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

[via cfe-commits]

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@@ -8361,6 +8361,17 @@ class ExprEvaluatorBase
         return false;
     }
 
+    // If an assertion fails during constant evaluation, give a specific note explaining that
+    if (FD->getName() == "__assert_fail") {
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cor3ntin wrote:

Either way, we need a test where the message is a `const wchar_t*`

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