Use webassembly exception handling

[hoodmane]

It's a bit hard to make the rust compiler play along, see the upstream PR for information about the rust difficulties pyodide/pyodide-build#81

Based on / supersedes #3817

• Add a CHANGELOG entry

Build failures

• python-flint
• ppl
• gdal

Import failures

These use setjmp/longjmp and have errors because the symbols for setjmp/longjmp are missing.

• opencv
• rasterio
• optlang
• fiona
• swiglpk
• pyiceberg
• pygame-ce

[hoodmane]

The only core test failure is test_cpp_exceptions_and_syncify which we'll need to deal with
emscripten-core/emscripten#23395
in order to fix. This isn't exactly a regression either, I think the bug exists on the main branch but this change makes our test hit it.

[hoodmane]

Clarabel has to be disabled until they resolve a problem with the newest beta rust.
oxfordcontrol/Clarabel.rs#154

[hoodmane]

@agriyakhetarpal @ryanking13 I think all tests are passing now, would appreciate if you could review this and pyodide/pyodide-build#81.

[ryanking13]

Thanks for working on this Hood. I'll review it soon, probably before this weekend.

[agriyakhetarpal]

Thanks for the ping here, @hoodmane. I can't say I understand all of the details, but it looks good to me – I'll be echoing some of @ryanking13's previous comments.

[agriyakhetarpal]

I remember that pybind11's tests for Pyodide/WASM downstream were also passing -fexceptions. Should they also switch to -fwasm-exceptions once this PR makes it to a release?

[hoodmane]

Yes everyone downstream needs to pass -fwasm-exceptions or they will get load time errors.

[hoodmane]

But it'll be a bit annoying if they want to build for both Pyodide 0.27 and Pyodide 0.28 since they need different flags.

[agriyakhetarpal]

Yes, that would be a breaking change for cibuildwheel. Could we document this better in the CHANGELOG? Maybe we can intercept this in pywasmcross, raising a warning and switching it out internally if set? I haven't contributed to that side of our codebase before, so if yes, I would be happy to try that out.

[hoodmane]

I should clarify further about sjlj in the changelog.

[ryanking13]

Thanks @hoodmane! Codewise looks good to me. Could you please address the comments that I had left in the pyodide-build side changes? pyodide/pyodide-build#81

Specifically, I think a comment regarding sjlj flag needs to be addressed, as the flag has been changed in the latest version of emscripten.

[agriyakhetarpal]

Thanks, @hoodmane!

[hoodmane]

Okay let's merge it =D