Complete the implementation of P2361 Unevaluated string literals

[cor3ntin]

Summary

The attributes changes were left out of Clang 17.
Attributes that used to take a string literal now accept an unevaluated
string literal instead, which means they reject numeric escape sequences
and strings literal with an encoding prefix - but the later was already
ill-formed in most cases.

We need to know that we are going to parse an unevaluated string literal
before we do - so we can reject numeric escape sequence,
so we derive from Attrs.td which attributes parameters are expected
to be string literals.

[aaron.ballman]

Can you update the patch description with more details about why these changes are being made in this way (to help people doing code archaeology in the future)?

clang/include/clang/Basic/DiagnosticCommonKinds.td

60

This duplicates part of err_attribute_argument_type; probably worth it to update that diagnostic so we get consistent diagnostic wording between attributes expecting string literal arguments.

clang/lib/Parse/ParseDeclCXX.cpp

1029

Spurious whitespace change is the only change in this file.

clang/lib/Parse/ParseExpr.cpp

3497–3499

Spurious brace changes are the only changes in this file.

clang/test/Parser/cxx-attributes.cpp

44

LOL this is a much better diagnostic than the previous one. :-D

[cor3ntin]

clang/include/clang/Basic/DiagnosticCommonKinds.td

60

I'm not sure there is a good way to do that without changing thousands of tests. I did look into it!

[aaron.ballman]

clang/include/clang/Basic/DiagnosticCommonKinds.td

60

If it's a slog, it can be done in a follow-up as an NFC commit.

[cor3ntin]

Update commit message and remove spurious changes

[Fznamznon]

clang/lib/Parse/ParseDecl.cpp

422

433–434

Should it be

Also, probably else can be removed since there is break above.

[cor3ntin]

Fix typo, remove dead code

[aaron.ballman]

LGTM with a minor formatting nit that @Fznamznon had pointed out but was missed.

clang/lib/Parse/ParseDecl.cpp

431–436

[cor3ntin]

clang/lib/Parse/ParseDecl.cpp

431–436

Oups, sorry @Fznamznon, I'll fix that!

[barannikov88]

clang/utils/TableGen/ClangAttrEmitter.cpp

2349

maskTrailingZeros might also be useful

[hubert.reinterpretcast]

clang/test/Parser/cxx0x-attributes.cpp

450–451

There should be corresponding C tests if, as the release notes text implies, the C behaviour changes (although, again, this direction has not been adopted by the C committee).

[cor3ntin]

Rebase, add C tests

[hubert.reinterpretcast]

clang/test/Parser/c2x-attributes.c

29

"Typo" fix.

clang/utils/TableGen/ClangAttrEmitter.cpp

2336

Typo fix

2349

@cor3ntin, this comment appears unaddressed.

Additionally, (just for future reference) ++N is suggested for the loop: https://llvm.org/docs/CodingStandards.html#prefer-preincrement.

[cor3ntin]

Address Hubert's feedback.

[hubert.reinterpretcast]

clang/lib/Parse/ParseDecl.cpp

431–436

It seems Aaron's request to move the code out of the else was not acted on.

clang/utils/TableGen/ClangAttrEmitter.cpp

2337

Minor nit: Grammar

2345

Do we know that Args.size() is less than 32?

2349–2350

#include <llvm/Support/MathExtras.h>

[cor3ntin]

Address Hubert's feedback

[cor3ntin]

clang/lib/Parse/ParseDecl.cpp

431–436

Not sure what happened there, I recall doing that. I guess not, thanks!

clang/utils/TableGen/ClangAttrEmitter.cpp

2345

I added an assert

[hubert.reinterpretcast]

Thanks, @cor3ntin, for addressing my feedback. I am not familiar enough with various aspects of it to approve it, but I see Aaron has already approved it and I think all comments have been addressed.
I also appreciate that the patch helps towards making the internally-used encoding less exposed.

clang/docs/ReleaseNotes.rst

 ^^^^^^^^^^^^^^^^^^^^^
 
 C++23 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
 C++2c Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
 
+- Attributes now expect unevaluated strings in attributes parameters that are string literals.
+  This is applied to both C++ standard attributes, and other attributes supported by Clang.
+  This completes the implementation of `P2361R6 Unevaluated Strings <https://wg21.link/P2361R6>_`
+
+
 Resolutions to C++ Defect Reports
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 C Language Changes
 ------------------
 
 C2x Feature Support
 ^^^^^^^^^^^^^^^^^^^

clang/include/clang/Basic/DiagnosticCommonKinds.td

 
 def err_expected_colon_after_setter_name : Error<
   "method name referenced in property setter attribute "
   "must end with ':'">;
 def err_expected_string_literal : Error<"expected string literal "
   "%select{in %1|for diagnostic message in static_assert|"
           "for optional message in 'availability' attribute|"
           "for %select{language name|source container name|USR}1 in "
-          "'external_source_symbol' attribute}0">;
+          "'external_source_symbol' attribute|"
+          "as argument of '%1' attribute}0">;
+
 def err_invalid_string_udl : Error<
   "string literal with user-defined suffix cannot be used here">;
 def err_invalid_character_udl : Error<
   "character literal with user-defined suffix cannot be used here">;
 def err_invalid_numeric_udl : Error<
   "numeric literal with user-defined suffix cannot be used here">;
 def warn_pragma_debug_missing_argument : Warning<
   "missing argument to debug command '%0'">, InGroup<IgnoredPragmas>;

clang/include/clang/Parse/Parser.h

private:
   /// Diagnose and skip C++11 and C2x attributes that appear in syntactic
   /// locations where attributes are not allowed.
   void DiagnoseAndSkipCXX11Attributes();
 
   /// Emit warnings for C++11 and C2x attributes that are in a position that
   /// clang accepts as an extension.
   void DiagnoseCXX11AttributeExtension(ParsedAttributes &Attrs);
 
+  ExprResult ParseUnevaluatedStringInAttribute(const IdentifierInfo &AttrName);
+
+  bool
+  ParseAttributeArgumentList(const clang::IdentifierInfo &AttrName,
+                             SmallVectorImpl<Expr *> &Exprs,
+                             ParsedAttributeArgumentsProperties ArgsProperties);
+
   /// Parses syntax-generic attribute arguments for attributes which are
   /// known to the implementation, and adds them to the given ParsedAttributes
   /// list with the given attribute syntax. Returns the number of arguments
   /// parsed for the attribute.
   unsigned
   ParseAttributeArgsCommon(IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
                            ParsedAttributes &Attrs, SourceLocation *EndLoc,
                            IdentifierInfo *ScopeName, SourceLocation ScopeLoc,

clang/include/clang/Sema/ParsedAttr.h

 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/ParsedAttrInfo.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Sema/Ownership.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/VersionTuple.h"
+#include <bitset>
 #include <cassert>
 #include <cstddef>
 #include <cstring>
 #include <utility>
 
 namespace clang {
 
 class ASTContext;
const ParsedAttr *getMSPropertyAttr() const {
     return nullptr;
   }
   bool hasMSPropertyAttr() const { return getMSPropertyAttr(); }
 
 private:
   VecTy AttrList;
 };
 
+struct ParsedAttributeArgumentsProperties {
+  ParsedAttributeArgumentsProperties(uint32_t StringLiteralBits)
+      : StringLiterals(StringLiteralBits) {}
+  bool isStringLiteralArg(unsigned I) const {
+    // If the last bit is set, assume we have a variadic parameter
+    if (I >= StringLiterals.size())
+      return StringLiterals.test(StringLiterals.size() - 1);
+    return StringLiterals.test(I);
+  }
+
+private:
+  std::bitset<32> StringLiterals;
+};
+
 /// 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:

clang/lib/Parse/ParseDecl.cpp

 static bool attributeHasIdentifierArg(const IdentifierInfo &II) {
 #define CLANG_ATTR_IDENTIFIER_ARG_LIST
   return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
 #include "clang/Parse/AttrParserStringSwitches.inc"
            .Default(false);
 #undef CLANG_ATTR_IDENTIFIER_ARG_LIST
 }
 
+/// Determine whether the given attribute has an identifier argument.
+static ParsedAttributeArgumentsProperties
+attributeStringLiteralListArg(const IdentifierInfo &II) {
+#define CLANG_ATTR_STRING_LITERAL_ARG_LIST
+  return llvm::StringSwitch<uint32_t>(normalizeAttrName(II.getName()))
+#include "clang/Parse/AttrParserStringSwitches.inc"
+      .Default(0);
+#undef CLANG_ATTR_STRING_LITERAL_ARG_LIST
+}
+
 /// Determine whether the given attribute has a variadic identifier argument.
 static bool attributeHasVariadicIdentifierArg(const IdentifierInfo &II) {
 #define CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
   return llvm::StringSwitch<bool>(normalizeAttrName(II.getName()))
 #include "clang/Parse/AttrParserStringSwitches.inc"
            .Default(false);
 #undef CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST
 }
if (T.isUsable())
     Attrs.addNewTypeAttr(&AttrName,
                          SourceRange(AttrNameLoc, Parens.getCloseLocation()),
                          ScopeName, ScopeLoc, T.get(), Form);
   else
     Attrs.addNew(&AttrName, SourceRange(AttrNameLoc, Parens.getCloseLocation()),
                  ScopeName, ScopeLoc, nullptr, 0, Form);
 }
 
+ExprResult
+Parser::ParseUnevaluatedStringInAttribute(const IdentifierInfo &AttrName) {
+  if (Tok.is(tok::l_paren)) {
+    BalancedDelimiterTracker Paren(*this, tok::l_paren);
+    Paren.consumeOpen();
+    ExprResult Res = ParseUnevaluatedStringInAttribute(AttrName);
+    Paren.consumeClose();
+    return Res;
+  }
+  if (!isTokenStringLiteral()) {
+    Diag(Tok.getLocation(), diag::err_expected_string_literal)
+        << /*in attribute...*/ 4 << AttrName.getName();
+    return ExprError();
+  }
+  return ParseUnevaluatedStringLiteralExpression();
+}
+
+bool Parser::ParseAttributeArgumentList(
+    const IdentifierInfo &AttrName, SmallVectorImpl<Expr *> &Exprs,
+    ParsedAttributeArgumentsProperties ArgsProperties) {
+  bool SawError = false;
+  unsigned Arg = 0;
+  while (true) {
+    ExprResult Expr;
+    if (ArgsProperties.isStringLiteralArg(Arg)) {
+      Expr = ParseUnevaluatedStringInAttribute(AttrName);
+    } else if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
+      Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
+      Expr = ParseBraceInitializer();
+    } else {
+      Expr = ParseAssignmentExpression();
+    }
+    Expr = Actions.CorrectDelayedTyposInExpr(Expr);
+
+    if (Tok.is(tok::ellipsis))
+      Expr = Actions.ActOnPackExpansion(Expr.get(), ConsumeToken());
+    else if (Tok.is(tok::code_completion)) {
+      // There's nothing to suggest in here as we parsed a full expression.
+      // Instead fail and propogate the error since caller might have something
+      // the suggest, e.g. signature help in function call. Note that this is
+      // performed before pushing the \p Expr, so that signature help can report
+      // current argument correctly.
+      SawError = true;
+      cutOffParsing();
+      break;
+    }
+
+    if (Expr.isInvalid()) {
+      SawError = true;
+      break;
+      SkipUntil(tok::comma, tok::r_paren, StopBeforeMatch);
+    } else {
+      Exprs.push_back(Expr.get());
+    }
+
+    if (Tok.isNot(tok::comma))
+      break;
+    // Move to the next argument, remember where the comma was.
+    Token Comma = Tok;
+    ConsumeToken();
+    checkPotentialAngleBracketDelimiter(Comma);
+    Arg++;
+  }
+
+  if (SawError) {
+    // Ensure typos get diagnosed when errors were encountered while parsing the
+    // expression list.
+    for (auto &E : Exprs) {
+      ExprResult Expr = Actions.CorrectDelayedTyposInExpr(E);
+      if (Expr.isUsable())
+        E = Expr.get();
+    }
+  }
+  return SawError;
+}
+
 unsigned Parser::ParseAttributeArgsCommon(
     IdentifierInfo *AttrName, SourceLocation AttrNameLoc,
     ParsedAttributes &Attrs, SourceLocation *EndLoc, IdentifierInfo *ScopeName,
     SourceLocation ScopeLoc, ParsedAttr::Form Form) {
   // Ignore the left paren location for now.
   ConsumeParen();
 
   bool ChangeKWThisToIdent = attributeTreatsKeywordThisAsIdentifier(*AttrName);
if (AttributeIsTypeArgAttr) {
       // General case. Parse all available expressions.
       bool Uneval = attributeParsedArgsUnevaluated(*AttrName);
       EnterExpressionEvaluationContext Unevaluated(
           Actions, Uneval
                        ? Sema::ExpressionEvaluationContext::Unevaluated
                        : Sema::ExpressionEvaluationContext::ConstantEvaluated);
 
       ExprVector ParsedExprs;
-      if (ParseExpressionList(ParsedExprs, llvm::function_ref<void()>(),
-                              /*FailImmediatelyOnInvalidExpr=*/true,
-                              /*EarlyTypoCorrection=*/true)) {
+      ParsedAttributeArgumentsProperties ArgProperties =
+          attributeStringLiteralListArg(*AttrName);
+      if (ParseAttributeArgumentList(*AttrName, ParsedExprs, ArgProperties)) {
         SkipUntil(tok::r_paren, StopAtSemi);
         return 0;
       }
 
       // Pack expansion must currently be explicitly supported by an attribute.
       for (size_t I = 0; I < ParsedExprs.size(); ++I) {
         if (!isa<PackExpansionExpr>(ParsedExprs[I]))
           continue;

clang/lib/Parse/ParseDeclCXX.cpp

if (Tok.is(tok::r_paren)) {
     else if (getLangOpts().CPlusPlus26)
       AssertMessage = ParseConstantExpressionInExprEvalContext();
     else {
       Diag(Tok, diag::err_expected_string_literal)
           << /*Source='static_assert'*/ 1;
       SkipMalformedDecl();
       return nullptr;
     }
-
     if (AssertMessage.isInvalid()) {
       SkipMalformedDecl();
       return nullptr;
     }
   }
 
   T.consumeClose();
 

clang/lib/Parse/ParseExpr.cpp

bool Parser::ParseExpressionList(SmallVectorImpl<Expr *> &Exprs,
   while (true) {
     if (ExpressionStarts)
       ExpressionStarts();
 
     ExprResult Expr;
     if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
       Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
       Expr = ParseBraceInitializer();
-    } else
+    } else {
       Expr = ParseAssignmentExpression();
-
+    }
     if (EarlyTypoCorrection)
       Expr = Actions.CorrectDelayedTyposInExpr(Expr);
 
     if (Tok.is(tok::ellipsis))
       Expr = Actions.ActOnPackExpansion(Expr.get(), ConsumeToken());
     else if (Tok.is(tok::code_completion)) {
       // There's nothing to suggest in here as we parsed a full expression.
       // Instead fail and propogate the error since caller might have something

clang/lib/Sema/SemaDeclAttr.cpp

 /// and return true.
 bool Sema::checkStringLiteralArgumentAttr(const AttributeCommonInfo &CI,
                                           const Expr *E, StringRef &Str,
                                           SourceLocation *ArgLocation) {
   const auto *Literal = dyn_cast<StringLiteral>(E->IgnoreParenCasts());
   if (ArgLocation)
     *ArgLocation = E->getBeginLoc();
 
-  if (!Literal || !Literal->isOrdinary()) {
+  if (!Literal || (!Literal->isUnevaluated() && !Literal->isOrdinary())) {
     Diag(E->getBeginLoc(), diag::err_attribute_argument_type)
         << CI << AANT_ArgumentString;
     return false;
   }
 
   Str = Literal->getString();
   return true;
 }
if (AL.isArgIdent(ArgNum)) {
     Str = Loc->Ident->getName();
     if (ArgLocation)
       *ArgLocation = Loc->Loc;
     return true;
   }
 
   // Now check for an actual string literal.
   Expr *ArgExpr = AL.getArgAsExpr(ArgNum);
+  const auto *Literal = dyn_cast<StringLiteral>(ArgExpr->IgnoreParenCasts());
+  if (ArgLocation)
+    *ArgLocation = ArgExpr->getBeginLoc();
+
+  if (!Literal || (!Literal->isUnevaluated() && !Literal->isOrdinary())) {
+    Diag(ArgExpr->getBeginLoc(), diag::err_attribute_argument_type)
+        << AL << AANT_ArgumentString;
+    return false;
+  }
+  Str = Literal->getString();
   return checkStringLiteralArgumentAttr(AL, ArgExpr, Str, ArgLocation);
 }
 
 /// Applies the given attribute to the Decl without performing any
 /// additional semantic checking.
 template <typename AttrType>
 static void handleSimpleAttribute(Sema &S, Decl *D,
                                   const AttributeCommonInfo &CI) {

clang/test/Parser/MicrosoftExtensions.cpp

 typedef struct _GUID
 {
     unsigned long  Data1;
     unsigned short Data2;
     unsigned short Data3;
     unsigned char  Data4[8];
 } GUID;
 
-struct __declspec(uuid(L"00000000-0000-0000-1234-000000000047")) uuid_attr_bad1 { };// expected-error {{'uuid' attribute requires a string}}
-struct __declspec(uuid(3)) uuid_attr_bad2 { };// expected-error {{'uuid' attribute requires a string}}
+struct __declspec(uuid(L"00000000-0000-0000-1234-000000000047")) uuid_attr_bad1 { };// expected-error {{an unevaluated string literal cannot have an encoding prefix}}
+struct __declspec(uuid(3)) uuid_attr_bad2 { };// expected-error {{expected string literal as argument of 'uuid' attribute}}
 struct __declspec(uuid("0000000-0000-0000-1234-0000500000047")) uuid_attr_bad3 { };// expected-error {{uuid attribute contains a malformed GUID}}
 struct __declspec(uuid("0000000-0000-0000-Z234-000000000047")) uuid_attr_bad4 { };// expected-error {{uuid attribute contains a malformed GUID}}
 struct __declspec(uuid("000000000000-0000-1234-000000000047")) uuid_attr_bad5 { };// expected-error {{uuid attribute contains a malformed GUID}}
 [uuid("000000000000-0000-1234-000000000047")] struct uuid_attr_bad6 { };// expected-error {{uuid attribute contains a malformed GUID}}
 
 __declspec(uuid("000000A0-0000-0000-C000-000000000046")) int i; // expected-warning {{'uuid' attribute only applies to structs, unions, classes, and enums}}
 
 struct __declspec(uuid("000000A0-0000-0000-C000-000000000046"))

clang/test/Parser/c2x-attributes.c

 [[]] enum E2 { Five }; // expected-error {{misplaced attributes}}
 
 // FIXME: this diagnostic can be improved.
 enum { [[]] Six }; // expected-error {{expected identifier}}
 
 // FIXME: this diagnostic can be improved.
 enum E3 [[]] { Seven }; // expected-error {{expected identifier or '('}}
 
-[[deprecated([""])]] int WrongArgs; // expected-error {{expected expression}}
+[[deprecated([""])]] int WrongArgs; // expected-error {{expected string literal as argument of 'deprecated' attribute}}
 [[,,,,,]] int Commas1; // ok
 [[,, maybe_unused]] int Commas2; // ok
 [[maybe_unused,,,]] int Commas3; // ok
 [[,,maybe_unused,]] int Commas4; // ok
 [[foo bar]] int NoComma; // expected-error {{expected ','}} \
                          // expected-warning {{unknown attribute 'foo' ignored}}
 
 struct [[]] S1 {
   int i [[]];
   int [[]] j;
   int k[10] [[]];
   int l[[]][10];
   [[]] int m, n;
   int o [[]] : 12;
   int [[]] : 0; // OK, attribute applies to the type.
   int p, [[]] : 0; // expected-error {{an attribute list cannot appear here}}
   int q, [[]] r; // expected-error {{an attribute list cannot appear here}}
   [[]] int; // expected-error {{an attribute list cannot appear here}} \

clang/test/Parser/cxx-attributes.cpp

void fn() {
   void (&__attribute__((attr)) fn_lref)() = fn; // expected-warning{{unknown attribute 'attr' ignored}}
   void (&&__attribute__((attr)) fn_rref)() = fn; // expected-warning{{unknown attribute 'attr' ignored}}
 
   int i[5];
   int (*__attribute__((attr(i[1]))) pi);  // expected-warning{{unknown attribute 'attr' ignored}}
   pi = &i[0];
 }
 
-[[deprecated([""])]] int WrongArgs; // expected-error {{expected variable name or 'this' in lambda capture list}}
+[[deprecated([""])]] int WrongArgs; // expected-error {{expected string literal as argument of 'deprecated' attribute}}
 [[,,,,,]] int Commas1; // ok
 [[,, maybe_unused]] int Commas2; // ok
 [[maybe_unused,,,]] int Commas3; // ok
 [[,,maybe_unused,]] int Commas4; // ok
 [[foo bar]] int NoComma; // expected-error {{expected ','}} \
                          // expected-warning {{unknown attribute 'foo' ignored}}
 // expected-error@+2 2 {{expected ']'}}
 // expected-error@+1 {{expected external declaration}}
 [[foo

clang/test/Parser/cxx0x-attributes.cpp

class [[]] [[]] final_class
   alignas(float) [[]] final // expected-error {{an attribute list cannot appear here}}
   alignas(float) [[]] [[]] alignas(float): base{}; // expected-error {{an attribute list cannot appear here}}
 
 class [[]] [[]] final_class_another
   [[]] [[]] alignas(16) final // expected-error {{an attribute list cannot appear here}}
   [[]] [[]] alignas(16) [[]]{}; // expected-error {{an attribute list cannot appear here}}
 
 // The diagnostics here don't matter much, this just shouldn't crash:
-class C final [[deprecated(l]] {}); // expected-error {{use of undeclared identifier}} expected-error {{expected ']'}} expected-error {{an attribute list cannot appear here}} expected-error {{expected unqualified-id}}
+class C final [[deprecated(l]] {}); //expected-error {{expected string literal as argument of 'deprecated' attribute}} expected-error {{an attribute list cannot appear here}} expected-error {{expected unqualified-id}}
 class D final alignas ([l) {}]{}); // expected-error {{expected ',' or ']' in lambda capture list}} expected-error {{an attribute list cannot appear here}}
 
 [[]] struct with_init_declarators {} init_declarator;
 [[]] struct no_init_declarators; // expected-error {{misplaced attributes}}
 template<typename> [[]] struct no_init_declarators_template; // expected-error {{an attribute list cannot appear here}}
 void fn_with_structs() {
   [[]] struct with_init_declarators {} init_declarator;
   [[]] struct no_init_declarators; // expected-error {{an attribute list cannot appear here}}

 }
 
 template<typename...Ts> void variadic() {
   void bar [[noreturn...]] (); // expected-error {{attribute 'noreturn' cannot be used as an attribute pack}}
 }
 
 template <int... Is> void variadic_nttp() {
   void bar [[noreturn...]] ();                        // expected-error {{attribute 'noreturn' cannot be used as an attribute pack}}
-  void baz [[clang::no_sanitize(Is...)]] ();          // expected-error {{attribute 'no_sanitize' does not support argument pack expansion}}
+  void baz [[clang::no_sanitize(Is...)]] ();          // expected-error {{expected string literal as argument of 'no_sanitize' attribute}}
   void bor [[clang::annotate("A", "V" ...)]] ();      // expected-error {{pack expansion does not contain any unexpanded parameter packs}}
   void bir [[clang::annotate("B", {1, 2, 3, 4})]] (); // expected-error {{'annotate' attribute requires parameter 1 to be a constant expression}} expected-note {{subexpression not valid in a constant expression}}
   void boo [[unknown::foo(Is...)]] ();                // expected-warning {{unknown attribute 'foo' ignored}}
   void faz [[clang::annotate("C", (Is + ...))]] ();   // expected-warning {{pack fold expression is a C++17 extension}}
   void far [[clang::annotate("D", Is...)]] ();
   void foz [[clang::annotate("E", 1, 2, 3, Is...)]] ();
   void fiz [[clang::annotate("F", Is..., 1, 2, 3)]] ();
   void fir [[clang::annotate("G", 1, Is..., 2, 3)]] ();
class Ordering {
   ) {
   }
 
   void f4(
       int (*)(__attribute__(()) [[]] int n) // expected-error {{an attribute list cannot appear here}}
   ) {
   }
 };
+
+namespace P2361 {
+[[deprecated(L"abc")]] void a(); // expected-error{{an unevaluated string literal cannot have an encoding prefix}}
+[[nodiscard("\123")]] int b(); // expected-error{{invalid escape sequence '\123' in an unevaluated string literal}}
+}

clang/test/Sema/MicrosoftExtensions.c

 const int anon_falt_size = sizeof(struct anon_fault);
 
 __declspec(deprecated("This is deprecated")) enum DE1 { one, two } e1; // expected-note {{'e1' has been explicitly marked deprecated here}}
 struct __declspec(deprecated) DS1 { int i; float f; }; // expected-note {{'DS1' has been explicitly marked deprecated here}}
 
 #define MY_TEXT   "This is also deprecated"
 __declspec(deprecated(MY_TEXT)) void Dfunc1( void ) {} // expected-note {{'Dfunc1' has been explicitly marked deprecated here}}
 
-struct __declspec(deprecated(123)) DS2 {};  // expected-error {{'deprecated' attribute requires a string}}
+struct __declspec(deprecated(123)) DS2 {};  // expected-error {{expected string literal as argument of 'deprecated' attribute}}
 
 void test( void ) {
   e1 = one; // expected-warning {{'e1' is deprecated: This is deprecated}}
   struct DS1 s = { 0 };  // expected-warning {{'DS1' is deprecated}}
   Dfunc1(); // expected-warning {{'Dfunc1' is deprecated: This is also deprecated}}
 
   enum DE1 no;  // no warning because E1 is not deprecated
 }

clang/test/Sema/annotate-type.c

void foo(float *[[clang::annotate_type("foo")]] a) {
   // GNU spelling is not supported
   int __attribute__((annotate_type("bar"))) y1;  // expected-warning {{unknown attribute 'annotate_type' ignored}}
   int *__attribute__((annotate_type("bar"))) y2; // expected-warning {{unknown attribute 'annotate_type' ignored}}
 
   // Various error cases
   [[clang::annotate_type("bar")]] int *z1; // expected-error {{'annotate_type' attribute cannot be applied to a declaration}}
   int *z2 [[clang::annotate_type("bar")]]; // expected-error {{'annotate_type' attribute cannot be applied to a declaration}}
   [[clang::annotate_type("bar")]]; // expected-error {{'annotate_type' attribute cannot be applied to a statement}}
-  int *[[clang::annotate_type(1)]] z3; // expected-error {{'annotate_type' attribute requires a string}}
+  int *[[clang::annotate_type(1)]] z3; // expected-error {{expected string literal as argument of 'annotate_type' attribute}}
   int *[[clang::annotate_type()]] z4; // expected-error {{'annotate_type' attribute takes at least 1 argument}}
   int *[[clang::annotate_type]] z5; // expected-error {{'annotate_type' attribute takes at least 1 argument}}
-  int *[[clang::annotate_type(some_function())]] z6; // expected-error {{'annotate_type' attribute requires a string}}
+  int *[[clang::annotate_type(some_function())]] z6; // expected-error {{expected string literal as argument of 'annotate_type' attribute}}
   int *[[clang::annotate_type("bar", some_function())]] z7; // expected-error {{'annotate_type' attribute requires parameter 1 to be a constant expression}} expected-note{{subexpression not valid in a constant expression}}
   int *[[clang::annotate_type("bar", z7)]] z8; // expected-error {{'annotate_type' attribute requires parameter 1 to be a constant expression}} expected-note{{subexpression not valid in a constant expression}}
   int *[[clang::annotate_type("bar", int)]] z9; // expected-error {{expected expression}}
 }
 // More error cases: Prohibit adding the attribute to declarations.
 // Different declarations hit different code paths, so they need separate tests.
 [[clang::annotate_type("bar")]] int *global; // expected-error {{'annotate_type' attribute cannot be applied to a declaration}}
 [[clang::annotate_type("bar")]] void annotated_function(); // expected-error {{'annotate_type' attribute cannot be applied to a declaration}}

clang/test/Sema/annotate.c

 // RUN: %clang_cc1 %s -fsyntax-only -verify
 
 void __attribute__((annotate("foo"))) foo(float *a) {
   __attribute__((annotate("bar"))) int x;
   [[clang::annotate("bar")]] int x2;
-  __attribute__((annotate(1))) int y; // expected-error {{'annotate' attribute requires a string}}
-  [[clang::annotate(1)]] int y2; // expected-error {{'annotate' attribute requires a string}}
+  __attribute__((annotate(1))) int y; // expected-error {{expected string literal as argument of 'annotate' attribute}}
+  [[clang::annotate(1)]] int y2; // expected-error {{expected string literal as argument of 'annotate' attribute}}
   __attribute__((annotate("bar", 1))) int z;
   [[clang::annotate("bar", 1)]] int z2;
 
   int u = __builtin_annotation(z, (char*) 0); // expected-error {{second argument to __builtin_annotation must be a non-wide string constant}}
   int v = __builtin_annotation(z, (char*) L"bar"); // expected-error {{second argument to __builtin_annotation must be a non-wide string constant}}
   int w = __builtin_annotation(z, "foo");
   float b = __builtin_annotation(*a, "foo"); // expected-error {{first argument to __builtin_annotation must be an integer}}
 
   __attribute__((annotate())) int c; // expected-error {{'annotate' attribute takes at least 1 argument}}
   [[clang::annotate()]] int c2;      // expected-error {{'annotate' attribute takes at least 1 argument}}
 }

clang/test/Sema/attr-assume.c

 // RUN: %clang_cc1 -triple i386-apple-darwin9 -fsyntax-only -verify %s
 
-void f1(void) __attribute__((assume(3))); // expected-error {{'assume' attribute requires a string}}
-void f2(void) __attribute__((assume(int))); // expected-error {{expected expression}}
-void f3(void) __attribute__((assume(for))); // expected-error {{expected expression}}
+void f1(void) __attribute__((assume(3))); // expected-error {{expected string literal as argument of 'assume' attribute}}
+void f2(void) __attribute__((assume(int))); // expected-error {{expected string literal as argument of 'assume' attribute}}
+void f3(void) __attribute__((assume(for))); // expected-error {{expected string literal as argument of 'assume' attribute}}
 void f4(void) __attribute__((assume("QQQQ"))); // expected-warning {{unknown assumption string 'QQQQ'; attribute is potentially ignored}}
 void f5(void) __attribute__((assume("omp_no_openmp")));
 void f6(void) __attribute__((assume("omp_noopenmp"))); // expected-warning {{unknown assumption string 'omp_noopenmp' may be misspelled; attribute is potentially ignored, did you mean 'omp_no_openmp'?}}
 void f7(void) __attribute__((assume("omp_no_openmp_routine"))); // expected-warning {{unknown assumption string 'omp_no_openmp_routine' may be misspelled; attribute is potentially ignored, did you mean 'omp_no_openmp_routines'?}}
 void f8(void) __attribute__((assume("omp_no_openmp1"))); // expected-warning {{unknown assumption string 'omp_no_openmp1' may be misspelled; attribute is potentially ignored, did you mean 'omp_no_openmp'?}}
 void f9(void) __attribute__((assume("omp_no_openmp", "omp_no_openmp"))); // expected-error {{'assume' attribute takes one argument}}
 
-int g1 __attribute__((assume(0))); // expected-warning {{'assume' attribute only applies to functions and Objective-C methods}}
+int g1 __attribute__((assume(0))); // expected-error {{expected string literal as argument of 'assume' attribute}}
 int g2 __attribute__((assume("omp_no_openmp"))); // expected-warning {{'assume' attribute only applies to functions and Objective-C methods}}

clang/test/Sema/attr-btf_tag.c

 struct __tag1 t2;
 struct __tag2 __tag3 t2 {
   int a __tag1;
 };
 
 int g1 __tag1;
 int g2 __tag_no_arg; // expected-error {{'btf_decl_tag' attribute takes one argument}}
 int g3 __tag_2_arg; // expected-error {{'btf_decl_tag' attribute takes one argument}}
-int i1 __invalid; // expected-error {{'btf_decl_tag' attribute requires a string}}
+int i1 __invalid; // expected-error {{expected string literal as argument of 'btf_decl_tag' attribute}}
 
 enum e1 {
   E1
 } __tag1; // expected-error {{'btf_decl_tag' attribute only applies to variables, functions, structs, unions, classes, non-static data members, and typedefs}}
 
 enum e2 {
   E2
 } __tag_no_arg; // expected-error {{'btf_decl_tag' attribute only applies to variables, functions, structs, unions, classes, non-static data members, and typedefs}}

clang/test/Sema/attr-btf_type_tag.c

 // RUN: %clang_cc1 -x c -triple x86_64-pc-linux-gnu -dwarf-version=4 -fsyntax-only -verify %s
 
 #define __tag1 __attribute__((btf_type_tag("tag1")))
 #define __tag2 __attribute__((btf_type_tag("tag2")))
 #define __tag3 __attribute__((btf_type_tag("tag3")))
 #define __tag4 __attribute__((btf_type_tag("tag4")))
 #define __tag5 __attribute__((btf_type_tag("tag5")))
 #define __tag6 __attribute__((btf_type_tag("tag6")))
 
 int __attribute__((btf_type_tag("tag1", "tag2"))) *invalid1; // expected-error {{'btf_type_tag' attribute takes one argument}}
-int __attribute__((btf_type_tag(2))) *invalid2; // expected-error {{'btf_type_tag' attribute requires a string}}
+int __attribute__((btf_type_tag(2))) *invalid2; // expected-error {{expected string literal as argument of 'btf_type_tag' attribute}}
 
 int * __tag1 __tag2 * __tag3 __tag4 * __tag5 __tag6 *g;
 
 typedef void __fn_t(int);
 typedef __fn_t __tag1 __tag2 * __tag3 __tag4 *__fn2_t;
 struct t {
   int __tag1 * __tag2 * __tag3 *a;
   int __tag1 __tag2 __tag3 *b;

clang/test/Sema/attr-capabilities.c

 struct __attribute__((capability("custom"))) CustomName {};
 
 int Test1 __attribute__((capability("test1")));  // expected-error {{'capability' attribute only applies to structs, unions, classes, and typedefs}}
 int Test2 __attribute__((shared_capability("test2"))); // expected-error {{'shared_capability' attribute only applies to structs, unions, classes, and typedefs}}
 int Test3 __attribute__((acquire_capability("test3")));  // expected-warning {{'acquire_capability' attribute only applies to functions}}
 int Test4 __attribute__((try_acquire_capability("test4"))); // expected-error {{'try_acquire_capability' attribute only applies to functions}}
 int Test5 __attribute__((release_capability("test5"))); // expected-warning {{'release_capability' attribute only applies to functions}}
 
-struct __attribute__((capability(12))) Test3 {}; // expected-error {{'capability' attribute requires a string}}
-struct __attribute__((shared_capability(Test2))) Test4 {}; // expected-error {{'shared_capability' attribute requires a string}}
+struct __attribute__((capability(12))) Test3 {}; // expected-error {{expected string literal as argument of 'capability' attribute}}
+struct __attribute__((shared_capability(Test2))) Test4 {}; // expected-error {{expected string literal as argument of 'shared_capability' attribute}}
 
 struct __attribute__((capability)) Test5 {}; // expected-error {{'capability' attribute takes one argument}}
 struct __attribute__((shared_capability("test1", 12))) Test6 {}; // expected-error {{'shared_capability' attribute takes one argument}}
 
 struct NotACapability BadCapability;
 ThreadRole GUI, Worker;
 void Func1(void) __attribute__((requires_capability(GUI))) {}
 void Func2(void) __attribute__((requires_shared_capability(Worker))) {}

clang/test/Sema/attr-enforce-tcb-errors.cpp

 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
 [[clang::enforce_tcb("oops")]] int wrong_subject_type; // expected-warning{{'enforce_tcb' attribute only applies to functions}}
 
 void no_arguments() __attribute__((enforce_tcb)); // expected-error{{'enforce_tcb' attribute takes one argument}}
 
 void too_many_arguments() __attribute__((enforce_tcb("test", 12))); // expected-error{{'enforce_tcb' attribute takes one argument}}
 
-void wrong_argument_type() __attribute__((enforce_tcb(12))); // expected-error{{'enforce_tcb' attribute requires a string}}
+void wrong_argument_type() __attribute__((enforce_tcb(12))); // expected-error{{expected string literal as argument of 'enforce_tcb' attribute}}
 
 [[clang::enforce_tcb_leaf("oops")]] int wrong_subject_type_leaf; // expected-warning{{'enforce_tcb_leaf' attribute only applies to functions}}
 
 void no_arguments_leaf() __attribute__((enforce_tcb_leaf)); // expected-error{{'enforce_tcb_leaf' attribute takes one argument}}
 
 void too_many_arguments_leaf() __attribute__((enforce_tcb_leaf("test", 12))); // expected-error{{'enforce_tcb_leaf' attribute takes one argument}}
-void wrong_argument_type_leaf() __attribute__((enforce_tcb_leaf(12))); // expected-error{{'enforce_tcb_leaf' attribute requires a string}}
+void wrong_argument_type_leaf() __attribute__((enforce_tcb_leaf(12))); // expected-error{{expected string literal as argument of 'enforce_tcb_leaf' attribute}}
 
 void foo();
 
 __attribute__((enforce_tcb("x")))
 __attribute__((enforce_tcb_leaf("x"))) // expected-error{{attributes 'enforce_tcb_leaf("x")' and 'enforce_tcb("x")' are mutually exclusive}}
 void both_tcb_and_tcb_leaf() {
   foo(); // no-warning
 }

clang/test/Sema/attr-enforce-tcb-errors.m

 - (void)onInterfaceOnly __attribute__((enforce_tcb("test")));
 @end
 
 @interface AClass (NoImplementation)
 - (void)noArguments __attribute__((enforce_tcb)); // expected-error{{'enforce_tcb' attribute takes one argument}}
 
 - (void)tooManyArguments __attribute__((enforce_tcb("test", 12))); // expected-error{{'enforce_tcb' attribute takes one argument}}
 
-- (void)wrongArgumentType __attribute__((enforce_tcb(12))); // expected-error{{'enforce_tcb' attribute requires a string}}
+- (void)wrongArgumentType __attribute__((enforce_tcb(12))); // expected-error{{expected string literal as argument of 'enforce_tcb' attribute}}
 
 - (void)noArgumentsLeaf __attribute__((enforce_tcb_leaf)); // expected-error{{'enforce_tcb_leaf' attribute takes one argument}}
 
 - (void)tooManyArgumentsLeaf __attribute__((enforce_tcb_leaf("test", 12))); // expected-error{{'enforce_tcb_leaf' attribute takes one argument}}
 
-- (void)wrongArgumentTypeLeaf __attribute__((enforce_tcb_leaf(12))); // expected-error{{'enforce_tcb_leaf' attribute requires a string}}
+- (void)wrongArgumentTypeLeaf __attribute__((enforce_tcb_leaf(12))); // expected-error{{expected string literal as argument of 'enforce_tcb_leaf' attribute}}
 @end
 
 @implementation AClass
 - (void)onInterfaceOnly {
   foo(); // expected-warning{{calling 'foo' is a violation of trusted computing base 'test'}}
 }
 
 - (void)bothTCBAndTCBLeaf

clang/test/Sema/attr-error.c

 bad0(void);
 
 int bad1(__attribute__((error("bad1"))) int param); // expected-error {{'error' attribute only applies to functions}}
 
 int bad2(void) {
   __attribute__((error("bad2"))); // expected-error {{'error' attribute cannot be applied to a statement}}
 }
 
-__attribute__((error(3))) // expected-error {{'error' attribute requires a string}}
+__attribute__((error(3))) // expected-error {{expected string literal as argument of 'error' attribute}}
 int
 bad3(void);
 
 __attribute__((error("foo"), error("foo"))) int good1(void);
 __attribute__((error("foo"))) int good1(void);
 __attribute__((error("foo"))) int good1(void) {}
 
 __attribute__((error("foo"), warning("foo"))) // expected-error {{'warning' and 'error' attributes are not compatible}}

clang/test/Sema/attr-handles.cpp

 // RUN: %clang_cc1  -fsyntax-only -verify %s
 
 // Decl annotations.
 void f(int *a __attribute__((acquire_handle("Fuchsia"))));
 void (*fp)(int handle [[clang::use_handle("Fuchsia")]]);
 auto lambda = [](int handle [[clang::use_handle("Fuchsia")]]){};
 void g(int a __attribute__((acquire_handle("Fuchsia")))); // expected-error {{attribute only applies to output parameters}}
 void h(int *a __attribute__((acquire_handle))); // expected-error {{'acquire_handle' attribute takes one argument}}
-void h(int *a __attribute__((acquire_handle(1)))); // expected-error {{attribute requires a string}}
+void h(int *a __attribute__((acquire_handle(1)))); // expected-error {{expected string literal as argument of 'acquire_handle' attribute}}
 void h(int *a __attribute__((acquire_handle("RandomString", "AndAnother")))); // expected-error {{'acquire_handle' attribute takes one argument}}
 __attribute__((release_handle("Fuchsia"))) int i(); // expected-warning {{'release_handle' attribute only applies to parameters}}
 __attribute__((use_handle("Fuchsia"))) int j(); // expected-warning {{'use_handle' attribute only applies to parameters}}
 int a __attribute__((acquire_handle("Fuchsia"))); // expected-warning {{'acquire_handle' attribute only applies to functions, typedefs, and parameters}}
 int (* __attribute__((acquire_handle("Fuchsia"))) fpt)(char *); // expected-warning {{'acquire_handle' attribute only applies to functions, typedefs, and parameters}}
 
 // Type annotations.
 auto lambdat = [](int handle __attribute__((use_handle("Fuchsia"))))
     __attribute__((acquire_handle("Fuchsia"))) -> int { return 0; };
 int __attribute((acquire_handle("Fuchsia"))) ta; // expected-warning {{'acquire_handle' attribute only applies to functions, typedefs, and parameters}}
 int open(const char *path, int flags, ...) [[clang::acquire_handle]]; // expected-error {{'acquire_handle' attribute takes one argument}}
 
 // Typedefs.
 typedef int callback(char *) __attribute__((acquire_handle("Fuchsia")));

clang/test/Sema/attr-section.c

 // RUN: %clang_cc1 -verify -fsyntax-only -triple x86_64-apple-darwin9 %s
 
 int x __attribute__((section(
-   42)));  // expected-error {{'section' attribute requires a string}}
+   42)));  // expected-error {{expected string literal as argument of 'section' attribute}}
 
 
 // rdar://4341926
 int y __attribute__((section(
    "sadf"))); // expected-error {{mach-o section specifier requires a segment and section separated by a comma}}
 
 // PR6007
 void test(void) {

clang/test/Sema/attr-tls_model.c

 // RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -verify -fsyntax-only %s
 
 #if !__has_attribute(tls_model)
 #error "Should support tls_model attribute"
 #endif
 
 int f(void) __attribute((tls_model("global-dynamic"))); // expected-error {{'tls_model' attribute only applies to thread-local variables}}
 
 int x __attribute((tls_model("global-dynamic"))); // expected-error {{'tls_model' attribute only applies to thread-local variables}}
 static __thread int y __attribute((tls_model("global-dynamic"))); // no-warning
 
 static __thread int y __attribute((tls_model("local", "dynamic"))); // expected-error {{'tls_model' attribute takes one argument}}
-static __thread int y __attribute((tls_model(123))); // expected-error {{'tls_model' attribute requires a string}}
+static __thread int y __attribute((tls_model(123))); // expected-error {{expected string literal as argument of 'tls_model' attribute}}
 static __thread int y __attribute((tls_model("foobar"))); // expected-error {{tls_model must be "global-dynamic", "local-dynamic", "initial-exec" or "local-exec"}}

clang/test/Sema/attr-unavailable-message.c

 // RUN: %clang_cc1 -fsyntax-only -verify %s
 // rdar: //6734520
 
 void tooManyArgs(void) __attribute__((unavailable("a", "b"))); // expected-error {{'unavailable' attribute takes no more than 1 argument}}
 
 int foo(int)  __attribute__((__unavailable__("USE IFOO INSTEAD"))); // expected-note {{'foo' has been explicitly marked unavailable here}}
 double dfoo(double)  __attribute__((__unavailable__("NO LONGER"))); // expected-note 2 {{'dfoo' has been explicitly marked unavailable here}}
 
 void bar(void) __attribute__((__unavailable__)); // expected-note {{explicitly marked unavailable}}
 
-int quux(void) __attribute__((__unavailable__(12))); // expected-error {{'__unavailable__' attribute requires a string}}
+int quux(void) __attribute__((__unavailable__(12))); // expected-error {{expected string literal as argument of '__unavailable__' attribute}}
 
 #define ACCEPTABLE  "Use something else"
 int quux2(void) __attribute__((__unavailable__(ACCEPTABLE)));
 
 void test_foo(void) {
   int ir = foo(1); // expected-error {{'foo' is unavailable: USE IFOO INSTEAD}}
   double dr = dfoo(1.0); // expected-error {{'dfoo' is unavailable: NO LONGER}}
 

clang/test/Sema/attr-warning.c

 bad0(void);
 
 int bad1(__attribute__((warning("bad1"))) int param); // expected-error {{'warning' attribute only applies to functions}}
 
 int bad2(void) {
   __attribute__((warning("bad2"))); // expected-error {{'warning' attribute cannot be applied to a statement}}
 }
 
-__attribute__((warning(3))) // expected-error {{'warning' attribute requires a string}}
+__attribute__((warning(3))) // expected-error {{expected string literal as argument of 'warning' attribute}}
 int
 bad3(void);
 
 __attribute__((warning("foo"), warning("foo"))) int good1(void);
 __attribute__((warning("foo"))) int good1(void);
 __attribute__((warning("foo"))) int good1(void) {}
 
 __attribute__((warning("foo"), error("foo"))) // expected-error {{'error' and 'warning' attributes are not compatible}}

clang/test/Sema/diagnose_if.c

 // RUN: %clang_cc1 %s -verify -fno-builtin
 
 #define _diagnose_if(...) __attribute__((diagnose_if(__VA_ARGS__)))
 
 void failure1(void) _diagnose_if(); // expected-error{{exactly 3 arguments}}
 void failure2(void) _diagnose_if(0); // expected-error{{exactly 3 arguments}}
 void failure3(void) _diagnose_if(0, ""); // expected-error{{exactly 3 arguments}}
 void failure4(void) _diagnose_if(0, "", "error", 1); // expected-error{{exactly 3 arguments}}
-void failure5(void) _diagnose_if(0, 0, "error"); // expected-error{{requires a string}}
+void failure5(void) _diagnose_if(0, 0, "error"); // expected-error{{expected string literal as argument of 'diagnose_if' attribute}}
 void failure6(void) _diagnose_if(0, "", "invalid"); // expected-error{{invalid diagnostic type for 'diagnose_if'; use "error" or "warning" instead}}
 void failure7(void) _diagnose_if(0, "", "ERROR"); // expected-error{{invalid diagnostic type}}
 void failure8(int a) _diagnose_if(a, "", ""); // expected-error{{invalid diagnostic type}}
 void failure9(void) _diagnose_if(a, "", ""); // expected-error{{undeclared identifier 'a'}}
 
 int globalVar;
 void never_constant(void) _diagnose_if(globalVar, "", "error"); // expected-error{{'diagnose_if' attribute expression never produces a constant expression}} expected-note{{subexpression not valid}}
 void never_constant(void) _diagnose_if(globalVar, "", "warning"); // expected-error{{'diagnose_if' attribute expression never produces a constant expression}} expected-note{{subexpression not valid}}

clang/test/Sema/enable_if.c

void test5(void) {
   void *p4 = (void *)isdigit2;
 }
 
 #ifndef CODEGEN
 __attribute__((enable_if(n == 0, "chosen when 'n' is zero"))) void f1(int n); // expected-error{{use of undeclared identifier 'n'}}
 
 int n __attribute__((enable_if(1, "always chosen"))); // expected-warning{{'enable_if' attribute only applies to functions}}
 
-void f(int n) __attribute__((enable_if("chosen when 'n' is zero", n == 0)));  // expected-error{{'enable_if' attribute requires a string}}
+void f(int n) __attribute__((enable_if("chosen when 'n' is zero", n == 0)));  // expected-error{{expected string literal as argument of 'enable_if' attribute}}
 
 void f(int n) __attribute__((enable_if()));  // expected-error{{'enable_if' attribute requires exactly 2 arguments}}
 
 void f(int n) __attribute__((enable_if(unresolvedid, "chosen when 'unresolvedid' is non-zero")));  // expected-error{{use of undeclared identifier 'unresolvedid'}}
 
 int global;
 void f(int n) __attribute__((enable_if(global == 0, "chosen when 'global' is zero")));  // expected-error{{'enable_if' attribute expression never produces a constant expression}}  // expected-note{{subexpression not valid in a constant expression}}
 

clang/test/SemaCXX/attr-deprecated-replacement-error.cpp

 // RUN: %clang_cc1 -triple x86_64-apple-darwin9 -verify -fsyntax-only -std=c++11 -fms-extensions %s
 
 #if !__has_feature(attribute_deprecated_with_replacement)
 #error "Missing __has_feature"
 #endif
 
 int a1 [[deprecated("warning", "fixit")]]; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
-int a2 [[deprecated("warning", 1)]]; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
+int a2 [[deprecated("warning", 1)]]; // expected-error{{expected string literal as argument of 'deprecated' attribute}}
 
 int b1 [[gnu::deprecated("warning", "fixit")]]; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
-int b2 [[gnu::deprecated("warning", 1)]]; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
+int b2 [[gnu::deprecated("warning", 1)]]; // expected-error{{expected string literal as argument of 'deprecated' attribute}}
 
 __declspec(deprecated("warning", "fixit")) int c1; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
-__declspec(deprecated("warning", 1)) int c2; // expected-error{{'deprecated' attribute takes no more than 1 argument}}
+__declspec(deprecated("warning", 1)) int c2; // expected-error{{expected string literal as argument of 'deprecated' attribute}}
 
 int d1 __attribute__((deprecated("warning", "fixit")));
-int d2 __attribute__((deprecated("warning", 1))); // expected-error{{'deprecated' attribute requires a string}}
+int d2 __attribute__((deprecated("warning", 1))); // expected-error{{expected string literal as argument of 'deprecated' attribute}}

clang/test/SemaCXX/attr-no-sanitize.cpp

 // RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
 // RUN: not %clang_cc1 -std=c++11 -ast-dump %s | FileCheck --check-prefix=DUMP %s
 // RUN: not %clang_cc1 -std=c++11 -ast-print %s | FileCheck --check-prefix=PRINT %s
 
 int f1() __attribute__((no_sanitize)); // expected-error{{'no_sanitize' attribute takes at least 1 argument}}
 
-int f2() __attribute__((no_sanitize(1))); // expected-error{{'no_sanitize' attribute requires a string}}
+int f2() __attribute__((no_sanitize(1))); // expected-error{{expected string literal as argument of 'no_sanitize' attribute}}
 
 __attribute__((no_sanitize("all"))) int global; // expected-warning{{'no_sanitize' attribute argument 'all' not supported on a global variable}}
 __attribute__((no_sanitize("unknown"))) int global2; // expected-warning{{unknown sanitizer 'unknown' ignored}}
 
 // DUMP-LABEL: FunctionDecl {{.*}} f3
 // DUMP: NoSanitizeAttr {{.*}} address
 // PRINT: int f3() __attribute__((no_sanitize("address")))
 int f3() __attribute__((no_sanitize("address")));

clang/test/SemaCXX/attr-section.cpp

 // RUN: %clang_cc1 -verify -fsyntax-only -triple x86_64-linux-gnu %s
 
 int x __attribute__((section(
-   42)));  // expected-error {{'section' attribute requires a string}}
+   42)));  // expected-error {{expected string literal as argument of 'section' attribute}}
 
 
 // PR6007
 void test() {
   __attribute__((section("NEAR,x"))) int n1; // expected-error {{'section' attribute only applies to functions, global variables, Objective-C methods, and Objective-C properties}}
   __attribute__((section("NEAR,x"))) static int n2; // ok.
 }
 

clang/test/SemaCXX/attr-weakref.cpp

 int a8 __attribute__((weakref ("v1"))); // expected-error {{weakref declaration must have internal linkage}}
 
 // gcc accepts this
 int a9 __attribute__((weakref));  // expected-error {{weakref declaration of 'a9' must also have an alias attribute}}
 
 static int a10();
 int a10() __attribute__((weakref ("foo")));
 
-static int v __attribute__((weakref(a1), alias("foo"))); // expected-error {{'weakref' attribute requires a string}}
+static int v __attribute__((weakref(a1), alias("foo"))); // expected-error {{expected string literal as argument of 'weakref' attribute}}
 
 __attribute__((weakref ("foo"))) auto a11 = 1; // expected-error {{weakref declaration must have internal linkage}}

clang/test/SemaCXX/suppress.cpp

void f_() {
   int *p;
   [[gsl::suppress("type", "bounds")]] {
     p = reinterpret_cast<int *>(7);
   }
 
   [[gsl::suppress]] int x; // expected-error {{'suppress' attribute takes at least 1 argument}}
   [[gsl::suppress()]] int y; // expected-error {{'suppress' attribute takes at least 1 argument}}
   int [[gsl::suppress("r")]] z; // expected-error {{'suppress' attribute cannot be applied to types}}
-  [[gsl::suppress(f_)]] float f; // expected-error {{'suppress' attribute requires a string}}
+  [[gsl::suppress(f_)]] float f; // expected-error {{expected string literal as argument of 'suppress' attribut}}
 }
 
 union [[gsl::suppress("type.1")]] U {
   int i;
   float f;
 };

clang/test/SemaObjC/attr-swift_bridge.m

 // RUN: %clang_cc1 -verify -fsyntax-only %s
 
 // expected-error@+1 {{'__swift_bridge__' attribute takes one argument}}
 __attribute__((__swift_bridge__))
 @interface I
 @end
 
-// expected-error@+1 {{'__swift_bridge__' attribute requires a string}}
+// expected-error@+1 {{expected string literal as argument of '__swift_bridge__' attribute}}
 __attribute__((__swift_bridge__(1)))
 @interface J
 @end
 
 // expected-error@+1 {{'__swift_bridge__' attribute takes one argument}}
 __attribute__((__swift_bridge__("K", 1)))
 @interface K
 @end

clang/test/SemaObjC/objc-asm-attribute-neg-test.m

 // RUN: %clang_cc1  -fsyntax-only -verify -Wno-objc-root-class %s
 // rdar://16462586
 
 __attribute__((objc_runtime_name)) // expected-error {{'objc_runtime_name' attribute takes one argument}}
 @interface BInterface
 @end
 
-__attribute__((objc_runtime_name(123))) // expected-error {{'objc_runtime_name' attribute requires a string}}
+__attribute__((objc_runtime_name(123))) // expected-error {{expected string literal as argument of 'objc_runtime_name' attribute}}
 @protocol BProtocol1
 @end
 
 __attribute__((objc_runtime_name("MySecretNamespace.Protocol")))
 @protocol Protocol
 @end
 
 __attribute__((objc_runtime_name("MySecretNamespace.Message")))
-@interface Message <Protocol> { 
+@interface Message <Protocol> {
 __attribute__((objc_runtime_name("MySecretNamespace.Message"))) // expected-error {{'objc_runtime_name' attribute only applies to Objective-C interfaces and Objective-C protocols}}
   id MyIVAR;
 }
 __attribute__((objc_runtime_name("MySecretNamespace.Message")))
 @property int MyProperty; // expected-error {{prefix attribute must be followed by an interface, protocol, or implementation}}}}
 
 - (int) getMyProperty __attribute__((objc_runtime_name("MySecretNamespace.Message"))); // expected-error {{'objc_runtime_name' attribute only applies to}}
 

clang/test/SemaObjC/validate-attr-swift_attr.m

 // RUN: %clang_cc1 -verify -fsyntax-only %s
 
 // expected-error@+1 {{'swift_attr' attribute takes one argument}}
 __attribute__((swift_attr))
 @interface I
 @end
 
-// expected-error@+1 {{'swift_attr' attribute requires a string}}
+// expected-error@+1 {{expected string literal as argument of 'swift_attr' attribute}}
 __attribute__((swift_attr(1)))
 @interface J
 @end

clang/test/SemaTemplate/attributes.cpp

namespace attribute_aligned {
   check_alignment<3>::t c3; // expected-note 2 {{in instantiation}}
   check_alignment<4>::t c4;
 
   template<unsigned Size, unsigned Align>
   class my_aligned_storage
   {
     __attribute__((aligned(Align))) char storage[Size];
   };
-  
   template<typename T>
   class C {
   public:
     C() {
       static_assert(sizeof(t) == sizeof(T), "my_aligned_storage size wrong");
       static_assert(alignof(t) == alignof(T), "my_aligned_storage align wrong"); // expected-warning{{'alignof' applied to an expression is a GNU extension}}
     }
     

 // CHECK-NEXT:       ConstantExpr {{.*}} 'int'
 // CHECK-NEXT:         value: Int 3
 // CHECK-NEXT:         SubstNonTypeTemplateParmExpr {{.*}} 'int'
 // CHECK-NEXT:           NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 0 index 0 ... Is
 // CHECK-NEXT:           IntegerLiteral {{.*}} 'int' 3
 template <int... Is> [[clang::annotate("ANNOTATE_BAZ", Is...)]] void HasPackAnnotations();
 void UsePackAnnotations() { HasPackAnnotations<1, 2, 3>(); }
 
-template <int... Is> [[clang::annotate(Is...)]] void HasOnlyPackAnnotation() {} // expected-error {{'annotate' attribute takes at least 1 argument}} expected-error {{'annotate' attribute requires a string}}
+template <int... Is> [[clang::annotate(Is...)]] void HasOnlyPackAnnotation() {} // expected-error {{expected string literal as argument of 'annotate' attribute}}
 
 void UseOnlyPackAnnotations() {
-  HasOnlyPackAnnotation<>();  // expected-note {{in instantiation of function template specialization 'attribute_annotate::HasOnlyPackAnnotation<>' requested here}}
-  HasOnlyPackAnnotation<1>(); // expected-note {{in instantiation of function template specialization 'attribute_annotate::HasOnlyPackAnnotation<1>' requested here}}
+  HasOnlyPackAnnotation<>();
+  HasOnlyPackAnnotation<1>();
 }
 
 // CHECK:      ClassTemplateDecl {{.*}} AnnotatedPackTemplateStruct
 // CHECK-NEXT:   TemplateTypeParmDecl {{.*}} typename depth 0 index 0 T
 // CHECK-NEXT:   NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 0 index 1 ... Is
 // CHECK-NEXT:   CXXRecordDecl {{.*}} struct AnnotatedPackTemplateStruct definition
 // CHECK-NEXT:     DefinitionData
 // CHECK-NEXT:       DefaultConstructor

 // CHECK-NEXT:       IntegerLiteral {{.*}} 'int' 4
 // CHECK-NEXT:     ConstantExpr {{.*}} 'int'
 // CHECK-NEXT:       value: Int 5
 // CHECK-NEXT:       IntegerLiteral {{.*}} 'int' 5
 // CHECK-NEXT:     ConstantExpr {{.*}} 'int'
 // CHECK-NEXT:       value: Int 6
 // CHECK-NEXT:       IntegerLiteral {{.*}} 'int' 6
 // CHECK-NEXT:   CXXRecordDecl {{.*}} implicit struct AnnotatedPackTemplateStruct
-// CHECK-NEXT: ClassTemplatePartialSpecializationDecl {{.*}} struct AnnotatedPackTemplateStruct definition
-// CHECK-NEXT:   DefinitionData
-// CHECK-NEXT:     DefaultConstructor
-// CHECK-NEXT:     CopyConstructor
-// CHECK-NEXT:     MoveConstructor
-// CHECK-NEXT:     CopyAssignment
-// CHECK-NEXT:     MoveAssignment
-// CHECK-NEXT:     Destructor
-// CHECK-NEXT:   TemplateArgument{{.*}} type 'char'
-// CHECK-NEXT:     BuiltinType {{.*}} 'char'
-// CHECK-NEXT:   TemplateArgument{{.*}} pack
-// CHECK-NEXT:     TemplateArgument{{.*}} expr
-// CHECK-NEXT:       PackExpansionExpr {{.*}} 'int'
-// CHECK-NEXT:         DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'Is' 'int'
-// CHECK-NEXT:   NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 0 index 0 ... Is
-// CHECK-NEXT:   AnnotateAttr {{.*}} ""
-// CHECK-NEXT:     PackExpansionExpr {{.*}} '<dependent type>'
-// CHECK-NEXT:       DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'Is' 'int'
-// CHECK-NEXT:   CXXRecordDecl {{.*}} implicit struct AnnotatedPackTemplateStruct
 template <typename T, int... Is> struct [[clang::annotate("ANNOTATE_FOZ", Is...)]] AnnotatedPackTemplateStruct{};
 template <int... Is> struct [[clang::annotate("ANNOTATE_BOO", Is...)]] AnnotatedPackTemplateStruct<int, Is...>{};
 template <int... Is> struct [[clang::annotate("ANNOTATE_FOZ", 4, 5, 6)]] AnnotatedPackTemplateStruct<float, Is...>{};
-template <int... Is> struct [[clang::annotate(Is...)]] AnnotatedPackTemplateStruct<char, Is...>{}; // expected-error {{'annotate' attribute requires a string}} expected-error {{'annotate' attribute takes at least 1 argument}}
+template <int... Is> struct [[clang::annotate(Is...)]] AnnotatedPackTemplateStruct<char, Is...>{}; // expected-error {{expected string literal as argument of 'annotate' attribute}}
 void UseAnnotatedPackTemplateStructSpecializations() {
   AnnotatedPackTemplateStruct<int, 1, 2, 3> Instance1{};
   AnnotatedPackTemplateStruct<float, 3, 2, 1> Instance2{};
   AnnotatedPackTemplateStruct<bool, 7, 8, 9> Instance3{};
-  AnnotatedPackTemplateStruct<char, 1, 2, 3> Instance4{}; // expected-note {{in instantiation of template class 'attribute_annotate::AnnotatedPackTemplateStruct<char, 1, 2, 3>' requested here}}
-  AnnotatedPackTemplateStruct<char> Instance5{};          // expected-note {{in instantiation of template class 'attribute_annotate::AnnotatedPackTemplateStruct<char>' requested here}}
+  AnnotatedPackTemplateStruct<char, 1, 2, 3> Instance4{};
+  AnnotatedPackTemplateStruct<char> Instance5{};
 }
 
 // CHECK:      ClassTemplateDecl {{.*}} InvalidAnnotatedPackTemplateStruct
 // CHECK-NEXT:   TemplateTypeParmDecl {{.*}} typename depth 0 index 0 T
-// CHECK-NEXT:   NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 0 index 1 ... Is
+// CHECK-NEXT:   NonTypeTemplateParmDecl {{.*}} 'int' depth 0 index 1 ... Is
 // CHECK-NEXT:   CXXRecordDecl {{.*}} struct InvalidAnnotatedPackTemplateStruct definition
 // CHECK-NEXT:     DefinitionData
 // CHECK-NEXT:       DefaultConstructor
 // CHECK-NEXT:       CopyConstructor
 // CHECK-NEXT:       MoveConstructor
 // CHECK-NEXT:       CopyAssignment
 // CHECK-NEXT:       MoveAssignment
 // CHECK-NEXT:       Destructor
-// CHECK-NEXT:     AnnotateAttr {{.*}} ""
-// CHECK-NEXT:       PackExpansionExpr {{.*}} '<dependent type>'
-// CHECK-NEXT:         DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'Is' 'int'
 // CHECK-NEXT:     CXXRecordDecl {{.*}} implicit struct InvalidAnnotatedPackTemplateStruct
 // CHECK-NEXT:   ClassTemplateSpecialization {{.*}} 'InvalidAnnotatedPackTemplateStruct'
 // CHECK-NEXT:   ClassTemplateSpecializationDecl {{.*}} struct InvalidAnnotatedPackTemplateStruct definition
 // CHECK-NEXT:     DefinitionData
 // CHECK-NEXT:       DefaultConstructor
 // CHECK-NEXT:       CopyConstructor
 // CHECK-NEXT:       MoveConstructor
 // CHECK-NEXT:       CopyAssignment

 // CHECK-NEXT:     Destructor
 // CHECK-NEXT:   TemplateArgument{{.*}} type 'char'
 // CHECK-NEXT:     BuiltinType {{.*}} 'char'
 // CHECK-NEXT:   TemplateArgument{{.*}} pack
 // CHECK-NEXT:     TemplateArgument{{.*}} integral 5
 // CHECK-NEXT:     TemplateArgument{{.*}} integral 6
 // CHECK-NEXT:     TemplateArgument{{.*}} integral 7
 // CHECK-NEXT:   CXXRecordDecl {{.*}} implicit struct InvalidAnnotatedPackTemplateStruct
-template <typename T, int... Is> struct [[clang::annotate(Is...)]] InvalidAnnotatedPackTemplateStruct{}; // expected-error {{'annotate' attribute requires a string}} expected-error {{'annotate' attribute takes at least 1 argument}}
+template <typename T, int... Is> struct InvalidAnnotatedPackTemplateStruct{};
 template <int... Is> struct [[clang::annotate("ANNOTATE_BIR", Is...)]] InvalidAnnotatedPackTemplateStruct<int, Is...>{};
 template <int... Is> struct InvalidAnnotatedPackTemplateStruct<float, Is...> {};
 template <> struct InvalidAnnotatedPackTemplateStruct<char, 5, 6, 7> {};
 void UseInvalidAnnotatedPackTemplateStruct() {
   InvalidAnnotatedPackTemplateStruct<int, 1, 2, 3> Instance1{};
   InvalidAnnotatedPackTemplateStruct<float, 3, 2, 1> Instance2{};
   InvalidAnnotatedPackTemplateStruct<char, 5, 6, 7> Instance3{};
-  InvalidAnnotatedPackTemplateStruct<bool, 7, 8, 9> Instance4{}; // expected-note {{in instantiation of template class 'attribute_annotate::InvalidAnnotatedPackTemplateStruct<bool, 7, 8, 9>' requested here}}
-  InvalidAnnotatedPackTemplateStruct<bool> Instance5{};          // expected-note {{in instantiation of template class 'attribute_annotate::InvalidAnnotatedPackTemplateStruct<bool>' requested here}}
+  InvalidAnnotatedPackTemplateStruct<bool, 7, 8, 9> Instance4{};
+  InvalidAnnotatedPackTemplateStruct<bool> Instance5{};
 }
 
 // CHECK:      FunctionTemplateDecl {{.*}} RedeclaredAnnotatedFunc
 // CHECK-NEXT:   NonTypeTemplateParmDecl {{.*}} referenced 'int' depth 0 index 0 ... Is
 // CHECK-NEXT:   FunctionDecl {{.*}} RedeclaredAnnotatedFunc 'void ()'
 // CHECK-NEXT:     AnnotateAttr {{.*}} "ANNOTATE_FAR"
 // CHECK-NEXT:       PackExpansionExpr {{.*}} '<dependent type>'
 // CHECK-NEXT:         DeclRefExpr {{.*}} 'int' NonTypeTemplateParm {{.*}} 'Is' 'int'

clang/utils/TableGen/ClangAttrEmitter.cpp

 static bool isVariadicExprArgument(const Record *Arg) {
   return !Arg->getSuperClasses().empty() &&
          llvm::StringSwitch<bool>(
              Arg->getSuperClasses().back().first->getName())
              .Case("VariadicExprArgument", true)
              .Default(false);
 }
 
+static bool isStringLiteralArgument(const Record *Arg) {
+  return !Arg->getSuperClasses().empty() &&
+         llvm::StringSwitch<bool>(
+             Arg->getSuperClasses().back().first->getName())
+             .Case("StringArgument", true)
+             .Default(false);
+}
+
+static bool isVariadicStringLiteralArgument(const Record *Arg) {
+  return !Arg->getSuperClasses().empty() &&
+         llvm::StringSwitch<bool>(
+             Arg->getSuperClasses().back().first->getName())
+             .Case("VariadicStringArgument", true)
+             .Default(false);
+}
+
 static void emitClangAttrVariadicIdentifierArgList(RecordKeeper &Records,
                                                    raw_ostream &OS) {
   OS << "#if defined(CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST)\n";
   std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
   for (const auto *A : Attrs) {
     // Determine whether the first argument is a variadic identifier.
     std::vector<Record *> Args = A->getValueAsListOfDefs("Args");
     if (Args.empty() || !isVariadicIdentifierArgument(Args[0]))
       continue;
 
     // All these spellings take an identifier argument.
     forEachUniqueSpelling(*A, [&](const FlattenedSpelling &S) {
       OS << ".Case(\"" << S.name() << "\", "
          << "true"
          << ")\n";
     });
   }
   OS << "#endif // CLANG_ATTR_VARIADIC_IDENTIFIER_ARG_LIST\n\n";
 }
 
+// Emits the list of arguments that shoulkd be parsed as unevaluated string
+// literals for each attributes
+static void emitClangAttrUnevaluatedStringLiteralList(RecordKeeper &Records,
+                                                      raw_ostream &OS) {
+  OS << "#if defined(CLANG_ATTR_STRING_LITERAL_ARG_LIST)\n";
+  std::vector<Record *> Attrs = Records.getAllDerivedDefinitions("Attr");
+  for (const auto *Attr : Attrs) {
+    std::vector<Record *> Args = Attr->getValueAsListOfDefs("Args");
+    uint32_t Bits = 0;
+    for (uint32_t N = 0; N < Args.size(); N++) {
+      Bits |= (isStringLiteralArgument(Args[N]) << N);
+      // If we have a variadic string argument, set all the remaining bits to 1
+      if (isVariadicStringLiteralArgument(Args[N])) {
+        for (; N < sizeof(uint32_t); N++)
+          Bits |= (1 << N);
+        break;
+      }
+    }
+    if (!Bits)
+      continue;
+    // All these spellings have at least one string literal has argument.
+    forEachUniqueSpelling(*Attr, [&](const FlattenedSpelling &S) {
+      OS << ".Case(\"" << S.name() << "\", " << Bits << ")\n";
+    });
+  }
+  OS << "#endif // CLANG_ATTR_STRING_LITERAL_ARG_LIST\n\n";
+}
+
 // Emits the first-argument-is-identifier property for attributes.
 static void emitClangAttrIdentifierArgList(RecordKeeper &Records, raw_ostream &OS) {
   OS << "#if defined(CLANG_ATTR_IDENTIFIER_ARG_LIST)\n";
   std::vector<Record*> Attrs = Records.getAllDerivedDefinitions("Attr");
 
   for (const auto *Attr : Attrs) {
     // Determine whether the first argument is an identifier.
     std::vector<Record *> Args = Attr->getValueAsListOfDefs("Args");
void EmitClangAttrNodeTraverse(RecordKeeper &Records, raw_ostream &OS) {
   }
 }
 
 void EmitClangAttrParserStringSwitches(RecordKeeper &Records,
                                        raw_ostream &OS) {
   emitSourceFileHeader("Parser-related llvm::StringSwitch cases", OS);
   emitClangAttrArgContextList(Records, OS);
   emitClangAttrIdentifierArgList(Records, OS);
+  emitClangAttrUnevaluatedStringLiteralList(Records, OS);
   emitClangAttrVariadicIdentifierArgList(Records, OS);
   emitClangAttrThisIsaIdentifierArgList(Records, OS);
   emitClangAttrAcceptsExprPack(Records, OS);
   emitClangAttrTypeArgList(Records, OS);
   emitClangAttrLateParsedList(Records, OS);
 }
 
 void EmitClangAttrSubjectMatchRulesParserStringSwitches(RecordKeeper &Records,

clang/www/cxx_status.html

  <tr>
   <td>Making non-encodable string literals ill-formed</td>
   <td><a href="https://wg21.link/P1854R4">P1854R4</a> (<a href="#dr">DR</a>)</td>
   <td class="full" align="center">Clang 14</td>
  </tr>
  <tr>
   <td>Unevaluated strings</td>
   <td><a href="https://wg21.link/P2361R6">P2361R6</a></td>
-  <td class="partial" align="center">
-    <details>
-      <summary>Clang 17 (Partial)</summary>
-      Attributes arguments don't yet parse as unevaluated string literals.
-    </details>
-  </td>
+  <td class="unreleased" align="center">Clang 18</td>
  </tr>
  <tr>
   <td>Add @, $, and ` to the basic character set</td>
   <td><a href="https://wg21.link/P2558R2">P2558R2</a></td>
   <td class="full" align="center">Yes</td>
  </tr>
  <tr>
   <td>constexpr cast from <tt>void*</tt></td>