Boost: Broken detection when cross compiling to Windows hosts

[mia-0]

Python system: Linux
Version: 0.43.0

When cross compiling to Windows using a mingw-w64 toolchain, the Boost dependency detection is broken and can’t find the libraries.

Problem is probably right here:

meson/mesonbuild/dependencies/misc.py

Lines 230 to 233 in e51da1a

	def detect_lib_modules(self):
	if mesonlib.is_windows():
	return self.detect_lib_modules_win()
	return self.detect_lib_modules_nix()

Also, this needs more logging. Can’t even tell what it’s looking for.

[nirbheek]

@NickeZ, could you look into this and also add more debug logging with mlog.debug()?

[NickeZ]

I never tried cross compiling with boost. I probably won't set this up and try it..

[mia-0]

I never tried cross compiling with boost. I probably won't set this up and try it..

This should be quite easy with mxe. Basically, Meson’s Boost detection assumes that Windows == MSVC, and lifting that assumption would most likely fix this issue.

[bredelings]

On Debian a cross build involved installing g++-mingw-w64, wine and wine32. Building the boost dependency so that meson can try to find it might be more work.

Probably most of the occurrences of is_windows() and is_linux() need to be changed to for_windows( ) and for_darwin( ). Specifically,

• mesonlib.is_windows() -> mesonlib.for_windows(self.want_cross, self.env)
• mesonlib.is_osx() -> mesonlib.for_darwin(self.want_cross, self.env)

Maybe we should add methods self.for_windows() and self.for_darwin() to ExternalDependency or Dependency?

[lyakhov]

I can confirm the issue exists on Fedora 27 cross-compiling using mingw32 -- and using precompiled boost packages (mingw32-boost, mingw32-boost-static).

Hopefully, there is a workaround, as mentioned at https://unix.stackexchange.com/questions/408963/meson-doesnt-find-the-boost-libraries:

    cxx = meson.get_compiler('cpp')
    boost_dep = [
        cxx.find_library('boost_system'),
        cxx.find_library('ws2_32')
    ]

(that is particular case for boost asio using Windows sockets for TCP)

[bredelings]

See also #2990

[bredelings]

@lachs0r I think this is fixed now in current master. Can you try it out?

[mia-0]

Sorry about the late response. Seems to work now. Thanks!