I wanted to contribute to the Go source (the programming language itself) but that meant I needed to have two go versions on my machine - the one I am using currently (1.8.1) and the HEAD. This is a post explaining how to achieve that. Please note that I am on Linux and I am not using gvm for installing Go.

Get the source code

You need to get the Go source code first, of course. The Go team has excellent instructions here. Essentially you need to checkout the source repo anywhere outside your GOPATH.

$ git clone https://go.googlesource.com/go

Next, you’ll need to build this version of Go.

$ cd go/src && ./all.bash

Oh no! Errors!

Sadly, for me, this lead to an error as shown below:

##### Building Go bootstrap tool.
cmd/dist
ERROR: Cannot find /home/nikhita/go1.4/bin/go.
Set $GOROOT_BOOTSTRAP to a working Go tree >= Go 1.4.

But hey, I was already on Go 1.8.1! So I needed to set $GOROOT_BOOTSTRAP environment variable to point to the Go 1.8.1 binary. This error occurs because it defaults to $GOROOT if not specified and my $GOROOT is also not set (since I don’t have a custom installation). Oops.

The simple fix:

$ export GOROOT_BOOTSTRAP=/usr/local/go

Build the binary using ./all.bash again. It should work now!

Aliasing

You have two Go binaries installed on your machine now. Yay! But now what? How should you decide which version needs to be invoked when you run go version?

In my case, I had 1.8.1 installed already and it’s binary was already in my $PATH so this was my default version.

$ go version
go version go1.8.1 linux/amd64

To invoke your new, shiny Go binary from HEAD, you’ll need to use go/bin/go version where you installed the source repo. It’s better to alias this so that you won’t have to repeat this every time. Add something like this in your .zshrc/.bashrc/what-have-you - alias godev=/home/nikhita/go-dev/go/bin/go. Now when you run:

$ godev version
go version devel +8ec7a39fec Sat Jun 24 00:54:01 2017 +0000 linux/amd64

Viola!