`macos-latest` builds are failing with `sigaltstack failed: Invalid argument`

[sbc100]

I suppose the github CI runners were updated and now we see these failures.

[sbc100]

@shravanrn @keithw do either you have have access to macOS machine such that you could debug this?

[shravanrn]

So this is an issue I have seen before, for example when attempting to migrate to a consistent use of thread_locals in the mac platform (See #2569).

From what I can tell, the failures I saw was an instance of undefined behavior in the exception implementation in wasm2c, leading to bad data being sent to sigaltstack (during the sigaltstack uninstall code that runs during app shutdown)

I deferred investigating a fix at the time as Firefox neither used the wasm exception or sigaltstack implementation, and also didn't end up pushing #2569. I can try to get to this at some point, but unfortunately, September is super busy for me, so I'm not likely going to be able to get to this very soon.

@keithw any chance you have some cycles?