Conan cross-compiling

[avetiso]

Apologies this isn't in the conan repo, they don't have a discussion section and I have received no response in their slack channel for this question :(

I am trying to cross-compile using meson, but executed via the conan helper functions for meson.

We have an internal tool that we use to generate conan profiles based on a set of arguments, so for example bx mx-conan create realease ios should call conan with the correct profile and pass it the arch, build type, compiler, OS version, etc.

Using that information in the conanfile.py, I am trying to detect the target OS and provide the corresponding cross file to meson.

    def build(self):
        build_args = []

        if self.settings.os == "iOS":
            build_args.append("--cross-file cross/ios.txt")

        meson = Meson(self, build_type=self.settings.build_type)
        meson.configure(build_folder="build")
        meson.build(args=build_args) # pass the cross file here

Meson does not seem to do anything with this argument when I pass it to build(), but it doesn't error out, either. I have verified that I am hitting the correct paths I expect to in this code and that the arg is indeed in that list getting passed to build().

If I try to pass it to configure() it does fail, saying that it is an unsupported argument.

The cross file works as expected when I do things manually from the command line.

Is this the idiomatic way to pass cross-compile files to meson when using conan?

[eli-schwartz]

I don't know how Conan works, but you will need to make sure that the argument is being passed to whichever Conan function is running the meson setup command under the hood.

At a guess, the "build" function seems like it would be running ninja after the build had been set up. What's the exact text of the error message when you pass it to configure instead?

[avetiso]

The following is the error if I try to pass it to configure(). There are single quotes in the output around the cross-file arg, not sure how I'm supposed to rid myself of those since I create my args as a list of strings and the only entry in that list is the string '--cross-file cross/ios.txt'. Perhaps there some simple Python knowledge I don't know lol.

You are right about build() actually deferring to either a call to ninja or 'meson compile' https://github.com/conan-io/conan/blob/develop/conans/client/build/meson.py

Conan does provide a method to simply run meson commands, but when I try to use it to run setup there is a -C that's always inserted into the call to meson that ends up breaking it. Seems like a conan issue, not sure why they didn't expose an easy way to use cross files. Doesn't seem to be any serious examples of conan/meson being used together out there for me to study, either.

usage: meson [-h] {setup,configure,dist,install,introspect,init,test,wrap,subprojects,help,rewrite,compile,devenv} ...
meson: error: unrecognized arguments: --cross-file cross/ios.txt
base64/1.0.0-5@mx/stable: 
base64/1.0.0-5@mx/stable: ERROR: Package 'b55b855369793ce36245589d74115f074874150a' build failed
base64/1.0.0-5@mx/stable: WARN: Build folder /Users/dario.avetisov/.conan/data/base64/1.0.0-5/mx/stable/build/b55b855369793ce36245589d74115f074874150a
ERROR: base64/1.0.0-5@mx/stable: Error in build() method, line 35
        meson.configure(args=args, build_folder="build")
        ConanException: Error 2 while executing meson "/Users/dario.avetisov/.conan/data/base64/1.0.0-5/mx/stable/build/b55b855369793ce36245589d74115f074874150a" "/Users/dario.avetisov/.conan/data/base64/1.0.0-5/mx/stable/build/b55b855369793ce36245589d74115f074874150a/build" --backend=ninja -Dprefix="/Users/dario.avetisov/.conan/data/base64/1.0.0-5/mx/stable/package/b55b855369793ce36245589d74115f074874150a" -Dlibdir="lib" -Dbindir="bin" -Dsbindir="bin" -Dlibexecdir="bin" -Dincludedir="include" -Ddefault_library="shared" '--cross-file cross/ios.txt' --buildtype=debug
conan create . mx/stable -u -pr ios-debug -s os.version=11.0 -s compiler.version=13.0
Error: Command returned pid 821 exit 1

[avetiso]

Running the command without the single quotes actually seems to work, so it seems I'm misusing python/conan actually

[eli-schwartz]

Alright, looking at that conan definition it seems that configure(args=...) accepts a list.

Looking back at your original attempt, the error you get seems to make sense, because you append a single string to the args, and then that entire string gets accepted as a single argument to meson. Can you try:

build_args.extend(["--cross-file", "cross/ios.txt"])

Then as mentioned above, use it with meson.configure() rather than meson.build()

[avetiso]

that worked! thank you so much, I figured it was the quote that were breaking it, but looks like the single quotes work just fine, it's just that it was within the same string

[avetiso]

do you take any sort of donations for your help with FOSS?