[clang] [C2y] Implement WG14 N3369 and N3469 (_Countof) (PR #133125)

[via cfe-commits]

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@@ -14926,6 +14926,42 @@ bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
 
     return false;
   }
+  case UETT_CountOf: {
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cor3ntin wrote:

Did you consider the new interpreter? @tbaederr 

https://github.com/llvm/llvm-project/pull/133125