go.rb

class Go < Formula
  desc "Open source programming language to build simple/reliable/efficient software"
  homepage "https://golang.org"
  license "BSD-3-Clause"

  # stable do
  #   url "https://golang.org/dl/go1.15.5.src.tar.gz"
  #   mirror "https://fossies.org/linux/misc/go1.15.5.src.tar.gz"
  #   sha256 "c1076b90cf94b73ebed62a81d802cd84d43d02dea8c07abdc922c57a071c84f1"
  #
  #   go_version = version.major_minor
  #   resource "gotools" do
  #     url "https://go.googlesource.com/tools.git",
  #         branch: "release-branch.go#{go_version}"
  #   end
  # end

  livecheck do
    url "https://golang.org/dl/"
    regex(/href=.*?go[._-]?v?(\d+(?:\.\d+)+)[._-]src\.t/i)
  end

  # bottle do
  #   sha256 "61f04e266ba1f69573ae46766f8988029c5a34f4ae4f1ac0951cf3daf4d919d1" => :big_sur
  #   sha256 "77f172eb6849a0f86eed4fa8eaeb9e8c69223b7f154a86505a7507b4ea78de79" => :catalina
  #   sha256 "70969a6147bad6960136bdea78063d39b527c993a725ad525a3cf6e9f8ad6fa5" => :mojave
  #   sha256 "7d39badbe6096ffd120c3e997ee16fd026d12c4037eb055d26290a39f2689582" => :high_sierra
  # end

  head do
    url "https://go.googlesource.com/go.git"

    resource "gotools" do
      url "https://go.googlesource.com/tools.git"
    end
  end

  # Don't update this unless this version cannot bootstrap the new version.
  resource "gobootstrap" do
    on_macos do
      url "https://storage.googleapis.com/golang/go1.15.5.darwin-amd64.tar.gz"
      sha256 "359a4334b8c8f5e3067e5a76f16419791ac3fef4613d8e8e1eac0b9719915f6d"
    end

    on_linux do
      url "https://storage.googleapis.com/golang/go1.15.5.linux-amd64.tar.gz"
      sha256 "9a58494e8da722c3aef248c9227b0e9c528c7318309827780f16220998180a0d"
    end
  end

  def install
    (buildpath/"gobootstrap").install resource("gobootstrap")
    ENV["GOROOT_BOOTSTRAP"] = buildpath/"gobootstrap"

    on_macos do
      # Work around bug in Rosetta 2, see:
      # https://github.com/golang/go/issues/42700
      ENV["GODEBUG"] = "asyncpreemptoff=1" if Hardware::CPU.physical_cpu_arm64?

      # Skip building a bootstrap compiler unless we build for arm64.
      next unless Hardware::CPU.arm?

      ENV["GOHOSTARCH"] = "#{Hardware::CPU.arch}"
      ENV["CGO_ENABLED"] = "1"
      # Write CC wrapper with proper arch otherwise CGO build will fail.
      (buildpath/"cc_target").write <<~EOS
        #!/bin/sh
        exec "#{ENV["CC"]}" -arch "#{Hardware::CPU.arch}" "$@"
      EOS
      chmod "+x", "cc_target"
      ENV["CC_FOR_TARGET"] = buildpath/"cc_target"
    end

    cd "src" do
      ENV["GOROOT_FINAL"] = libexec
      system "./make.bash", "--no-clean"
    end

    (buildpath/"pkg/obj").rmtree
    rm_rf "gobootstrap" # Bootstrap not required beyond compile.
    libexec.install Dir["*"]
    bin.install_symlink Dir[libexec/"bin/go*"]

    system bin/"go", "install", "-race", "std"

    # Build and install godoc
    ENV.prepend_path "PATH", bin
    ENV["GOPATH"] = buildpath
    (buildpath/"src/golang.org/x/tools").install resource("gotools")
    cd "src/golang.org/x/tools/cmd/godoc/" do
      system "go", "build"
      (libexec/"bin").install "godoc"
    end
    bin.install_symlink libexec/"bin/godoc"
  end

  test do
    (testpath/"hello.go").write <<~EOS
      package main

      import "fmt"

      func main() {
          fmt.Println("Hello World")
      }
    EOS
    # Run go fmt check for no errors then run the program.
    # This is a a bare minimum of go working as it uses fmt, build, and run.
    system bin/"go", "fmt", "hello.go"
    assert_equal "Hello World\n", shell_output("#{bin}/go run hello.go")

    # godoc was installed
    assert_predicate libexec/"bin/godoc", :exist?
    assert_predicate libexec/"bin/godoc", :executable?

    ENV["GOOS"] = "freebsd"
    ENV["GOARCH"] = "amd64"
    system bin/"go", "build", "hello.go"
  end
end

Installs go HEAD using Homebrew for Apple M1 arm64 architecture.

Usage:

git clone https://gist.github.com/d08875fc3e1a69fe8d6eaa724829c950.git
brew install --HEAD d08875fc3e1a69fe8d6eaa724829c950/go.rb
rm -rf d08875fc3e1a69fe8d6eaa724829c950