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

[Baranov Victor 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.
       if (!R.isClassLookup() && Args.size() == 2 &&
           (Args[1]->getType()->isObjectPointerType() ||
            Args[1]->getType()->isArrayType())) {
+        if (Args[1]->getType()->isPointerType()) {
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vbvictor wrote:

> should probably be earlier - this is inside an array of object check

We have `isObjectPointerType() || isArrayType()` in first `if`, so pointer are handled correctly, I added tests for that.

I used `Context.getBaseElementType()`, but still had to manually check for pointer because it only unwraps arrays. 

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