setjmp support

[calvin2021y]

current sdk ./share/wasi-sysroot/include/c++/v1/setjmp.h is not working.

please share the roadmap for this sdk to support setjmp, I want use it in https://github.com/protocolbuffers/upb

[sunfishcode]

The current plan is to wait for the exception-handling proposal to be standardized and implemented in wasm engines, and then to implement setjmp and longjmp using that feature. Exception-handling is currently in phase 3.

Another option would be to define a host API which performs stack unwinding. We've so far not pursued this approach, because that would be a lot of complex work for non-JS host API implementors, for what would ultimately be a temporary workaround. And, such an API would not be virtualizable, and would raise complex questions about non-C-language unwinding which the exception-handling proposal already has answers for.

[sunfishcode]

The original question is answered; please file new issues for any further questions!

[namse]

@sunfishcode According to WebAssembly/exception-handling#179, it seems that most browsers have completed the implementation. It's in Phase 3, but since the implementation has been completed, would it be okay to provide support for it?

[sunfishcode]

Yes, an implementation is now merged into wasi-libc in WebAssembly/wasi-libc#483.