[clang] [Clang] Implement P2280R4 Using unknown pointers and references in constant expressions (PR #95474)

[via cfe-commits]

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@@ -8595,7 +8643,10 @@ bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
 
 
 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
-
+  // P2280R4 if we are in C++23 track if we have an unknown reference or
+  // pointer.
+  bool AllowConstexprUnknown =
+      Info.getLangOpts().CPlusPlus23 && VD->getType()->isReferenceType();
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cor3ntin wrote:

Same comment as above for the DR/comment

https://github.com/llvm/llvm-project/pull/95474