[clang] Implement [[msvc::no_unique_address]] (PR #65675)

[Amy Huang via cfe-commits]

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@@ -4505,6 +4505,14 @@ bool FieldDecl::isZeroSize(const ASTContext &Ctx) const {
   if (!CXXRD->isEmpty())
     return false;
 
+  // MS ABI: nonzero if class type with class type fields
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amykhuang wrote:

As far as I can tell the cases above still apply to MSVC so I think on 4489 it's correct to account for both spellings. Not sure what you mean about the comment? The existing comment above the `isEmpty` line describes what that checks for

https://github.com/llvm/llvm-project/pull/65675