[clang] [Clang] Improve diagnostics for 'placement new' with const storage argument (PR #144270)

[Oliver Hunt via cfe-commits]

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@@ -2753,10 +2753,18 @@ static bool resolveAllocationOverloadInterior(
     if (Diagnose) {
       // If this is an allocation of the form 'new (p) X' for some object
       // pointer p (or an expression that will decay to such a pointer),
-      // diagnose the missing inclusion of <new>.
+      // diagnose potential error.
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ojhunt wrote:

pedantic: "diagnose the reason for the error."

https://github.com/llvm/llvm-project/pull/144270