Rust Crosscompiling on Linux

Tested on Manjaro Linux 5.6.12 (2020-05-26).

Rust

Install native Linux rust and i686-pc-windows-gnu target.

Currently (as of 2020-05) Windows version of cargo doesn’t run on Wine (NtLockFile from ntdll is not implemented). Rustc alone seems to be working. Fortunately, you can use linux version of rustc and cargo with i686-pc-windows-gnu target installed.

GCC (option 1 - Linux binaries)

You can install mingw-w64-gcc natively on Linux. Make sure that the i686 version is configured with dwarf2 exception handling. Otherwise, it won’t link the rust code. Also install i686-w64-mingw32-wine package.

Look at the PKGBUILD (you need to also verify it for every library). Make sure there are flags:

--disable-sjlj-exceptions --with-dwarf2

However, the sjlj version may also work (not tested) if you add rustflags to the .cargo/config:

[target.i686-pc-windows-gnu]
rustflags = "-C panic=abort"

Add to your .cargo/config:

[target.i686-pc-windows-gnu]
linker = "/usr/bin/i686-w64-mingw32-gcc"
ar = "/usr/i686-w64-mingw32/bin/ar"
runner = "/usr/bin/i686-w64-mingw32-wine"
rustflags = [
            ]

[target.x86_64-pc-windows-gnu]
linker = "/usr/bin/x86_64-w64-mingw32-gcc"
ar = "/usr/x86_64-w64-mingw32/bin/ar"
runner = "/usr/bin/x86_64-w64-mingw32-wine"
rustflags = [
            ]

GCC (option 2 - Windows binaries)

It works through Wine.

You can either download gcc from: https://sourceforge.net/projects/mingw-w64/files/Toolchains%20targetting%20Win32/Personal%20Builds/mingw-builds/. Tested with i686-8.1.0-release-posix-dwarf-rt_v6-rev0.7z.

Or you can install msys2-i686 from: https://sourceforge.net/projects/msys2/files/Base/i686/. The only problem with it is that bash and pacman commands are crashing on Wine, but the gcc compiler works great. And it is very easy to install libraries. So this is a great option if you can update and install libraries from real Windows.

Let’s assume you’ve installed msys2-i686 somewhere in msys2-x32 folder. Now you can create following scripts at the same level:

wine-mingw-command.sh - base script to call GCC tools:

#!/bin/bash

# folders
BASE_DIR=$(dirname $0)
MSYS_DIR=$BASE_DIR/msys2-x32
MINGW_DIR=$MSYS_DIR/mingw32

# GCC
export WINEPATH=$MINGW_DIR/bin
export CC=i686-w64-mingw32-gcc
export CXX=i686-w64-mingw32-g++
export AR=i686-w64-mingw32-ar

# make sure that crt2.o come from MINGW_DIR
# cargo is trying to use it's own version which won't work
declare -a new_args=()
for var in "${@:2}"
do
	if [[ "$var" == */lib/crt2.o ]]
	then
		new_args+=("$MINGW_DIR/i686-w64-mingw32/lib/crt2.o")
	elif [[ "$var" == */lib/dllcrt2.o ]]
	then
		new_args+=("$MINGW_DIR/i686-w64-mingw32/lib/dllcrt2.o")
	else
		new_args+=($var)
	fi
done

# call command provided as the first parameter
$MINGW_DIR/bin/$1 "${new_args[@]}"

wine-runner.sh - allows to run final .exe files with access to all required dlls:

#!/bin/bash

# folders
BASE_DIR=$(dirname $0)
MSYS_DIR=$BASE_DIR/msys2-x32
MINGW_DIR=$MSYS_DIR/mingw32

# GCC
export WINEPATH=$MINGW_DIR/bin

/usr/bin/wine "$@"

Now you are ready to create following shortcuts. Put them somewhere that they are available in one of the PATH environment’s folder. For example in `~/.cargo/bin”. The scripts are:

i686-w64-mingw32-ar:

/mnt/aplikacje/Uzytkowe/dev/compilers/native-x32/wine-mingw-command.sh ar.exe "$@"

i686-w64-mingw32-g++:

/mnt/aplikacje/Uzytkowe/dev/compilers/native-x32/wine-mingw-command.sh g++.exe "$@"

i686-w64-mingw32-gcc:

/mnt/aplikacje/Uzytkowe/dev/compilers/native-x32/wine-mingw-command.sh gcc.exe "$@"

i686-w64-mingw32-pkg-config:

/mnt/aplikacje/Uzytkowe/dev/compilers/native-x32/wine-mingw-command.sh pkg-config.exe "$@"

Note! I had problems with building freetype for rust when I rename i686-w64-mingw32-ar to i686-w64-mingw32-gcc-ar. The reason is not clear to me and it is related with cmake that cannot find ar command.

Finally, you can update cargo configuration in ~/.cargo/config file:

[target.i686-pc-windows-gnu]
linker = "i686-w64-mingw32-gcc"
ar = "i686-w64-mingw32-ar"
runner = "/mnt/aplikacje/Uzytkowe/dev/compilers/native-x32/wine-runner.sh"
rustflags = [
            ]