formula: set GOPATH

[dawidd6]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

This change can speed up subsequent builds of formulae using Go Modules.
I think for us, the benefit could be: quicker go formula builds on CI or quicker local rebuilds of formulae when applying some changes.

Ideally we would wait for: golang/go#34527

and then just set GOMODCACHE, which will be a better choice instead of GOPATH.

[jonchang]

Looks like GOMODCACHE will be part of Go 1.15, which is due out on August 1: https://lwn.net/Articles/820217/

[MikeMcQuaid]

Probably makes sense to set this in

brew/Library/Homebrew/formula.rb

Lines 1797 to 1808 in d0821de

	test_env = {
	CURL_HOME: ENV["CURL_HOME"] || ENV["HOME"],
	TMPDIR: HOMEBREW_TEMP,
	TEMP: HOMEBREW_TEMP,
	TMP: HOMEBREW_TEMP,
	TERM: "dumb",
	PATH: PATH.new(ENV["PATH"], HOMEBREW_PREFIX/"bin"),
	HOMEBREW_PATH: nil,
	_JAVA_OPTIONS: "#{ENV["_JAVA_OPTIONS"]&.+(" ")}-Duser.home=#{HOMEBREW_CACHE}/java_cache",
	GOCACHE: "#{HOMEBREW_CACHE}/go_cache",
	CARGO_HOME: "#{HOMEBREW_CACHE}/cargo_cache",
	}

(grep for GOCACHE).

[dawidd6]

If I understood correctly, those ENV variables in formula.rb are only set for the test. I want set it for build too.

[MikeMcQuaid]

If I understood correctly, those ENV variables in formula.rb are only set for the test. I want set it for build too.

Nope, the def stage is set at build-time (which is what we want done here too).

[dawidd6]

Oh, I was looking at def run_test.

[MikeMcQuaid]

Worth setting in run_test too or is it basically never going to be used there?

[dawidd6]

Umm, I don't think we run any go command often in test blocks.

[MikeMcQuaid]

np, shipit!

[dawidd6]

Note for the future generation. With the release of Go 1.15, we should change GOPATH to GOMODCACHE.