"ld: unknown option: -plugin" when cross-compiling Linux -> OSX as of 1.27.0

[yrashk]

I have been previously cross-compiling my project using osxcross (sit-fyi/sit@8d9c368#diff-beb069f53b3284f57ea9b6fc9ffcad99) and it was working fine until I switched it to 1.27.2 (https://github.com/sit-fyi/sit/blob/5cf5059326f910f56664286dfe4ff63357cd5026/build-tools/cross-compile-osx/Dockerfile)

It now fails to compile with ld: unknown option: -plugin. I've tried 1.27.0 and it produces the same error.

Not sure if this would be considered a regression, but in case if it would, I wanted to raise attention to it. Also, is there any way to work around this?

[sfackler]

This line seems pretty suspicious:

RUN ln -s /osxcross/target/bin/x86_64-apple-darwin15-ld  /osxcross/target/bin/ld

It's going to cause the cross linker used as the host linker for things like build scripts which is not going to work.

[yrashk]

@sfackler Steven, thank you for your feedback.

I wondered about that, too, however that was the only way back then to make everything work on 1.26 -- or, rather, the only one I found to work at the time. Perhaps, something changed in 1.27 that rendered that hack useless. If I disable it, compiling backtrace-sys crate fails with

warning: x86_64-apple-darwin15-ranlib: warning for library: .libs/libbacktrace.a the table of contents is empty (no object file members in the library define global symbols)
objcopy:/sit/target/release/build/backtrace-sys-b8cd9e70ead7da52/out/__tmp/__.SYMDEF SORTED: File format not recognized

I will keep investigating, hopefully there's the right combination that can make it work on 1.27. Thank you for your time and pinpointing the culprit, again.

[sfackler]

Here's the set of environment variables that I've found works for Linux -> OSX cross compilation:

ENV CC_x86_64-apple-darwin=x86_64-apple-darwin15-clang \
    CXX_x86_64-apple-darwin=x86_64-apple-darwin15-clang++ \
    AR_x86_64-apple-darwin=x86_64-apple-darwin15-ar \
    CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER=x86_64-apple-darwin15-clang

The first 3 in particular are probably the ones that will fix the libbacktrace issue. My guess is that it was using the host ar which produced an archive that the OSX ranlib can't understand.

[yrashk]

Thank you. After some experimentation, this seems to have worked:

FROM rust:1.27.2
RUN apt-get update && apt-get install -y clang autotools-dev automake cmake libfuse-dev fuse git
RUN rustup target add x86_64-apple-darwin
RUN git clone https://github.com/tpoechtrager/osxcross && cd osxcross && git checkout 1a1733a
COPY MacOSX10.11.sdk.tar.xz /osxcross/tarballs/
RUN cd osxcross && UNATTENDED=1 OSX_VERSION_MIN=10.7 ./build.sh
ENV PATH="/osxcross/target/bin:$PATH"
ENV CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER x86_64-apple-darwin15-clang
ENV CC_X86_64_APPLE_DARWIN_LINKER x86_64-apple-darwin15-clang
ENV CC x86_64-apple-darwin15-cc
ENV CMAKE_C_LINK_EXECUTABLE x86_64-apple-darwin15-ld
ENV CMAKE_C_COMPILER_EXTERNAL_TOOLCHAIN x86_64-apple-darwin15-cc
ENV CMAKE_C_COMPILER x86_64-apple-darwin15-cc