meson 0.52.0 breaks cross compilation due to linker "guess"

[saurik]

With meson 0.52.0, there is a new function _guess_nix_linker in environment.py that attempts to guess the linker being used; it does this by passing -Wl,--version to the compiler, but as it doesn't pass the various compiler flags added in a --cross-file, it returns the default linker for the build system instead of the chosen linker for the host system (which might be the default for a --target or might be a specific override due to -B or -fuse-ld). This worked fine with 0.51.1.

In my case, I have the following --cross-file, which uses clang from the Android NDK and overrides --target, at which point it will use a GNU linker (sometimes gold); by default, however, this version of clang will happily compile for macOS, and so will run ld64 if no arguments are passed. (FWIW, I partly include this as maybe I'm using the arguments wrong, like maybe I need to be putting these --target arguments somewhere more fundamental than merely c_args?)

[host_machine]
system = 'linux'
cpu_family = 'aarch64'
cpu = 'aarch64'
endian = 'little'

[properties]
c_args = ['--sysroot=/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot', '-fno-addrsig', '-target', 'aarch64-unknown-linux-android21', '-gfull', '-Os', '-fdebug-prefix-map=./=', '-fdebug-prefix-map=/Users/saurik/orchid/app-android=.', '-fdata-sections', '-ffunction-sections', '-fvisibility=hidden', '-fPIC', '-I/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/include']
cpp_args = ['--sysroot=/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot', '-fno-addrsig', '-stdlib=libc++', '-target', 'aarch64-unknown-linux-android21', '-gfull', '-Os', '-fdebug-prefix-map=./=', '-fdebug-prefix-map=/Users/saurik/orchid/app-android=.', '-fdata-sections', '-ffunction-sections', '-fvisibility=hidden', '-fPIC', '-I/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/include']
objc_args = ['aarch64-unknown-linux-android21', '-gfull', '-Os', '-fdebug-prefix-map=./=', '-fdebug-prefix-map=/Users/saurik/orchid/app-android=.', '-fdata-sections', '-ffunction-sections', '-fvisibility=hidden', '-fPIC', '-I/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/include']
c_link_args = ['--sysroot=/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot', '-fno-addrsig', '-target', 'aarch64-unknown-linux-android21', '-L/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/lib']
cpp_link_args = ['--sysroot=/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot', '-fno-addrsig', '-stdlib=libc++', '-target', 'aarch64-unknown-linux-android21', '-L/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/lib']
objc_link_args = ['aarch64-unknown-linux-android21', '-L/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/lib']

[binaries]
c = '/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang'
cpp = '/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang++'
objc = '-target'
ar = '/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/aarch64-linux-android-ar'
strip = '/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/aarch64-linux-android-strip'
pkgconfig = '/Users/saurik/orchid/app-android/env/pkg-config'

Here is the output from meson, instrumenting the run process with RUNNING lines.

RUNNING ['cc', '-Wl,--version']
ld: unknown option: --version
clang: error: linker command failed with exit code 1 (use -v to see invocation)

C compiler for the build machine: ccache cc (clang 10.0.1 "Apple LLVM version 10.0.1 (clang-1001.0.46.3)")
C linker for the build machine: APPLE ld 450.3
RUNNING ['c++', '-Wl,--version']
ld: unknown option: --version
clang: error: linker command failed with exit code 1 (use -v to see invocation)

C++ compiler for the build machine: ccache c++ (clang 10.0.1 "Apple LLVM version 10.0.1 (clang-1001.0.46.3)")
C++ linker for the build machine: APPLE ld 450.3
RUNNING ['/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang', '-Wl,--version']
ld: unknown option: --version
clang: error: linker command failed with exit code 1 (use -v to see invocation)

C compiler for the host machine: /Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang (clang 8.0.7 "Android (5220042 based on r346389c) clang version 8.0.7 (https://android.googlesource.com/toolchain/clang b55f2d4ebfd35bf643d27dbca1bb228957008617) (https://android.googlesource.com/toolchain/llvm 3c393fe7a7e13b0fba4ac75a01aa683d7a5b11cd) (based on LLVM 8.0.7svn)")
C linker for the host machine: APPLE ld 450.3
RUNNING ['/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang++', '-Wl,--version']
ld: unknown option: --version
clang++: error: linker command failed with exit code 1 (use -v to see invocation)

C++ compiler for the host machine: /Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang++ (clang 8.0.7 "Android (5220042 based on r346389c) clang version 8.0.7 (https://android.googlesource.com/toolchain/clang b55f2d4ebfd35bf643d27dbca1bb228957008617) (https://android.googlesource.com/toolchain/llvm 3c393fe7a7e13b0fba4ac75a01aa683d7a5b11cd) (based on LLVM 8.0.7svn)")
C++ linker for the host machine: APPLE ld 450.3

The resulting issue, btw, is that I end up with Apple-specific flags being passed to my Android compiler, and Apple-specific file extensions being used for my libraries; I thereby end up with -dead_strip_dylibs (which isn't supported by this compiler, but is hilariously parsed as a kind of symbol to define and re-export) and .dylib. Here's an example LINK_ARGS from the resulting build.ninja (this is a compile of glib).

 LINK_ARGS = -L/Users/saurik/orchid/app-android/out-and/arm64-v8a/usr/lib -Wl,-dead_strip_dylibs -Wl,-undefined,error -Wl,-headerpad_max_install_names -shared -fPIC -install_name @rpath/libintl.dylib --sysroot=/Users/saurik/Library/Android/sdk/ndk-bundle/toolchains/llvm/prebuilt/darwin-x86_64/sysroot -fno-addrsig -target aarch64-unknown-linux-android21

[dcbaker]

Not passing the arguments in the cross file to the linker detection is very certainly a bug.

[jpakkane]

What's the status of this one? Is that branch/commit going to fix the issue or does it need more work still?

[marc-h38]

it returns the default linker for the build system instead of the chosen linker for the host system (which might be the default for a --target or might be a specific override due to -B or -fuse-ld)

BTW -fuse-ld=my_linker is worse than broken with XCode 11: it does redirects /usr/bin/clang to my_linker yet keeps passing ld64 specific options like -macosx_version_min 123 or -lto_library something.dylib. Now I think you were likely not considering that particular front-end but that took me a while to realize because of the similarities.

#6063 (comment)

[dcbaker]

Ok, I've changed approaches and things seem to be working much better. I still need to implement the fix for windows/msvc.

[dcbaker]

and write some tests and error handling.

[jpakkane]

@saurik can you test if #6207 fixes this for you?

[dcbaker]

As a note, you can work around this right now with symlinks, clang understands that i686-linux-gnu-clang is the same as clang --target=i686-linux-gnu, for those that might be hitting this right now.

[dcbaker]

I've moved this from 0.52.2 to 0.53.0, as (I think) we've decided the size of the changes are too large to go into a stable release. There's a bunch of other linker related stuff in the 0.53.0 milestone now.

[ylatuya]

I can reproduce the same issue after upgrading to 0.52.0 that I needed for macOS Catalina fixes.
Is there any workaround to fix to miss-detection of the linker as APPLE LD ?

I tried the following workarounds:

1. Adding ld = ['arm-linux-androideabi-ld.gold'] in the cross file [binaries]
2. Creating a link from clang to arm-linux-androideabi-clang and using this as the c compiler in the messon cross-file.

[binaries]
c = ['/opt/android-ndk-18/toolchains/llvm/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-clang', '-target', 'armv7-none-linux-androideabi19', '--sysroot', '/opt/android-ndk-18/platforms/android-19/arch-arm']
cpp = ['/opt/android-ndk-18/toolchains/llvm/prebuilt/darwin-x86_64/bin/clang++', '-target', 'armv7-none-linux-androideabi19', '--sysroot', '/opt/android-ndk-18/platforms/android-19/arch-arm']
ar = ['arm-linux-androideabi-ar']
ld = ['arm-linux-androideabi-ld.gold']
pkgconfig = 'pkg-config'
cmake = ['false']
strip = ['arm-linux-androideabi-strip']

The linker is still miss-detected as APPLE LD

[ylatuya]

I understand I would need #6207 to override the linker in the [binaries] section.