Cross compiling for Windows

[mikong]

Environment: x86_64-apple-darwin
Target: x86_64-pc-windows-gnu

Note: Our target is x86_64-pc-windows-gnu instead of x86_64-pc-windows-msvc. The MSVC ABI is only needed if we want to interoperate with software produced by Visual Studio. It also requires Visual Studio or Visual C++ Build Tools.

We encounter the following error messages as described in rust-lang/rust#48272:

undefined reference to `__onexitend'
undefined reference to `__onexitbegin'

That issue in rust-lang/rust was closed after they added back the downloading of rust-mingw, but it doesn't help our case. We have our own MinGW and removing the linker from ~/.cargo/config will result in a linker error as described in rust-lang/rust#33465:

ld: unknown option: --enable-long-section-names
clang: error: linker command failed with exit code 1

To Reproduce

1. Install MinGW:

$ brew install mingw-w64
# Installs 6.0.0 as of writing

2. Install cross compiled standard library:

$ rustup target add x86_64-pc-windows-gnu

3. Update ~/.cargo/config:

[target.x86_64-pc-windows-gnu]
linker = "x86_64-w64-mingw32-gcc"

4. Cross compile with cargo:

$ cargo build --target=x86_64-pc-windows-gnu
$ cargo build --release --target=x86_64-pc-windows-gnu

[mikong]

For now, we can follow the solution described in one of the comments in rust-lang/rust#48272 (comment):

$ cd ~/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/x86_64-pc-windows-gnu/lib/
$ cp crt2.o crt2.o.bak
$ cp /usr/local/Cellar/mingw-w64/6.0.0/toolchain-x86_64/x86_64-w64-mingw32/lib/crt2.o .