[clang] [Clang] Support MSPropertyRefExpr as placement arg to new-expression (PR #75883)

[via cfe-commits]

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@@ -2286,6 +2286,9 @@ ExprResult Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
   bool PassAlignment = getLangOpts().AlignedAllocation &&
                        Alignment > NewAlignment;
 
+  if (CheckArgsForPlaceholders(PlacementArgs))
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Sirraide wrote:

Alright, just got done adding some tests. Just let me know if there are more things that we should consider testing. 

Also, regarding Objective-C++ properties: I tried following the examples in `clang/test/AST/ast-dump-expr-json.m`, but it didn’t seem to want to treat the subscripts as anything other than pointer arithmetic. It also doesn’t help that I’m not familiar w/ Objective-C/Objective-C++ at all. Could it be that Objective-C subscript properties are disabled in Objective-C++ mode?

https://github.com/llvm/llvm-project/pull/75883