Bug 13866

All Go compiler versions > 1.4.x (old) are written in Go, and require a existing compiled Go version to use to build from source.

https://golang.org/doc/install/source#bootstrapFromSource

The process for "bootstrapping" the Go compiler in Buildroot is:

1. Compile a C/C++ cross-compiler (gcc) as the host toolchain.
2. Build go-bootstrap (which is Go 1.4.x and written in C)
3. Build go 1.16.x (written in Go) using go-bootstrap.

The problem is that step 2 - build go-bootstrap - does not work on 64-bit arm. The Go compiler from 1.4.x is compatible with x86, x86_64, and arm (32 bit) only.

This means that arm64 host machines will skip building Go and all go-based packages like Docker.

Due to BR2_PACKAGE_HOST_GO_BOOTSTRAP_ARCH_SUPPORTS

The best fix to this for Buildroot is to continue using go-bootstrap on x86_64 or arm32 platforms (when BR2_PACKAGE_HOST_GO_BOOTSTRAP_ARCH_SUPPORTS is set). This is the most flexible option in terms of supporting third-party toolchains to bootstrap Go.

Support for gccgo (the Go compiler built-in to GCC 5 and greater) should be added with a conditional flag for the Buildroot toolchain (which would set --enable-languages=go).

If the compiler supports gccgo (toolchain sets GCCGO_SUPPORTS) flag, and GO_BOOTSTRAP_ARCH_SUPPORTS is false, then the host-go package should use the toolchain Gccgo to compile the Go compiler.

The toolchain gccgo would install a "go" binary into the host tree provided by gcc. (This binary is drop-in compatible with the normal Go compiler).

The Go compiler can then be instructed to use gccgo by simply setting $GOROOT_BOOTSTRAP to host/usr.