[clang] [C23] Implement N3018: The constexpr specifier for object definitions (PR #73099)

[Mariya Podchishchaeva via cfe-commits]

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@@ -5140,6 +5140,8 @@ Decl *Sema::ParsedFreeStandingDeclSpec(Scope *S, AccessSpecifier AS,
       Diag(DS.getConstexprSpecLoc(), diag::err_constexpr_tag)
           << GetDiagnosticTypeSpecifierID(DS)
           << static_cast<int>(DS.getConstexprSpecifier());
+    else if (getLangOpts().C23)
+      Diag(DS.getConstexprSpecLoc(), diag::err_c23_constexpr_not_variable);
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Fznamznon wrote:

Ignoring per https://github.com/llvm/llvm-project/pull/73099#discussion_r1491320091 .

https://github.com/llvm/llvm-project/pull/73099