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

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> When you say you want a second opinion on CodeGen changes, do you mean RecordLayoutBuilder.cpp? I don't see any non-whitespace changes to clang/lib/CodeGen/ .

Sorry for the confusion, yes, I was mostly worried about RecordLayoutBuilder.cpp and whether you spotted any concerns with the changes.

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