserConversions = false,
                                   bool PartialOverloading = false);
-  void AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
-                                    DeclAccessPair FoundDecl,
-                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
-                                    ArrayRef<Expr *> Args,
-                                    OverloadCandidateSet& CandidateSet,
-                                    bool SuppressUserConversions = false,
-                                    bool PartialOverloading = false);
+  void AddTemplateOverloadCandidate(
+      FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
+      TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
+      OverloadCandidateSet &CandidateSet, bool SuppressUserConversions = false,
+      bool PartialOverloading = false, bool IsADLCandidate = false);
   bool CheckNonDependentConversions(FunctionTemplateDecl *FunctionTemplate,
                                     ArrayRef<QualType> ParamTypes,
                                     ArrayRef<Expr *> Args,
                                     OverloadCandidateSet &CandidateSet,
                                     ConversionSequenceList &Conversions,
                                     bool SuppressUserConversions,
                                     CXXRecordDecl *ActingContext = nullptr,
                                     QualType ObjectType = QualType(),

 
   /// ActOnCallExpr - Handle a call to Fn with the specified array of arguments.
   /// This provides the location of the left/right parens and a list of comma
   /// locations.
   ExprResult ActOnCallExpr(Scope *S, Expr *Fn, SourceLocation LParenLoc,
                            MultiExprArg ArgExprs, SourceLocation RParenLoc,
                            Expr *ExecConfig = nullptr,
                            bool IsExecConfig = false);
-  ExprResult BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
-                                   SourceLocation LParenLoc,
-                                   ArrayRef<Expr *> Arg,
-                                   SourceLocation RParenLoc,
-                                   Expr *Config = nullptr,
-                                   bool IsExecConfig = false);
+  ExprResult
+  BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl, SourceLocation LParenLoc,
+                        ArrayRef<Expr *> Arg, SourceLocation RParenLoc,
+                        Expr *Config = nullptr, bool IsExecConfig = false,
+                        bool UsesADL = false);
 
   ExprResult ActOnCUDAExecConfigExpr(Scope *S, SourceLocation LLLLoc,
                                      MultiExprArg ExecConfig,
                                      SourceLocation GGGLoc);
 
   ExprResult ActOnCastExpr(Scope *S, SourceLocation LParenLoc,
                            Declarator &D, ParsedType &Ty,
                            SourceLocation RParenLoc, Expr *CastExpr);

lib/AST/ASTDumper.cpp

public:
     void VisitCXXCatchStmt(const CXXCatchStmt *Node);
     void VisitCaseStmt(const CaseStmt *Node);
     void VisitCapturedStmt(const CapturedStmt *Node);
 
     // OpenMP
     void VisitOMPExecutableDirective(const OMPExecutableDirective *Node);
 
     // Exprs
+    void VisitCallExpr(const CallExpr *Node);
     void VisitCastExpr(const CastExpr *Node);
     void VisitImplicitCastExpr(const ImplicitCastExpr *Node);
     void VisitDeclRefExpr(const DeclRefExpr *Node);
     void VisitPredefinedExpr(const PredefinedExpr *Node);
     void VisitCharacterLiteral(const CharacterLiteral *Node);
     void VisitIntegerLiteral(const IntegerLiteral *Node);
     void VisitFixedPointLiteral(const FixedPointLiteral *Node);
     void VisitFloatingLiteral(const FloatingLiteral *Node);
if (Base->isVirtual())
       OS << "virtual ";
     OS << RD->getName();
     First = false;
   }
 
   OS << ')';
 }
 
+void ASTDumper::VisitCallExpr(const CallExpr *Node) {
+  if (Node->usesADL())
+    OS << " adl";
+}
+
 void ASTDumper::VisitCastExpr(const CastExpr *Node) {
   OS << " <";
   {
     ColorScope Color(OS, ShowColors, CastColor);
     OS << Node->getCastKindName();
   }
   dumpBasePath(OS, Node);
   OS << ">";

lib/AST/ASTImporter.cpp

   unsigned NumArgs = E->getNumArgs();
   llvm::SmallVector<Expr *, 2> ToArgs(NumArgs);
   if (Error Err = ImportContainerChecked(E->arguments(), ToArgs))
      return std::move(Err);
 
   if (const auto *OCE = dyn_cast<CXXOperatorCallExpr>(E)) {
     return new (Importer.getToContext()) CXXOperatorCallExpr(
         Importer.getToContext(), OCE->getOperator(), ToCallee, ToArgs, ToType,
-        OCE->getValueKind(), ToRParenLoc, OCE->getFPFeatures());
+        OCE->getValueKind(), ToRParenLoc, OCE->getFPFeatures(), OCE->usesADL());
   }
 
   return new (Importer.getToContext()) CallExpr(
       Importer.getToContext(), ToCallee, ToArgs, ToType, E->getValueKind(),
       ToRParenLoc);
 }
 
 ExpectedStmt ASTNodeImporter::VisitLambdaExpr(LambdaExpr *E) {
   CXXRecordDecl *FromClass = E->getLambdaClass();
   auto ToClassOrErr = import(FromClass);
   if (!ToClassOrErr)
     return ToClassOrErr.takeError();

lib/AST/Expr.cpp

 
 //===----------------------------------------------------------------------===//
 // Postfix Operators.
 //===----------------------------------------------------------------------===//
 
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
                    ArrayRef<Expr *> preargs, ArrayRef<Expr *> args, QualType t,
                    ExprValueKind VK, SourceLocation rparenloc,
-                   unsigned MinNumArgs)
+                   unsigned MinNumArgs, bool UsesADL)
     : Expr(SC, t, VK, OK_Ordinary, fn->isTypeDependent(),
            fn->isValueDependent(), fn->isInstantiationDependent(),
            fn->containsUnexpandedParameterPack()),
       RParenLoc(rparenloc) {
+  CallExprBits.UsesADL = UsesADL;
+
   NumArgs = std::max<unsigned>(args.size(), MinNumArgs);
   unsigned NumPreArgs = preargs.size();
   CallExprBits.NumPreArgs = NumPreArgs;
 
   SubExprs = new (C) Stmt *[NumArgs + PREARGS_START + NumPreArgs];
   SubExprs[FN] = fn;
   for (unsigned i = 0; i != NumPreArgs; ++i) {
     updateDependenciesFromArg(preargs[i]);
     SubExprs[i+PREARGS_START] = preargs[i];
   }
   for (unsigned i = 0; i != args.size(); ++i) {
     updateDependenciesFromArg(args[i]);
     SubExprs[i+PREARGS_START+NumPreArgs] = args[i];
   }
   for (unsigned i = args.size(); i != NumArgs; ++i) {
     SubExprs[i + PREARGS_START + NumPreArgs] = nullptr;
   }
 }
 
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, Expr *fn,
                    ArrayRef<Expr *> args, QualType t, ExprValueKind VK,
-                   SourceLocation rparenloc, unsigned MinNumArgs)
+                   SourceLocation rparenloc, unsigned MinNumArgs, bool UsesADL)
     : CallExpr(C, SC, fn, ArrayRef<Expr *>(), args, t, VK, rparenloc,
-               MinNumArgs) {}
+               MinNumArgs, UsesADL) {}
 
 CallExpr::CallExpr(const ASTContext &C, Expr *fn, ArrayRef<Expr *> args,
                    QualType t, ExprValueKind VK, SourceLocation rparenloc,
-                   unsigned MinNumArgs)
-    : CallExpr(C, CallExprClass, fn, ArrayRef<Expr *>(), args, t, VK,
-               rparenloc, MinNumArgs) {}
+                   unsigned MinNumArgs, bool UsesADL)
+    : CallExpr(C, CallExprClass, fn, ArrayRef<Expr *>(), args, t, VK, rparenloc,
+               MinNumArgs, UsesADL) {}
 
 CallExpr::CallExpr(const ASTContext &C, StmtClass SC, unsigned NumPreArgs,
-                   unsigned NumArgs, EmptyShell Empty)
+                   unsigned NumArgs, bool UsesADL, EmptyShell Empty)
     : Expr(SC, Empty), NumArgs(NumArgs) {
+  CallExprBits.UsesADL = UsesADL;
   CallExprBits.NumPreArgs = NumPreArgs;
   SubExprs = new (C) Stmt *[NumArgs + PREARGS_START + NumPreArgs];
 }
 
 CallExpr::CallExpr(const ASTContext &C, unsigned NumArgs, EmptyShell Empty)
-    : CallExpr(C, CallExprClass, /*NumPreArgs=*/0, NumArgs, Empty) {}
+    : CallExpr(C, CallExprClass, /*NumPreArgs=*/0, NumArgs, /*UsesADL=*/false,
+               Empty) {}
 
 void CallExpr::updateDependenciesFromArg(Expr *Arg) {
   if (Arg->isTypeDependent())
     ExprBits.TypeDependent = true;
   if (Arg->isValueDependent())
     ExprBits.ValueDependent = true;
   if (Arg->isInstantiationDependent())
     ExprBits.InstantiationDependent = true;

lib/Sema/SemaExpr.cpp

 }
 
 /// BuildResolvedCallExpr - Build a call to a resolved expression,
 /// i.e. an expression not of \p OverloadTy.  The expression should
 /// unary-convert to an expression of function-pointer or
 /// block-pointer type.
 ///
 /// \param NDecl the declaration being called, if available
-ExprResult
-Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
-                            SourceLocation LParenLoc,
-                            ArrayRef<Expr *> Args,
-                            SourceLocation RParenLoc,
-                            Expr *Config, bool IsExecConfig) {
+ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
+                                       SourceLocation LParenLoc,
+                                       ArrayRef<Expr *> Args,
+                                       SourceLocation RParenLoc, Expr *Config,
+                                       bool IsExecConfig, bool UsesADL) {
   FunctionDecl *FDecl = dyn_cast_or_null<FunctionDecl>(NDecl);
   unsigned BuiltinID = (FDecl ? FDecl->getBuiltinID() : 0);
 
   // Functions with 'interrupt' attribute cannot be called directly.
   if (FDecl && FDecl->hasAttr<AnyX86InterruptAttr>()) {
     Diag(Fn->getExprLoc(), diag::err_anyx86_interrupt_called);
     return ExprError();
   }

 
   // Get the number of parameters in the function prototype, if any.
   // We will allocate space for max(Args.size(), NumParams) arguments
   // in the call expression.
   const auto *Proto = dyn_cast_or_null<FunctionProtoType>(FuncT);
   unsigned NumParams = Proto ? Proto->getNumParams() : 0;
 
   CallExpr *TheCall;
   if (Config)
     TheCall = new (Context)
         CUDAKernelCallExpr(Context, Fn, cast<CallExpr>(Config), Args, ResultTy,
-                           VK_RValue, RParenLoc, NumParams);
+                           VK_RValue, RParenLoc, NumParams, UsesADL);
   else
-    TheCall = new (Context)
-        CallExpr(Context, Fn, Args, ResultTy, VK_RValue, RParenLoc, NumParams);
+    TheCall = new (Context) CallExpr(Context, Fn, Args, ResultTy, VK_RValue,
+                                     RParenLoc, NumParams, UsesADL);
 
   if (!getLangOpts().CPlusPlus) {
     // C cannot always handle TypoExpr nodes in builtin calls and direct
     // function calls as their argument checking don't necessarily handle
     // dependent types properly, so make sure any TypoExprs have been
     // dealt with.
     ExprResult Result = CorrectDelayedTyposInExpr(TheCall);
     if (!Result.isUsable()) return ExprError();

lib/Sema/SemaOverload.cpp

 /// AddOverloadCandidate - Adds the given function to the set of
 /// candidate functions, using the given function call arguments.  If
 /// @p SuppressUserConversions, then don't allow user-defined
 /// conversions via constructors or conversion operators.
 ///
 /// \param PartialOverloading true if we are performing "partial" overloading
 /// based on an incomplete set of function arguments. This feature is used by
 /// code completion.
-void
-Sema::AddOverloadCandidate(FunctionDecl *Function,
-                           DeclAccessPair FoundDecl,
-                           ArrayRef<Expr *> Args,
-                           OverloadCandidateSet &CandidateSet,
-                           bool SuppressUserConversions,
-                           bool PartialOverloading,
-                           bool AllowExplicit,
-                           ConversionSequenceList EarlyConversions) {
+void Sema::AddOverloadCandidate(FunctionDecl *Function,
+                                DeclAccessPair FoundDecl, ArrayRef<Expr *> Args,
+                                OverloadCandidateSet &CandidateSet,
+                                bool SuppressUserConversions,
+                                bool PartialOverloading, bool AllowExplicit,
+                                bool IsADLCandidate,
+                                ConversionSequenceList EarlyConversions) {
   const FunctionProtoType *Proto
     = dyn_cast<FunctionProtoType>(Function->getType()->getAs<FunctionType>());
   assert(Proto && "Functions without a prototype cannot be overloaded");
   assert(!Function->getDescribedFunctionTemplate() &&
          "Use AddTemplateOverloadCandidate for function templates");
 
   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Function)) {
     if (!isa<CXXConstructorDecl>(Method)) {

 
   // Add this candidate
   OverloadCandidate &Candidate =
       CandidateSet.addCandidate(Args.size(), EarlyConversions);
   Candidate.FoundDecl = FoundDecl;
   Candidate.Function = Function;
   Candidate.Viable = true;
   Candidate.IsSurrogate = false;
+  Candidate.IsADLCandidate = IsADLCandidate;
   Candidate.IgnoreObjectArgument = false;
   Candidate.ExplicitCallArguments = Args.size();
 
   if (Function->isMultiVersion() && Function->hasAttr<TargetAttr>() &&
       !Function->getAttr<TargetAttr>()->isDefaultVersion()) {
     Candidate.Viable = false;
     Candidate.FailureKind = ovl_non_default_multiversion_function;
     return;

                      ActingContext, ObjectType, ObjectClassification, Args,
                      CandidateSet, SuppressUserConversions, PartialOverloading,
                      Conversions);
 }
 
 /// Add a C++ function template specialization as a candidate
 /// in the candidate set, using template argument deduction to produce
 /// an appropriate function template specialization.
-void
-Sema::AddTemplateOverloadCandidate(FunctionTemplateDecl *FunctionTemplate,
-                                   DeclAccessPair FoundDecl,
-                                 TemplateArgumentListInfo *ExplicitTemplateArgs,
-                                   ArrayRef<Expr *> Args,
-                                   OverloadCandidateSet& CandidateSet,
-                                   bool SuppressUserConversions,
-                                   bool PartialOverloading) {
+void Sema::AddTemplateOverloadCandidate(
+    FunctionTemplateDecl *FunctionTemplate, DeclAccessPair FoundDecl,
+    TemplateArgumentListInfo *ExplicitTemplateArgs, ArrayRef<Expr *> Args,
+    OverloadCandidateSet &CandidateSet, bool SuppressUserConversions,
+    bool PartialOverloading, bool IsADLCandidate) {
   if (!CandidateSet.isNewCandidate(FunctionTemplate))
     return;
 
   // C++ [over.match.funcs]p7:
   //   In each case where a candidate is a function template, candidate
   //   function template specializations are generated using template argument
   //   deduction (14.8.3, 14.8.2). Those candidates are then handled as
   //   candidate functions in the usual way.113) A given name can refer to one

                                                 SuppressUserConversions);
           })) {
     OverloadCandidate &Candidate =
         CandidateSet.addCandidate(Conversions.size(), Conversions);
     Candidate.FoundDecl = FoundDecl;
     Candidate.Function = FunctionTemplate->getTemplatedDecl();
     Candidate.Viable = false;
     Candidate.IsSurrogate = false;
+    Candidate.IsADLCandidate = IsADLCandidate;
     // Ignore the object argument if there is one, since we don't have an object
     // type.
     Candidate.IgnoreObjectArgument =
         isa<CXXMethodDecl>(Candidate.Function) &&
         !isa<CXXConstructorDecl>(Candidate.Function);
     Candidate.ExplicitCallArguments = Args.size();
     if (Result == TDK_NonDependentConversionFailure)
       Candidate.FailureKind = ovl_fail_bad_conversion;
     else {
       Candidate.FailureKind = ovl_fail_bad_deduction;
       Candidate.DeductionFailure = MakeDeductionFailureInfo(Context, Result,
                                                             Info);
     }
     return;
   }
 
   // Add the function template specialization produced by template argument
   // deduction as a candidate.
   assert(Specialization && "Missing function template specialization?");
   AddOverloadCandidate(Specialization, FoundDecl, Args, CandidateSet,
                        SuppressUserConversions, PartialOverloading,
-                       /*AllowExplicit*/false, Conversions);
+                       /*AllowExplicit*/ false, IsADLCandidate, Conversions);
 }
 
 /// Check that implicit conversion sequences can be formed for each argument
 /// whose corresponding parameter has a non-dependent type, per DR1391's
 /// [temp.deduct.call]p10.
 bool Sema::CheckNonDependentConversions(
     FunctionTemplateDecl *FunctionTemplate, ArrayRef<QualType> ParamTypes,
     ArrayRef<Expr *> Args, OverloadCandidateSet &CandidateSet,

       if (FunctionTemplateDecl *FunTmpl = Cand->Function->getPrimaryTemplate())
         Fns.erase(FunTmpl);
     }
 
   // For each of the ADL candidates we found, add it to the overload
   // set.
   for (ADLResult::iterator I = Fns.begin(), E = Fns.end(); I != E; ++I) {
     DeclAccessPair FoundDecl = DeclAccessPair::make(*I, AS_none);
+
     if (FunctionDecl *FD = dyn_cast<FunctionDecl>(*I)) {
       if (ExplicitTemplateArgs)
         continue;
 
       AddOverloadCandidate(FD, FoundDecl, Args, CandidateSet, false,
-                           PartialOverloading);
+                           PartialOverloading, /*AllowExplicit=*/false,
+                           /*IsADLCandidate=*/true);
     } else
-      AddTemplateOverloadCandidate(cast<FunctionTemplateDecl>(*I),
-                                   FoundDecl, ExplicitTemplateArgs,
-                                   Args, CandidateSet, PartialOverloading);
+      AddTemplateOverloadCandidate(cast<FunctionTemplateDecl>(*I), FoundDecl,
+                                   ExplicitTemplateArgs, Args, CandidateSet,
+                                   /*SuppressUserConversions=*/false,
+                                   PartialOverloading, /*IsADLCandidate=*/true);
   }
 }
 
 namespace {
 enum class Comparison { Equal, Better, Worse };
 }
 
 /// Compares the enable_if attributes of two FunctionDecls, for the purposes of

   switch (OverloadResult) {
   case OR_Success: {
     FunctionDecl *FDecl = (*Best)->Function;
     SemaRef.CheckUnresolvedLookupAccess(ULE, (*Best)->FoundDecl);
     if (SemaRef.DiagnoseUseOfDecl(FDecl, ULE->getNameLoc()))
       return ExprError();
     Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
     return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
-                                         ExecConfig);
+                                         ExecConfig, /*IsExecConfig*/ false,
+                                         (*Best)->IsADLCandidate);
   }
 
   case OR_No_Viable_Function: {
     // Try to recover by looking for viable functions which the user might
     // have meant to call.
     ExprResult Recovery = BuildRecoveryCallExpr(SemaRef, S, Fn, ULE, LParenLoc,
                                                 Args, RParenLoc,
                                                 /*EmptyLookup=*/false,

         << Fn->getSourceRange();
     CandidateSet->NoteCandidates(SemaRef, OCD_AllCandidates, Args);
 
     // We emitted an error for the unavailable/deleted function call but keep
     // the call in the AST.
     FunctionDecl *FDecl = (*Best)->Function;
     Fn = SemaRef.FixOverloadedFunctionReference(Fn, (*Best)->FoundDecl, FDecl);
     return SemaRef.BuildResolvedCallExpr(Fn, FDecl, LParenLoc, Args, RParenLoc,
-                                         ExecConfig);
+                                         ExecConfig, /*IsExecConfig*/ false,
+                                         (*Best)->IsADLCandidate);
   }
   }
 
   // Overload resolution failed.
   return ExprError();
 }
 
 static void markUnaddressableCandidatesUnviable(Sema &S,

         return ExprError();
 
       // Determine the result type.
       QualType ResultTy = FnDecl->getReturnType();
       ExprValueKind VK = Expr::getValueKindForType(ResultTy);
       ResultTy = ResultTy.getNonLValueExprType(Context);
 
       Args[0] = Input;
-      CallExpr *TheCall =
-        new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(), ArgsArray,
-                                          ResultTy, VK, OpLoc, FPOptions());
+      CallExpr *TheCall = new (Context)
+          CXXOperatorCallExpr(Context, Op, FnExpr.get(), ArgsArray, ResultTy,
+                              VK, OpLoc, FPOptions(), Best->IsADLCandidate);
 
       if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall, FnDecl))
         return ExprError();
 
       if (CheckFunctionCall(FnDecl, TheCall,
                             FnDecl->getType()->castAs<FunctionProtoType>()))
         return ExprError();
 

         if (FnExpr.isInvalid())
           return ExprError();
 
         // Determine the result type.
         QualType ResultTy = FnDecl->getReturnType();
         ExprValueKind VK = Expr::getValueKindForType(ResultTy);
         ResultTy = ResultTy.getNonLValueExprType(Context);
 
-        CXXOperatorCallExpr *TheCall =
-          new (Context) CXXOperatorCallExpr(Context, Op, FnExpr.get(),
-                                            Args, ResultTy, VK, OpLoc,
-                                            FPFeatures);
+        CXXOperatorCallExpr *TheCall = new (Context)
+            CXXOperatorCallExpr(Context, Op, FnExpr.get(), Args, ResultTy, VK,
+                                OpLoc, FPFeatures, Best->IsADLCandidate);
 
         if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall,
                                 FnDecl))
           return ExprError();
 
         ArrayRef<const Expr *> ArgsArray(Args, 2);
         const Expr *ImplicitThis = nullptr;
         // Cut off the implicit 'this'.

lib/Serialization/ASTReaderStmt.cpp

void ASTStmtReader::VisitOMPArraySectionExpr(OMPArraySectionExpr *E) {
   E->setLength(Record.readSubExpr());
   E->setColonLoc(ReadSourceLocation());
   E->setRBracketLoc(ReadSourceLocation());
 }
 
 void ASTStmtReader::VisitCallExpr(CallExpr *E) {
   VisitExpr(E);
   unsigned NumArgs = Record.readInt();
+  bool UsesADL = Record.readInt();
   assert((NumArgs == E->getNumArgs()) && "Wrong NumArgs!");
   E->setRParenLoc(ReadSourceLocation());
   E->setCallee(Record.readSubExpr());
   for (unsigned I = 0; I != NumArgs; ++I)
     E->setArg(I, Record.readSubExpr());
+  E->setUsesADL(UsesADL);
 }
 
 void ASTStmtReader::VisitCXXMemberCallExpr(CXXMemberCallExpr *E) {
   VisitCallExpr(E);
 }
 
 void ASTStmtReader::VisitMemberExpr(MemberExpr *E) {
   // Don't call VisitExpr, this is fully initialized at creation.

lib/Serialization/ASTWriterStmt.cpp

void ASTStmtWriter::VisitOMPArraySectionExpr(OMPArraySectionExpr *E) {
   Record.AddSourceLocation(E->getColonLoc());
   Record.AddSourceLocation(E->getRBracketLoc());
   Code = serialization::EXPR_OMP_ARRAY_SECTION;
 }
 
 void ASTStmtWriter::VisitCallExpr(CallExpr *E) {
   VisitExpr(E);
   Record.push_back(E->getNumArgs());
+  Record.push_back(E->usesADL());
   Record.AddSourceLocation(E->getRParenLoc());
   Record.AddStmt(E->getCallee());
   for (CallExpr::arg_iterator Arg = E->arg_begin(), ArgEnd = E->arg_end();
        Arg != ArgEnd; ++Arg)
     Record.AddStmt(*Arg);
   Code = serialization::EXPR_CALL;
 }
 

test/AST/ast-dump-expr.cpp

+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=c++14 -ast-dump %s \
+// RUN:    | FileCheck -strict-whitespace %s
+
+namespace NS {
+struct X {};
+void f(X);
+void y(...);
+} // namespace NS
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}ADLCall 'void ()'
+void ADLCall() {
+  NS::X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  f(x);
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  y(x);
+}
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall 'void ()'
+void NonADLCall() {
+  NS::X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  NS::f(x);
+}
+
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall2 'void ()'
+void NonADLCall2() {
+  NS::X x;
+  using NS::f;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  f(x);
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void' adl{{$}}
+  y(x);
+}
+
+namespace test_adl_call_three {
+using namespace NS;
+// CHECK-LABEL: FunctionDecl 0x{{[^ ]*}} {{.*}}NonADLCall3 'void ()'
+void NonADLCall3() {
+  X x;
+  // CHECK: CallExpr 0x{{[^ ]*}} <line:[[@LINE+1]]:{{[^>]+}}> 'void'{{$}}
+  f(x);
+}
+} // namespace test_adl_call_three

unittests/ASTMatchers/ASTMatchersNodeTest.cpp

EXPECT_TRUE(matchesConditionally("template<typename T>"
                                    "void bar() {"
                                    "  foo<T>();"
                                    "}",
                                    unresolvedLookupExpr(),
                                    /*ExpectMatch=*/true,
                                    "-fno-delayed-template-parsing"));
 }
 
+TEST(Matcher, ADLCall) {
+  StatementMatcher ADLMatch = callExpr(usesADL());
+  auto NS_Str = R"DELIM(
+  namespace NS {
+    struct X {};
+    struct Y {};
+    void f(X);
+    template <class T>
+    void g(T);
+  }
+  struct MyX {};
+  void f(...);
+  void g(...);
+)DELIM";
+
+  auto MkStr = [&](std::string Body) -> std::string {
+    std::string S = NS_Str;
+    S += "void test_fn() { " + Body + " }";
+    return S;
+  };
+
+  EXPECT_TRUE(matches(MkStr("NS::X x; f(x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("NS::X x; NS::f(x);"), ADLMatch));
+  EXPECT_TRUE(notMatches(MkStr("MyX x; f(x);"), ADLMatch));
+}
+
 TEST(Matcher, Call) {
   // FIXME: Do we want to overload Call() to directly take
   // Matcher<Decl>, too?
   StatementMatcher MethodX =
     callExpr(hasDeclaration(cxxMethodDecl(hasName("x"))));
 
   EXPECT_TRUE(matches("class Y { void x() { x(); } };", MethodX));
   EXPECT_TRUE(notMatches("class Y { void x() {} };", MethodX));