[clang] [clang] Implement CWG2815 (PR #132778)

[via cfe-commits]

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@@ -5229,10 +5229,23 @@ TryReferenceInit(Sema &S, Expr *Init, QualType DeclType,
       S.CompareReferenceRelationship(DeclLoc, T1, T2, &RefConv);
 
   auto SetAsReferenceBinding = [&](bool BindsDirectly) {
+    // C++2c [over.ics.ref] p1:
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offsetof wrote:

Right - the wording appears first in C++26 but the relevant changes are DRs.

https://github.com/llvm/llvm-project/pull/132778