[clang] Reland "[Modules] Record whether VarDecl initializers contain side effects" (PR #145447)

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bgra8 wrote:

> Do you have a reproducer you can share?

Working to get a smaller repro. But this only reproduces for builds with modules enabled so it will take some time.

>  Does the type that's being casted to RecordType have RecordType as the canonical type, or is it completely off? 

The compiler seems to choke on serializing a const member initialized with a value of the same type as the member (but the type is the result of multiple macro expansions and I didn't have yet the time to investigate thoroughly)

> You don't happen to be using the new constant interpreter?

Not sure what you mean by this. We're using the unmodified compiler and testing its correctness on google internal code.


https://github.com/llvm/llvm-project/pull/145447