[clang] [Clang][C++23] Implement P2448R2: Relaxing some constexpr restrictions (PR #77753)

[via cfe-commits]

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@@ -1754,11 +1761,17 @@ static bool CheckConstexprParameterTypes(Sema &SemaRef,
     const ParmVarDecl *PD = FD->getParamDecl(ArgIndex);
     assert(PD && "null in a parameter list");
     SourceLocation ParamLoc = PD->getLocation();
-    if (CheckLiteralType(SemaRef, Kind, ParamLoc, *i,
-                         diag::err_constexpr_non_literal_param, ArgIndex + 1,
-                         PD->getSourceRange(), isa<CXXConstructorDecl>(FD),
-                         FD->isConsteval()))
+    if (CheckLiteralType(
+            SemaRef, Kind, ParamLoc, *i,
+            SemaRef.getLangOpts().CPlusPlus23
+                ? diag::warn_cxx23_compat_constexpr_non_literal_param
+                : diag::ext_constexpr_non_literal_param,
+            ArgIndex + 1, PD->getSourceRange(), isa<CXXConstructorDecl>(FD),
+            FD->isConsteval())) {
+      if (SemaRef.getLangOpts().CPlusPlus23)
+        return true;
       return false;
+    }
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cor3ntin wrote:

ditto

https://github.com/llvm/llvm-project/pull/77753