[Clang][C++26] Remove the notion of replaceability.

clang-tools-extra/clang-tidy/modernize/TypeTraitsCheck.cpp

@@ -83,7 +83,6 @@ static const llvm::StringSet<> ValueTraits = {
     "is_pointer_interconvertible_base_of",
     "is_polymorphic",
     "is_reference",
-    "is_replaceable",
     "is_rvalue_reference",
     "is_same",
     "is_scalar",

clang/docs/LanguageExtensions.rst

@@ -2044,8 +2044,6 @@ The following type trait primitives are supported by Clang. Those traits marked
   is trivially relocatable, as defined by the C++26 standard [meta.unary.prop].
   Note that when relocating the caller code should ensure that if the object is polymorphic,
   the dynamic type is of the most derived type. Padding bytes should not be copied.
-* ``__builtin_is_replaceable`` (C++): Returns true if an object
-  is replaceable, as defined by the C++26 standard [meta.unary.prop].
 * ``__is_trivially_equality_comparable`` (Clang): Returns true if comparing two
   objects of the provided type is known to be equivalent to comparing their
   object representations. Note that types containing padding bytes are never

clang/include/clang/AST/ASTContext.h

@@ -666,7 +666,6 @@ class ASTContext : public RefCountedBase<ASTContext> {
 public:
   struct CXXRecordDeclRelocationInfo {
     unsigned IsRelocatable;
-    unsigned IsReplaceable;
   };
   std::optional<CXXRecordDeclRelocationInfo>
   getRelocationInfoForCXXRecord(const CXXRecordDecl *) const;

clang/include/clang/Basic/Attr.td

@@ -1952,14 +1952,6 @@ def TriviallyRelocatable : InheritableAttr {
   let Documentation = [InternalOnly];
 }
 
-def Replaceable : InheritableAttr {
-  let Spellings = [CustomKeyword<"replaceable_if_eligible">];
-  let SemaHandler = 0;
-  // Omitted from docs, since this is language syntax, not an attribute, as far
-  // as users are concerned.
-  let Documentation = [InternalOnly];
-}
-
 def MinSize : InheritableAttr {
   let Spellings = [Clang<"minsize">];
   let Subjects = SubjectList<[Function, ObjCMethod], ErrorDiag>;

clang/include/clang/Basic/DiagnosticParseKinds.td

@@ -1077,23 +1077,24 @@ def ext_ms_abstract_keyword : ExtWarn<
   "'abstract' keyword is a Microsoft extension">,
   InGroup<MicrosoftAbstract>;
 
-def ext_relocatable_keyword : ExtWarn<
-  "'%select{trivially_relocatable_if_eligible|replaceable_if_eligible}0' "
-  "keyword is a C++2c extension">,
-  InGroup<CXX26>;
-def warn_relocatable_keyword  : Warning<
-  "'%select{trivially_relocatable|replaceable}0_if_eligible' "
-  "keyword is incompatible with standards before C++2c">,
-  DefaultIgnore, InGroup<CXXPre26Compat>;
+def ext_relocatable_keyword
+    : ExtWarn<
+          "'trivially_relocatable_if_eligible' keyword is a C++2c extension">,
+      InGroup<CXX26>;
+def warn_relocatable_keyword
+    : Warning<"'trivially_relocatable_if_eligible' keyword is incompatible "
+              "with standards before C++2c">,
+      DefaultIgnore,
+      InGroup<CXXPre26Compat>;
 
 def err_access_specifier_interface : Error<
   "interface types cannot specify '%select{private|protected}0' access">;
 
 def err_duplicate_class_virt_specifier : Error<
   "class already marked '%0'">;
 
-def err_duplicate_class_relocation_specifier : Error<
-  "class already marked '%select{trivially_relocatable_if_eligible|replaceable_if_eligible}0'">;
+def err_duplicate_class_relocation_specifier
+    : Error<"class already marked 'trivially_relocatable_if_eligible'">;
 
 def err_duplicate_virt_specifier : Error<
   "class member already marked '%0'">;

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -1770,7 +1770,6 @@ def err_user_defined_msg_constexpr : Error<
 def note_unsatisfied_trait
     : Note<"%0 is not %enum_select<TraitName>{"
            "%TriviallyRelocatable{trivially relocatable}|"
-           "%Replaceable{replaceable}|"
            "%TriviallyCopyable{trivially copyable}|"
            "%Empty{empty}|"
            "%StandardLayout{standard-layout}|"
@@ -1792,8 +1791,6 @@ def note_unsatisfied_trait_reason
            "class type}|"
            "%NTRBase{has a non-trivially-relocatable base %1}|"
            "%NTRField{has a non-trivially-relocatable member %1 of type %2}|"
-           "%NonReplaceableBase{has a non-replaceable base %1}|"
-           "%NonReplaceableField{has a non-replaceable member %1 of type %2}|"
            "%NTCBase{has a non-trivially-copyable base %1}|"
            "%NTCField{has a non-trivially-copyable member %1 of type %2}|"
            "%NonEmptyMember{has a non-static data member %1 of type %2}|"

clang/include/clang/Basic/TokenKinds.def

@@ -564,7 +564,6 @@ TYPE_TRAIT_2(/*EmptySpellingName*/, IsDeducible, KEYCXX)
 TYPE_TRAIT_1(__builtin_is_cpp_trivially_relocatable, IsCppTriviallyRelocatable, KEYCXX)
 TYPE_TRAIT_1(__is_trivially_relocatable, IsTriviallyRelocatable, KEYCXX)
 TYPE_TRAIT_1(__is_bitwise_cloneable, IsBitwiseCloneable, KEYALL)
-TYPE_TRAIT_1(__builtin_is_replaceable, IsReplaceable, KEYCXX)
 TYPE_TRAIT_1(__builtin_structured_binding_size, StructuredBindingSize, KEYCXX)
 
 

clang/include/clang/Parse/Parser.h

@@ -2835,7 +2835,6 @@ class Parser : public CodeCompletionHandler {
   mutable IdentifierInfo *Ident_GNU_final;
   mutable IdentifierInfo *Ident_override;
   mutable IdentifierInfo *Ident_trivially_relocatable_if_eligible;
-  mutable IdentifierInfo *Ident_replaceable_if_eligible;
 
   /// Representation of a class that has been parsed, including
   /// any member function declarations or definitions that need to be
@@ -3129,7 +3128,7 @@ class Parser : public CodeCompletionHandler {
 
   /// isClassCompatibleKeyword - Determine whether the next token is a C++11
   /// 'final', a C++26 'trivially_relocatable_if_eligible',
-  /// 'replaceable_if_eligible', or Microsoft 'sealed' or 'abstract' contextual
+  /// or Microsoft 'sealed' or 'abstract' contextual
   /// keyword.
   bool isClassCompatibleKeyword() const;
 
@@ -3603,12 +3602,8 @@ class Parser : public CodeCompletionHandler {
   bool isCXX2CTriviallyRelocatableKeyword() const;
   void ParseCXX2CTriviallyRelocatableSpecifier(SourceLocation &TRS);
 
-  bool isCXX2CReplaceableKeyword(Token Tok) const;
-  bool isCXX2CReplaceableKeyword() const;
-  void ParseCXX2CReplaceableSpecifier(SourceLocation &MRS);
-
   /// 'final', a C++26 'trivially_relocatable_if_eligible',
-  /// 'replaceable_if_eligible', or Microsoft 'sealed' or 'abstract' contextual
+  /// or Microsoft 'sealed' or 'abstract' contextual
   /// keyword.
   bool isClassCompatibleKeyword(Token Tok) const;
 

clang/include/clang/Sema/Sema.h

@@ -4366,7 +4366,6 @@ class Sema final : public SemaBase {
                                        bool IsFinalSpelledSealed,
                                        bool IsAbstract,
                                        SourceLocation TriviallyRelocatable,
-                                       SourceLocation Replaceable,
                                        SourceLocation LBraceLoc);
 
   /// ActOnTagFinishDefinition - Invoked once we have finished parsing
@@ -4375,7 +4374,7 @@ class Sema final : public SemaBase {
                                 SourceRange BraceRange);
 
   ASTContext::CXXRecordDeclRelocationInfo
-  CheckCXX2CRelocatableAndReplaceable(const clang::CXXRecordDecl *D);
+  CheckCXX2CRelocatable(const clang::CXXRecordDecl *D);
 
   void ActOnTagFinishSkippedDefinition(SkippedDefinitionContext Context);
 
@@ -8733,12 +8732,6 @@ class Sema final : public SemaBase {
   bool IsCXXTriviallyRelocatableType(QualType T);
   bool IsCXXTriviallyRelocatableType(const CXXRecordDecl &RD);
 
-  //// Determines if a type is replaceable
-  /// according to the C++26 rules.
-  // FIXME: This is in Sema because it requires
-  // overload resolution, can we move to ASTContext?
-  bool IsCXXReplaceableType(QualType T);
-
   /// Check the operands of ?: under C++ semantics.
   ///
   /// See C++ [expr.cond]. Note that LHS is never null, even for the GNU x ?: y

clang/lib/Parse/ParseDeclCXX.cpp

@@ -2498,40 +2498,13 @@ void Parser::ParseCXX2CTriviallyRelocatableSpecifier(SourceLocation &TRS) {
 
   Diag(Tok.getLocation(), getLangOpts().CPlusPlus26
                               ? diag::warn_relocatable_keyword
-                              : diag::ext_relocatable_keyword)
-      << /*relocatable*/ 0;
+                              : diag::ext_relocatable_keyword);
 
   TRS = ConsumeToken();
 }
 
-bool Parser::isCXX2CReplaceableKeyword(Token Tok) const {
-  if (!getLangOpts().CPlusPlus || Tok.isNot(tok::identifier))
-    return false;
-  if (!Ident_replaceable_if_eligible)
-    Ident_replaceable_if_eligible =
-        &PP.getIdentifierTable().get("replaceable_if_eligible");
-  IdentifierInfo *II = Tok.getIdentifierInfo();
-  return II == Ident_replaceable_if_eligible;
-}
-
-bool Parser::isCXX2CReplaceableKeyword() const {
-  return isCXX2CReplaceableKeyword(Tok);
-}
-
-void Parser::ParseCXX2CReplaceableSpecifier(SourceLocation &MRS) {
-  assert(isCXX2CReplaceableKeyword() &&
-         "expected a replaceable_if_eligible specifier");
-
-  Diag(Tok.getLocation(), getLangOpts().CPlusPlus26
-                              ? diag::warn_relocatable_keyword
-                              : diag::ext_relocatable_keyword)
-      << /*replaceable*/ 1;
-
-  MRS = ConsumeToken();
-}
-
 bool Parser::isClassCompatibleKeyword(Token Tok) const {
-  if (isCXX2CTriviallyRelocatableKeyword(Tok) || isCXX2CReplaceableKeyword(Tok))
+  if (isCXX2CTriviallyRelocatableKeyword(Tok))
     return true;
   VirtSpecifiers::Specifier Specifier = isCXX11VirtSpecifier(Tok);
   return Specifier == VirtSpecifiers::VS_Final ||
@@ -3587,7 +3560,6 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
   bool IsFinalSpelledSealed = false;
   bool IsAbstract = false;
   SourceLocation TriviallyRelocatable;
-  SourceLocation Replaceable;
 
   // Parse the optional 'final' keyword.
   if (getLangOpts().CPlusPlus && Tok.is(tok::identifier)) {
@@ -3599,23 +3571,12 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
             auto Skipped = Tok;
             ConsumeToken();
             Diag(Skipped, diag::err_duplicate_class_relocation_specifier)
-                << /*trivial_relocatable*/ 0 << TriviallyRelocatable;
+                << TriviallyRelocatable;
           } else {
             ParseCXX2CTriviallyRelocatableSpecifier(TriviallyRelocatable);
           }
           continue;
         }
-        if (isCXX2CReplaceableKeyword(Tok)) {
-          if (Replaceable.isValid()) {
-            auto Skipped = Tok;
-            ConsumeToken();
-            Diag(Skipped, diag::err_duplicate_class_relocation_specifier)
-                << /*replaceable*/ 1 << Replaceable;
-          } else {
-            ParseCXX2CReplaceableSpecifier(Replaceable);
-          }
-          continue;
-        }
         break;
       }
       if (isCXX11FinalKeyword()) {
@@ -3654,7 +3615,7 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
         Diag(FinalLoc, diag::ext_warn_gnu_final);
     }
     assert((FinalLoc.isValid() || AbstractLoc.isValid() ||
-            TriviallyRelocatable.isValid() || Replaceable.isValid()) &&
+            TriviallyRelocatable.isValid()) &&
            "not a class definition");
 
     // Parse any C++11 attributes after 'final' keyword.
@@ -3729,7 +3690,7 @@ void Parser::ParseCXXMemberSpecification(SourceLocation RecordLoc,
   if (TagDecl)
     Actions.ActOnStartCXXMemberDeclarations(
         getCurScope(), TagDecl, FinalLoc, IsFinalSpelledSealed, IsAbstract,
-        TriviallyRelocatable, Replaceable, T.getOpenLocation());
+        TriviallyRelocatable, T.getOpenLocation());
 
   // C++ 11p3: Members of a class defined with the keyword class are private
   // by default. Members of a class defined with the keywords struct or union

clang/lib/Parse/Parser.cpp

@@ -515,7 +515,6 @@ void Parser::Initialize() {
   Ident_abstract = nullptr;
   Ident_override = nullptr;
   Ident_trivially_relocatable_if_eligible = nullptr;
-  Ident_replaceable_if_eligible = nullptr;
   Ident_GNU_final = nullptr;
   Ident_import = nullptr;
   Ident_module = nullptr;

clang/lib/Sema/SemaDecl.cpp

@@ -18794,10 +18794,12 @@ bool Sema::ActOnDuplicateDefinition(Scope *S, Decl *Prev,
   return true;
 }
 
-void Sema::ActOnStartCXXMemberDeclarations(
-    Scope *S, Decl *TagD, SourceLocation FinalLoc, bool IsFinalSpelledSealed,
-    bool IsAbstract, SourceLocation TriviallyRelocatable,
-    SourceLocation Replaceable, SourceLocation LBraceLoc) {
+void Sema::ActOnStartCXXMemberDeclarations(Scope *S, Decl *TagD,
+                                           SourceLocation FinalLoc,
+                                           bool IsFinalSpelledSealed,
+                                           bool IsAbstract,
+                                           SourceLocation TriviallyRelocatable,
+                                           SourceLocation LBraceLoc) {
   AdjustDeclIfTemplate(TagD);
   CXXRecordDecl *Record = cast<CXXRecordDecl>(TagD);
 
@@ -18820,9 +18822,6 @@ void Sema::ActOnStartCXXMemberDeclarations(
     Record->addAttr(
         TriviallyRelocatableAttr::Create(Context, TriviallyRelocatable));
 
-  if (Replaceable.isValid())
-    Record->addAttr(ReplaceableAttr::Create(Context, Replaceable));
-
   // C++ [class]p2:
   //   [...] The class-name is also inserted into the scope of the
   //   class itself; this is known as the injected-class-name. For