[clang] Use -std=c++23 instead of -std=c++2b

During the ISO C++ Committee meeting plenary session the C++23 Standard
has been voted as technical complete.

This updates the reference to c++2b to c++23 and updates the __cplusplus
macro.

Drive-by fixes c++1z -> c++17 and c++2a -> c++20 when seen.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D149553

23 files changed, 77 insertions, 73 deletions

diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 49572b0..03eb5df 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -5043,7 +5043,7 @@ static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
 
 static bool CheckLocalVariableDeclaration(EvalInfo &Info, const VarDecl *VD) {
   // An expression E is a core constant expression unless the evaluation of E
-  // would evaluate one of the following: [C++2b] - a control flow that passes
+  // would evaluate one of the following: [C++23] - a control flow that passes
   // through a declaration of a variable with static or thread storage duration
   // unless that variable is usable in constant expressions.
   if (VD->isLocalVarDecl() && VD->isStaticLocal() &&
diff --git a/clang/lib/Basic/LangOptions.cpp b/clang/lib/Basic/LangOptions.cpp
index f22fe9a..1abbaa9 100644
--- a/clang/lib/Basic/LangOptions.cpp
+++ b/clang/lib/Basic/LangOptions.cpp
@@ -117,7 +117,7 @@ void LangOptions::setLangDefaults(LangOptions &Opts, Language Lang,
   Opts.CPlusPlus14 = Std.isCPlusPlus14();
   Opts.CPlusPlus17 = Std.isCPlusPlus17();
   Opts.CPlusPlus20 = Std.isCPlusPlus20();
-  Opts.CPlusPlus2b = Std.isCPlusPlus2b();
+  Opts.CPlusPlus23 = Std.isCPlusPlus23();
   Opts.GNUMode = Std.isGNUMode();
   Opts.GNUCVersion = 0;
   Opts.HexFloats = Std.hasHexFloats();
diff --git a/clang/lib/Basic/Targets/OSTargets.cpp b/clang/lib/Basic/Targets/OSTargets.cpp
index 763235f..627bc91 100644
--- a/clang/lib/Basic/Targets/OSTargets.cpp
+++ b/clang/lib/Basic/Targets/OSTargets.cpp
@@ -214,7 +214,8 @@ static void addVisualCDefines(const LangOptions &Opts, MacroBuilder &Builder) {
       Builder.defineMacro("_HAS_CHAR16_T_LANGUAGE_SUPPORT", Twine(1));
 
     if (Opts.isCompatibleWithMSVC(LangOptions::MSVC2015)) {
-      if (Opts.CPlusPlus2b)
+      if (Opts.CPlusPlus23)
+        // TODO update to the proper value.
         Builder.defineMacro("_MSVC_LANG", "202004L");
       else if (Opts.CPlusPlus20)
         Builder.defineMacro("_MSVC_LANG", "202002L");
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 5091917..a2deb9b 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1395,8 +1395,9 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   const Arg *Std = Args.getLastArg(options::OPT_std_EQ);
   ModulesModeCXX20 =
       !Args.hasArg(options::OPT_fmodules) && Std &&
-      (Std->containsValue("c++20") || Std->containsValue("c++2b") ||
-       Std->containsValue("c++2a") || Std->containsValue("c++latest"));
+      (Std->containsValue("c++20") || Std->containsValue("c++2a") ||
+       Std->containsValue("c++23") || Std->containsValue("c++2b") ||
+       Std->containsValue("c++latest"));
 
   // Process -fmodule-header{=} flags.
   if (Arg *A = Args.getLastArg(options::OPT_fmodule_header_EQ,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 5b93b84..32ba560 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3673,7 +3673,8 @@ static bool RenderModulesOptions(Compilation &C, const Driver &D,
   bool HaveStdCXXModules =
       IsCXX && Std &&
       (Std->containsValue("c++2a") || Std->containsValue("c++20") ||
-       Std->containsValue("c++2b") || Std->containsValue("c++latest"));
+       Std->containsValue("c++2b") || Std->containsValue("c++23") ||
+       Std->containsValue("c++latest"));
   bool HaveModules = HaveStdCXXModules;
 
   // -fmodules enables the use of precompiled modules (off by default).
@@ -6637,7 +6638,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                              .Case("c++14", "-std=c++14")
                              .Case("c++17", "-std=c++17")
                              .Case("c++20", "-std=c++20")
-                             .Case("c++latest", "-std=c++2b")
+                             // TODO add c++23 when MSVC supports it.
+                             .Case("c++latest", "-std=c++23")
                              .Default("");
       if (LanguageStandard.empty())
         D.Diag(clang::diag::warn_drv_unused_argument)
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 0b39dd1..0c4e73e 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -452,7 +452,7 @@ static void InitializeStandardPredefinedMacros(const TargetInfo &TI,
   } else {
     //   -- __cplusplus
     // FIXME: Use correct value for C++23.
-    if (LangOpts.CPlusPlus2b)
+    if (LangOpts.CPlusPlus23)
       Builder.defineMacro("__cplusplus", "202101L");
     //      [C++20] The integer literal 202002L.
     else if (LangOpts.CPlusPlus20)
@@ -606,7 +606,7 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     Builder.defineMacro("__cpp_unicode_literals", "200710L");
     Builder.defineMacro("__cpp_user_defined_literals", "200809L");
     Builder.defineMacro("__cpp_lambdas", "200907L");
-    Builder.defineMacro("__cpp_constexpr", LangOpts.CPlusPlus2b   ? "202211L"
+    Builder.defineMacro("__cpp_constexpr", LangOpts.CPlusPlus23   ? "202211L"
                                            : LangOpts.CPlusPlus20 ? "201907L"
                                            : LangOpts.CPlusPlus17 ? "201603L"
                                            : LangOpts.CPlusPlus14 ? "201304L"
@@ -690,15 +690,15 @@ static void InitializeCPlusPlusFeatureTestMacros(const LangOptions &LangOpts,
     //Builder.defineMacro("__cpp_modules", "201907L");
     Builder.defineMacro("__cpp_using_enum", "201907L");
   }
-  // C++2b features.
-  if (LangOpts.CPlusPlus2b) {
+  // C++23 features.
+  if (LangOpts.CPlusPlus23) {
     Builder.defineMacro("__cpp_implicit_move", "202011L");
     Builder.defineMacro("__cpp_size_t_suffix", "202011L");
     Builder.defineMacro("__cpp_if_consteval", "202106L");
     Builder.defineMacro("__cpp_multidimensional_subscript", "202211L");
   }
 
-  // We provide those C++2b features as extensions in earlier language modes, so
+  // We provide those C++23 features as extensions in earlier language modes, so
   // we also define their feature test macros.
   if (LangOpts.CPlusPlus11)
     Builder.defineMacro("__cpp_static_call_operator", "202207L");
diff --git a/clang/lib/Headers/stdatomic.h b/clang/lib/Headers/stdatomic.h
index 48b3ab9..aed33d4 100644
--- a/clang/lib/Headers/stdatomic.h
+++ b/clang/lib/Headers/stdatomic.h
@@ -49,7 +49,7 @@ extern "C" {
    in C2x mode; switch to the correct values once they've been published. */
 #if (defined(__STDC_VERSION__) && __STDC_VERSION__ < 202000L) ||               \
     defined(__cplusplus)
-/* ATOMIC_VAR_INIT was removed in C2x, but still remains in C++2b. */
+/* ATOMIC_VAR_INIT was removed in C2x, but still remains in C++23. */
 #define ATOMIC_VAR_INIT(value) (value)
 #endif
 
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 1b00f7c..82f65ef 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -3348,8 +3348,8 @@ std::optional<uint32_t> Lexer::tryReadNumericUCN(const char *&StartPtr,
   }
 
   if (Delimited && PP) {
-    Diag(SlashLoc, PP->getLangOpts().CPlusPlus2b
-                       ? diag::warn_cxx2b_delimited_escape_sequence
+    Diag(SlashLoc, PP->getLangOpts().CPlusPlus23
+                       ? diag::warn_cxx23_delimited_escape_sequence
                        : diag::ext_delimited_escape_sequence)
         << /*delimited*/ 0 << (PP->getLangOpts().CPlusPlus ? 1 : 0);
   }
@@ -3436,8 +3436,8 @@ std::optional<uint32_t> Lexer::tryReadNamedUCN(const char *&StartPtr,
   }
 
   if (Diagnose && Match)
-    Diag(SlashLoc, PP->getLangOpts().CPlusPlus2b
-                       ? diag::warn_cxx2b_delimited_escape_sequence
+    Diag(SlashLoc, PP->getLangOpts().CPlusPlus23
+                       ? diag::warn_cxx23_delimited_escape_sequence
                        : diag::ext_delimited_escape_sequence)
         << /*named*/ 1 << (PP->getLangOpts().CPlusPlus ? 1 : 0);
 
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 9cc0215..c066e1d 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -312,7 +312,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
           << tok::r_brace;
     else if (!HadError) {
       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
-           Features.CPlusPlus2b ? diag::warn_cxx2b_delimited_escape_sequence
+           Features.CPlusPlus23 ? diag::warn_cxx23_delimited_escape_sequence
                                 : diag::ext_delimited_escape_sequence)
           << /*delimited*/ 0 << (Features.CPlusPlus ? 1 : 0);
     }
@@ -641,7 +641,7 @@ static bool ProcessUCNEscape(const char *ThisTokBegin, const char *&ThisTokBuf,
 
   if ((IsDelimitedEscapeSequence || IsNamedEscapeSequence) && Diags)
     Diag(Diags, Features, Loc, ThisTokBegin, UcnBegin, ThisTokBuf,
-         Features.CPlusPlus2b ? diag::warn_cxx2b_delimited_escape_sequence
+         Features.CPlusPlus23 ? diag::warn_cxx23_delimited_escape_sequence
                               : diag::ext_delimited_escape_sequence)
         << (IsNamedEscapeSequence ? 1 : 0) << (Features.CPlusPlus ? 1 : 0);
 
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 7e4ba98..62e51e1 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -434,7 +434,7 @@ void Preprocessor::SuggestTypoedDirective(const Token &Tok,
   std::vector<StringRef> Candidates = {
       "if", "ifdef", "ifndef", "elif", "else", "endif"
   };
-  if (LangOpts.C2x || LangOpts.CPlusPlus2b)
+  if (LangOpts.C2x || LangOpts.CPlusPlus23)
     Candidates.insert(Candidates.end(), {"elifdef", "elifndef"});
 
   if (std::optional<StringRef> Sugg = findSimilarStr(Directive, Candidates)) {
@@ -745,12 +745,12 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
         if (!CondInfo.WasSkipping)
           SkippingRangeState.endLexPass(Hashptr);
 
-        // Warn if using `#elifdef` & `#elifndef` in not C2x & C++2b mode even
+        // Warn if using `#elifdef` & `#elifndef` in not C2x & C++23 mode even
         // if this branch is in a skipping block.
         unsigned DiagID;
         if (LangOpts.CPlusPlus)
-          DiagID = LangOpts.CPlusPlus2b ? diag::warn_cxx2b_compat_pp_directive
-                                        : diag::ext_cxx2b_pp_directive;
+          DiagID = LangOpts.CPlusPlus23 ? diag::warn_cxx23_compat_pp_directive
+                                        : diag::ext_cxx23_pp_directive;
         else
           DiagID = LangOpts.C2x ? diag::warn_c2x_compat_pp_directive
                                 : diag::ext_c2x_pp_directive;
@@ -1256,10 +1256,10 @@ void Preprocessor::HandleDirective(Token &Result) {
 
     case tok::pp_warning:
       if (LangOpts.CPlusPlus)
-        Diag(Result, LangOpts.CPlusPlus2b
-                         ? diag::warn_cxx2b_compat_warning_directive
+        Diag(Result, LangOpts.CPlusPlus23
+                         ? diag::warn_cxx23_compat_warning_directive
                          : diag::ext_pp_warning_directive)
-            << /*C++2b*/ 1;
+            << /*C++23*/ 1;
       else
         Diag(Result, LangOpts.C2x ? diag::warn_c2x_compat_warning_directive
                                   : diag::ext_pp_warning_directive)
@@ -3423,14 +3423,14 @@ void Preprocessor::HandleElifFamilyDirective(Token &ElifToken,
                                                  : PED_Elifndef;
   ++NumElse;
 
-  // Warn if using `#elifdef` & `#elifndef` in not C2x & C++2b mode.
+  // Warn if using `#elifdef` & `#elifndef` in not C2x & C++23 mode.
   switch (DirKind) {
   case PED_Elifdef:
   case PED_Elifndef:
     unsigned DiagID;
     if (LangOpts.CPlusPlus)
-      DiagID = LangOpts.CPlusPlus2b ? diag::warn_cxx2b_compat_pp_directive
-                                    : diag::ext_cxx2b_pp_directive;
+      DiagID = LangOpts.CPlusPlus23 ? diag::warn_cxx23_compat_pp_directive
+                                    : diag::ext_cxx23_pp_directive;
     else
       DiagID = LangOpts.C2x ? diag::warn_c2x_compat_pp_directive
                             : diag::ext_c2x_pp_directive;
diff --git a/clang/lib/Lex/PPExpressions.cpp b/clang/lib/Lex/PPExpressions.cpp
index aa411cf..6c93514 100644
--- a/clang/lib/Lex/PPExpressions.cpp
+++ b/clang/lib/Lex/PPExpressions.cpp
@@ -323,13 +323,13 @@ static bool EvaluateValue(PPValue &Result, Token &PeekTok, DefinedTracker &DT,
         PP.Diag(PeekTok, diag::ext_c99_longlong);
     }
 
-    // 'z/uz' literals are a C++2b feature.
+    // 'z/uz' literals are a C++23 feature.
     if (Literal.isSizeT)
       PP.Diag(PeekTok, PP.getLangOpts().CPlusPlus
-                           ? PP.getLangOpts().CPlusPlus2b
+                           ? PP.getLangOpts().CPlusPlus23
                                  ? diag::warn_cxx20_compat_size_t_suffix
-                                 : diag::ext_cxx2b_size_t_suffix
-                           : diag::err_cxx2b_size_t_suffix);
+                                 : diag::ext_cxx23_size_t_suffix
+                           : diag::err_cxx23_size_t_suffix);
 
     // 'wb/uwb' literals are a C2x feature. We explicitly do not support the
     // suffix in C++ as an extension because a library-based UDL that resolves
diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index 4aecd48..717c014 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -1076,7 +1076,7 @@ SourceLocation Parser::ParseDecltypeSpecifier(DeclSpec &DS) {
     // Check for C++1y 'decltype(auto)'.
     if (Tok.is(tok::kw_auto) && NextToken().is(tok::r_paren)) {
       // the typename-specifier in a function-style cast expression may
-      // be 'auto' since C++2b.
+      // be 'auto' since C++23.
       Diag(Tok.getLocation(),
            getLangOpts().CPlusPlus14
                ? diag::warn_cxx11_compat_decltype_auto_type_specifier
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 14f48c7..b99baf4 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1871,7 +1871,7 @@ ExprResult Parser::ParseCastExpression(CastParseKind ParseKind,
 ///         primary-expression
 ///         postfix-expression '[' expression ']'
 ///         postfix-expression '[' braced-init-list ']'
-///         postfix-expression '[' expression-list [opt] ']'  [C++2b 12.4.5]
+///         postfix-expression '[' expression-list [opt] ']'  [C++23 12.4.5]
 ///         postfix-expression '(' argument-expression-list[opt] ')'
 ///         postfix-expression '.' identifier
 ///         postfix-expression '->' identifier
@@ -1946,10 +1946,10 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
 
       // We try to parse a list of indexes in all language mode first
       // and, in we find 0 or one index, we try to parse an OpenMP array
-      // section. This allow us to support C++2b multi dimensional subscript and
+      // section. This allow us to support C++23 multi dimensional subscript and
       // OpenMp sections in the same language mode.
       if (!getLangOpts().OpenMP || Tok.isNot(tok::colon)) {
-        if (!getLangOpts().CPlusPlus2b) {
+        if (!getLangOpts().CPlusPlus23) {
           ExprResult Idx;
           if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
             Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 54f5408..8f56316 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -725,7 +725,7 @@ ExprResult Parser::ParseCXXIdExpression(bool isAddressOfOperand) {
 ///         '&' identifier initializer
 ///
 ///       lambda-declarator:
-///         lambda-specifiers     [C++2b]
+///         lambda-specifiers     [C++23]
 ///         '(' parameter-declaration-clause ')' lambda-specifiers
 ///             requires-clause[opt]
 ///
@@ -1205,7 +1205,7 @@ static void tryConsumeLambdaSpecifierToken(Parser &P,
 static void addStaticToLambdaDeclSpecifier(Parser &P, SourceLocation StaticLoc,
                                            DeclSpec &DS) {
   if (StaticLoc.isValid()) {
-    P.Diag(StaticLoc, !P.getLangOpts().CPlusPlus2b
+    P.Diag(StaticLoc, !P.getLangOpts().CPlusPlus23
                           ? diag::err_static_lambda
                           : diag::warn_cxx20_compat_static_lambda);
     const char *PrevSpec = nullptr;
@@ -1362,7 +1362,7 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
   // or operator template declaration. We accept this as a conforming extension
   // in all language modes that support lambdas.
   if (isCXX11AttributeSpecifier()) {
-    Diag(Tok, getLangOpts().CPlusPlus2b
+    Diag(Tok, getLangOpts().CPlusPlus23
                   ? diag::warn_cxx20_compat_decl_attrs_on_lambda
                   : diag::ext_decl_attrs_on_lambda);
     MaybeParseCXX11Attributes(D);
@@ -1501,7 +1501,7 @@ ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
                   tok::kw_requires, tok::kw_noexcept) ||
       (Tok.is(tok::l_square) && NextToken().is(tok::l_square));
 
-  if (HasSpecifiers && !HasParentheses && !getLangOpts().CPlusPlus2b) {
+  if (HasSpecifiers && !HasParentheses && !getLangOpts().CPlusPlus23) {
     // It's common to forget that one needs '()' before 'mutable', an
     // attribute specifier, the result type, or the requires clause. Deal with
     // this.
@@ -1996,7 +1996,7 @@ Parser::ParseAliasDeclarationInInitStatement(DeclaratorContext Context,
   if (!DG)
     return DG;
 
-  Diag(DeclStart, !getLangOpts().CPlusPlus2b
+  Diag(DeclStart, !getLangOpts().CPlusPlus23
                       ? diag::ext_alias_in_init_statement
                       : diag::warn_cxx20_alias_in_init_statement)
       << SourceRange(DeclStart, DeclEnd);
diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 5a68e74..b423c5c 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -1053,7 +1053,7 @@ void Parser::ParseCompoundStatementLeadingPragmas() {
 
 void Parser::DiagnoseLabelAtEndOfCompoundStatement() {
   if (getLangOpts().CPlusPlus) {
-    Diag(Tok, getLangOpts().CPlusPlus2b
+    Diag(Tok, getLangOpts().CPlusPlus23
                   ? diag::warn_cxx20_compat_label_end_of_compound_statement
                   : diag::ext_cxx_label_end_of_compound_statement);
   } else {
@@ -1457,7 +1457,7 @@ StmtResult Parser::ParseIfStatement(SourceLocation *TrailingElseLoc) {
     }
 
     if (Tok.is(tok::kw_consteval)) {
-      Diag(Tok, getLangOpts().CPlusPlus2b ? diag::warn_cxx20_compat_consteval_if
+      Diag(Tok, getLangOpts().CPlusPlus23 ? diag::warn_cxx20_compat_consteval_if
                                           : diag::ext_consteval_if);
       IsConsteval = true;
       ConstevalLoc = ConsumeToken();
@@ -1929,7 +1929,7 @@ bool Parser::isForRangeIdentifier() {
 /// [C++] for-init-statement:
 /// [C++]   expression-statement
 /// [C++]   simple-declaration
-/// [C++2b] alias-declaration
+/// [C++23] alias-declaration
 ///
 /// [C++0x] for-range-declaration:
 /// [C++0x]   attribute-specifier-seq[opt] type-specifier-seq declarator
diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 2df9b19..07ece40 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -2169,7 +2169,7 @@ static void checkEscapingByref(VarDecl *VD, Sema &S) {
       new (S.Context) DeclRefExpr(S.Context, VD, false, T, VK_LValue, Loc);
   ExprResult Result;
   auto IE = InitializedEntity::InitializeBlock(Loc, T);
-  if (S.getLangOpts().CPlusPlus2b) {
+  if (S.getLangOpts().CPlusPlus23) {
     auto *E = ImplicitCastExpr::Create(S.Context, T, CK_NoOp, VarRef, nullptr,
                                        VK_XValue, FPOptionsOverride());
     Result = S.PerformCopyInitialization(IE, SourceLocation(), E);
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index eb31081..a746d8c 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -762,7 +762,7 @@ Sema::ActOnDecompositionDeclarator(Scope *S, Declarator &D,
   // C++20 [dcl.dcl]/8:
   //   If decl-specifier-seq contains any decl-specifier other than static,
   //   thread_local, auto, or cv-qualifiers, the program is ill-formed.
-  // C++2b [dcl.pre]/6:
+  // C++23 [dcl.pre]/6:
   //   Each decl-specifier in the decl-specifier-seq shall be static,
   //   thread_local, auto (9.2.9.6 [dcl.spec.auto]), or a cv-qualifier.
   auto &DS = D.getDeclSpec();
@@ -1928,16 +1928,16 @@ static bool CheckConstexprDeclStmt(Sema &SemaRef, const FunctionDecl *Dcl,
         if (VD->isStaticLocal()) {
           if (Kind == Sema::CheckConstexprKind::Diagnose) {
             SemaRef.Diag(VD->getLocation(),
-                         SemaRef.getLangOpts().CPlusPlus2b
+                         SemaRef.getLangOpts().CPlusPlus23
                              ? diag::warn_cxx20_compat_constexpr_var
                              : diag::ext_constexpr_static_var)
                 << isa<CXXConstructorDecl>(Dcl)
                 << (VD->getTLSKind() == VarDecl::TLS_Dynamic);
-          } else if (!SemaRef.getLangOpts().CPlusPlus2b) {
+          } else if (!SemaRef.getLangOpts().CPlusPlus23) {
             return false;
           }
         }
-        if (SemaRef.LangOpts.CPlusPlus2b) {
+        if (SemaRef.LangOpts.CPlusPlus23) {
           CheckLiteralType(SemaRef, Kind, VD->getLocation(), VD->getType(),
                            diag::warn_cxx20_compat_constexpr_var,
                            isa<CXXConstructorDecl>(Dcl),
@@ -2276,15 +2276,15 @@ static bool CheckConstexprFunctionBody(Sema &SemaRef, const FunctionDecl *Dcl,
   if (Kind == Sema::CheckConstexprKind::CheckValid) {
     // If this is only valid as an extension, report that we don't satisfy the
     // constraints of the current language.
-    if ((Cxx2bLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus2b) ||
+    if ((Cxx2bLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus23) ||
         (Cxx2aLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus20) ||
         (Cxx1yLoc.isValid() && !SemaRef.getLangOpts().CPlusPlus17))
       return false;
   } else if (Cxx2bLoc.isValid()) {
     SemaRef.Diag(Cxx2bLoc,
-                 SemaRef.getLangOpts().CPlusPlus2b
+                 SemaRef.getLangOpts().CPlusPlus23
                      ? diag::warn_cxx20_compat_constexpr_body_invalid_stmt
-                     : diag::ext_constexpr_body_invalid_stmt_cxx2b)
+                     : diag::ext_constexpr_body_invalid_stmt_cxx23)
         << isa<CXXConstructorDecl>(Dcl);
   } else if (Cxx2aLoc.isValid()) {
     SemaRef.Diag(Cxx2aLoc,
@@ -15976,7 +15976,7 @@ bool Sema::CheckOverloadedOperatorDeclaration(FunctionDecl *FnDecl) {
     if (MethodDecl->isStatic()) {
       if (Op == OO_Call || Op == OO_Subscript)
         Diag(FnDecl->getLocation(),
-             (LangOpts.CPlusPlus2b
+             (LangOpts.CPlusPlus23
                   ? diag::warn_cxx20_compat_operator_overload_static
                   : diag::ext_operator_overload_static))
             << FnDecl;
@@ -16017,7 +16017,7 @@ bool Sema::CheckOverloadedOperatorDeclaration(FunctionDecl *FnDecl) {
     }
     if (FirstDefaultedParam) {
       if (Op == OO_Subscript) {
-        Diag(FnDecl->getLocation(), LangOpts.CPlusPlus2b
+        Diag(FnDecl->getLocation(), LangOpts.CPlusPlus23
                                         ? diag::ext_subscript_overload
                                         : diag::error_subscript_overload)
             << FnDecl->getDeclName() << 1
@@ -16068,7 +16068,7 @@ bool Sema::CheckOverloadedOperatorDeclaration(FunctionDecl *FnDecl) {
   }
 
   if (Op == OO_Subscript && NumParams != 2) {
-    Diag(FnDecl->getLocation(), LangOpts.CPlusPlus2b
+    Diag(FnDecl->getLocation(), LangOpts.CPlusPlus23
                                     ? diag::ext_subscript_overload
                                     : diag::error_subscript_overload)
         << FnDecl->getDeclName() << (NumParams == 1 ? 0 : 2);
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index ce5f5fa..622b364 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -3957,13 +3957,13 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
   } else {
     QualType Ty;
 
-    // 'z/uz' literals are a C++2b feature.
+    // 'z/uz' literals are a C++23 feature.
     if (Literal.isSizeT)
       Diag(Tok.getLocation(), getLangOpts().CPlusPlus
-                                  ? getLangOpts().CPlusPlus2b
+                                  ? getLangOpts().CPlusPlus23
                                         ? diag::warn_cxx20_compat_size_t_suffix
-                                        : diag::ext_cxx2b_size_t_suffix
-                                  : diag::err_cxx2b_size_t_suffix);
+                                        : diag::ext_cxx23_size_t_suffix
+                                  : diag::err_cxx23_size_t_suffix);
 
     // 'wb/uwb' literals are a C2x feature. We support _BitInt as a type in C++,
     // but we do not currently support the suffix in C++ mode because it's not
@@ -4043,7 +4043,7 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
         Ty = Context.getBitIntType(Literal.isUnsigned, Width);
       }
 
-      // Check C++2b size_t literals.
+      // Check C++23 size_t literals.
       if (Literal.isSizeT) {
         assert(!Literal.MicrosoftInteger &&
                "size_t literals can't be Microsoft literals");
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index c440a4d..2bf5e6a 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -1467,10 +1467,10 @@ Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
           : InitializationKind::CreateValue(TyBeginLoc, LParenOrBraceLoc,
                                             RParenOrBraceLoc);
 
-  // C++1z [expr.type.conv]p1:
+  // C++17 [expr.type.conv]p1:
   //   If the type is a placeholder for a deduced class type, [...perform class
   //   template argument deduction...]
-  // C++2b:
+  // C++23:
   //   Otherwise, if the type contains a placeholder type, it is replaced by the
   //   type determined by placeholder type deduction.
   DeducedType *Deduced = Ty->getContainedDeducedType();
@@ -1497,7 +1497,7 @@ Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
                             diag::err_auto_expr_init_multiple_expressions)
                        << Ty << FullRange);
     }
-    if (getLangOpts().CPlusPlus2b) {
+    if (getLangOpts().CPlusPlus23) {
       if (Ty->getAs<AutoType>())
         Diag(TyBeginLoc, diag::warn_cxx20_compat_auto_expr) << FullRange;
     }
@@ -4022,7 +4022,7 @@ ExprResult Sema::CheckCXXBooleanCondition(Expr *CondExpr, bool IsConstexpr) {
   // The value of a condition that is an expression is the value of the
   // expression, implicitly converted to bool.
   //
-  // C++2b 8.5.2p2
+  // C++23 8.5.2p2
   // If the if statement is of the form if constexpr, the value of the condition
   // is contextually converted to bool and the converted expression shall be
   // a constant expression.
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index 84a1fd8..53e453b 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -255,7 +255,7 @@ Sema::ActOnModuleDecl(SourceLocation StartLoc, SourceLocation ModuleLoc,
     }
   }
 
-  // C++2b [module.unit]p1: ... The identifiers module and import shall not
+  // C++23 [module.unit]p1: ... The identifiers module and import shall not
   // appear as identifiers in a module-name or module-partition. All
   // module-names either beginning with an identifier consisting of std
   // followed by zero or more digits or containing a reserved identifier
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index 2f26c8f..135bf80 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -9929,7 +9929,7 @@ bool clang::isBetterOverloadCandidate(
     }
   }
 
-  // C++ [over.match.best]p1: (Changed in C++2b)
+  // C++ [over.match.best]p1: (Changed in C++23)
   //
   //   -- if F is a static member function, ICS1(F) is defined such
   //      that ICS1(F) is neither better nor worse than ICS1(G) for
@@ -15099,7 +15099,7 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
   bool IsError = false;
 
   // Initialize the implicit object parameter if needed.
-  // Since C++2b, this could also be a call to a static call operator
+  // Since C++23, this could also be a call to a static call operator
   // which we emit as a regular CallExpr.
   if (Method->isInstance()) {
     ExprResult ObjRes = PerformObjectArgumentInitialization(
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 1af5f73..7daebbd 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -3364,7 +3364,7 @@ Sema::ActOnBreakStmt(SourceLocation BreakLoc, Scope *CurScope) {
 /// might be modified by the implementation.
 ///
 /// \param Mode Overrides detection of current language mode
-/// and uses the rules for C++2b.
+/// and uses the rules for C++23.
 ///
 /// \returns An aggregate which contains the Candidate and isMoveEligible
 /// and isCopyElidable methods. If Candidate is non-null, it means
@@ -3385,7 +3385,7 @@ Sema::NamedReturnInfo Sema::getNamedReturnInfo(Expr *&E,
   if (Res.Candidate && !E->isXValue() &&
       (Mode == SimplerImplicitMoveMode::ForceOn ||
        (Mode != SimplerImplicitMoveMode::ForceOff &&
-        getLangOpts().CPlusPlus2b))) {
+        getLangOpts().CPlusPlus23))) {
     E = ImplicitCastExpr::Create(Context, VD->getType().getNonReferenceType(),
                                  CK_NoOp, E, nullptr, VK_XValue,
                                  FPOptionsOverride());
@@ -3529,7 +3529,7 @@ ExprResult Sema::PerformMoveOrCopyInitialization(
     const InitializedEntity &Entity, const NamedReturnInfo &NRInfo, Expr *Value,
     bool SupressSimplerImplicitMoves) {
   if (getLangOpts().CPlusPlus &&
-      (!getLangOpts().CPlusPlus2b || SupressSimplerImplicitMoves) &&
+      (!getLangOpts().CPlusPlus23 || SupressSimplerImplicitMoves) &&
       NRInfo.isMoveEligible()) {
     ImplicitCastExpr AsRvalue(ImplicitCastExpr::OnStack, Value->getType(),
                               CK_NoOp, Value, VK_XValue, FPOptionsOverride());
@@ -3902,7 +3902,7 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp,
 
 static bool CheckSimplerImplicitMovesMSVCWorkaround(const Sema &S,
                                                     const Expr *E) {
-  if (!E || !S.getLangOpts().CPlusPlus2b || !S.getLangOpts().MSVCCompat)
+  if (!E || !S.getLangOpts().CPlusPlus23 || !S.getLangOpts().MSVCCompat)
     return false;
   const Decl *D = E->getReferencedDeclOfCallee();
   if (!D || !S.SourceMgr.isInSystemHeader(D->getLocation()))
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 19a41b0..da105e3 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -3645,7 +3645,7 @@ static QualType GetDeclSpecTypeForDeclarator(TypeProcessingState &state,
     case DeclaratorContext::FunctionalCast:
       if (isa<DeducedTemplateSpecializationType>(Deduced))
         break;
-      if (SemaRef.getLangOpts().CPlusPlus2b && IsCXXAutoType &&
+      if (SemaRef.getLangOpts().CPlusPlus23 && IsCXXAutoType &&
           !Auto->isDecltypeAuto())
         break; // auto(x)
       [[fallthrough]];