[clang] [clang-tools-extra] [clang][Serialization] Serialize DiagStateOnPushStack to fix pragma d… (PR #190420)

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brandonxin wrote:

Thanks everyone for the reviews and discussion! It sounds like there's consensus to land this patch.

@HighCommander4  @ArcsinX  @ChuanqiXu9  would any of you be able to approve this PR so we can move forward?

Regarding the `#pragma pack(push, 1)` issue @ArcsinX raised — I'm happy to investigate that separately and submit a follow-up PR if needed.

https://github.com/llvm/llvm-project/pull/190420