[clang] [Clang] Diagnose forming references to nullptr (PR #143667)

[Shafik Yaghmour via cfe-commits]

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@@ -4426,7 +4431,7 @@ static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
 
     // Unless we're looking at a local variable or argument in a constexpr call,
     // the variable we're reading must be const.
-    if (!Frame) {
+    if (AK != clang::AK_ReferenceInitialization && !Frame) {
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shafik wrote:

Can you explain why you are pairing these checks? I am missing the logic, maybe a comment should be added?

https://github.com/llvm/llvm-project/pull/143667