-Werror=implicit-function-declaration, strictly necessary?

[AndrewAnnex]

I am pretty new to pyodide and cmake but I am attempting to use cibuildwheel with scikit-core-build to wrap a C library that uses very old (like c89) conventions and for complicated reasons isn't easily patchable. The library does not ship a cmakelists file, so I am authoring one at https://github.com/AndrewAnnex/cspice-cmake-spiceypy which I have control over.

With cibuildwheel, I am running into errors due to the inclusion of -Werror=implicit-function-declaration that is getting appended in pywasmcorss.py.

pyodide-build/pyodide_build/pywasmcross.py

Lines 589 to 595 in 3534e86

	new_args.extend(
	[
	"-Werror=implicit-function-declaration",
	"-Werror=mismatched-parameter-types",
	"-Werror=return-type",
	]
	)

My basic question, not being deeply familiar with pyodide, is if this is actually necessary to hardcode within pyodide-build? Could it be possible to make this adjustable via environment variables etc?

If it is absolutely necessary, I would appreciate advice for what else I can do. I am very new to cmake, but maybe there are some better ways to patch source files to make these adjustments.

[ryanking13]

Maybe we can remove those hardcoded flags and make it configurable. Meanwhile, I think you can try appending -Wno-error=implicit-function-declaration in CFLAGS. I think LLVM will choose the last option.

[hoodmane]

That's right. I don't think we need to make them configurable since people can turn them back off with build: cflags: or the CFLAGS environment variable.

[hoodmane]

Also, isn't C code that doesn't build with -Wno-error=implicit-function-declaration a bit broken?

[ryanking13]

Also, isn't C code that doesn't build with -Wno-error=implicit-function-declaration a bit broken?

I think so, but the author mentioned "a very old code using c89 standard", so maybe the code was written in that way.

[AndrewAnnex]

thanks all, yeah this code is fortan77, translated with some unknown f2c version, and so is a bit of a mess. I am extending my cmake to patch things and set flags differently for emscripten now, just having some confusion/issues around making it a side module, but think that is better handled in a new discussion/or elsewhere