The main differentiator of xgo versus other cross compilers is support for basic embedded C/C++ code and target-platform specific OS SDK availability. The current xgo release introduces an experimental CGO dependency cross compilation, enabling building Go programs that require external C/C++ libraries.
It is assumed that the dependent C/C++ library is configure/make based, was
properly prepared for cross compilation and is available as a tarball download
(.tar, .tar.gz or .tar.bz2). Further plans include extending this to cmake
based projects, if need arises (please open an issue if it's important to you).
Such dependencies can be added via the --deps argument. They will be retrieved
prior to starting the cross compilation and the packages cached to save bandwidth
on subsequent calls.
A complex sample for such a scenario is building the Ethereum CLI node, which has the GNU Multiple Precision Arithmetic Library as it's dependency.
$ xgo --deps=https://gmplib.org/download/gmp/gmp-6.1.0.tar.bz2 --targets=windows/* github.com/ethereum/go-ethereum/cmd/geth
...
ls -al-rwxr-xr-x 1 root root 16315679 Nov 24 16:39 geth-windows-4.0-386.exe
-rwxr-xr-x 1 root root 19452036 Nov 24 16:38 geth-windows-4.0-amd64.exe
Some trivial arguments may be passed to the dependencies' configure script via --depsargs.
xgo --deps=https://gmplib.org/download/gmp/gmp-6.1.0.tar.bz2 --targets=ios/* --depsargs=--disable-assembly github.com/ethereum/go-ethereum/cmd/geth
...
ls -al-rwxr-xr-x 1 root root 14804160 Nov 24 16:32 geth-ios-5.0-arm
Note, that since xgo needs to cross compile the dependencies for each platform and architecture separately, build time can increase significantly.