[clang] Better diagnostics when assertion fails in `consteval` (PR #130458)

[via cfe-commits]

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@@ -5975,9 +5975,22 @@ static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
                                         Definition->hasAttr<MSConstexprAttr>())))
     return true;
 
-  if (Info.getLangOpts().CPlusPlus11) {
-    const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
+  const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
+  // Special note for the assert() macro, as the normal error message falsely
+  // implies we cannot use an assertion during constant evaluation.
+  if (CallLoc.isMacroID() && DiagDecl->getIdentifier()) {
+    // FIXME: Instead of checking for an implementation-defined function,
+    // check and evaluate the assert() macro.
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cor3ntin wrote:

Oh, right, we would need access to Sema, which we currently don't. Good answer! (@Endilll !)
Given that, I am satisfied with the change as is, thanks

https://github.com/llvm/llvm-project/pull/130458