change DEFAULT_STACK_SIZE to be 32MB on s390x

[fneddy]

tests/ui/match/match-stack-overflow-72933-.rs crashes on s390x due to hitting stack_size limit(#161742).
changing the size to 32MB on s390x fixes the crash.

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[ChrisDenton]

I'd rather we increased it for all (or most) platforms. Though does it need to be 32MB? There's no real reason to keep going up in powers of two, although having some leeway is useful.

Maybe we could keep the 16MB for 32-bit targets since those are more sensitive to thread stack sizes.

[fneddy]

ok i tested it. funny enough 17mb lets it pass. I guess setting it to 17mb for everybody wont hurt?

however i want to emphasize that some passes in rust are recursive and therefore one can always create a valid rust program that will segfault the compiler. indifferent of the architecture.

[ChrisDenton]

Yeah, I don't really like tests that simply stress the recursion for no real reason. If someone has unusually extreme needs then that's what the environment variable is for (similarly, we have recursion_limit for some things). If however it is more representative of real world usage then we should absolute try to accommodate them by default.

[ChrisDenton]

LGTM, thanks! In the unlikely event this causes problems for anyone there's still plenty of time for this to be caught during nightly/beta.

@bors r+

[rust-bors]

📌 Commit d3a3f13 has been approved by ChrisDenton

It is now in the queue for this repository.