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

[Amy Huang via cfe-commits]

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@@ -3055,7 +3195,7 @@ void MicrosoftRecordLayoutBuilder::injectVBPtr(const CXXRecordDecl *RD) {
     // It is possible that there were no fields or bases located after vbptr,
     // so the size was not adjusted before.
     if (Size < FieldStart)
-      Size = FieldStart;
+      DataSize = Size = FieldStart;
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amykhuang wrote:

I realized I can reduce the places that DataSize is set, and I think it's more readable this way? 

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