go: Allow building the cross-compilers and runtime support for other platforms.

[fd]

When the --cross-compile option is used the following runtimes will be build:

• darwin (386, amd64; with CGO)
• linux (386, amd64, arm)
• freebsd (386, amd64)
• openbsd (386, amd64)
• plan9 (386)
• windows (386, amd64)

[MikeMcQuaid]

Do we really have to build e.g. plan9 cross-compilers? I'd suggest just doing either per-platform or just the common platforms (linux, windows) for now. Thanks!

[fd]

I could make it like this:

Option 1: --cross-compile-common:

• darwin (386, amd64; with CGO)
• linux (386, amd64, arm)
• windows (386, amd64)

Option 2: --cross-compile-all:

• darwin (386, amd64; with CGO)
• linux (386, amd64, arm)
• freebsd (386, amd64)
• openbsd (386, amd64)
• plan9 (386)
• windows (386, amd64)

[fd]

pull?

[jacknagel]

ENV['GOROOT_FINAL'] = ...
ENV['GOOS'] = ...
...

system "./make.bash ...

[jacknagel]

This feels overly-complex. @MikeMcQuaid?

[MikeMcQuaid]

Yes, it's pretty unreadable to me. So you need to rerun make for each available cross-compiler? I still don't think I can really see a need for more than just Linux and Windows cross-compilation and even then if it's going to make a mess I'd rather just leave it out.

You could take the current, default darwin case out of the loop and then just iterate over Windows and Linux archs putting the prefix outside the loop and scrapping CGO_ENABLED for the loop.

[fd]

• Yes, you need to run make for each cross-compiler (unless you just want to build the host-compiler).
• darwin is the default option; no mess there.
• I need the other cross-compilers; so I added them as options. Otherwise I need to install them anyways, in the GOROOT (which in the Homebrew prefix); this is a far bigger mess.
• CGO_ENABLED is enabled by default (and should be for Darwin) but it can't be compiled for the cross-compilers. So it needs to be turned off (for the other compilers).

[MikeMcQuaid]

I think the question is how many other people are going to use how many other cross-compilers? It's very easy to fork and install your own version of this formula so we need to find a balance between what you'll use and what others will.

I'm tempted to just leave this open for a while and see if we get any other people saying "+1" in here with what cross-compilers they want.

[jmibanez]

Related to this: I've been building the cross-compilation stuff manually using ./make.bash inside $GOROOT/src; however, I've had to disable the last step of the install (include.rmtree) (which removes the include fils both in the target and inside $GOROOT). Without that last step, building the cross-compilation toolchain works; with it, you'll have to do the build from the install (just as the pull request). In other words, I also replaced line 31, same as the pull request here.

Maybe just add a caveat describing how to build the cross-compilation toolchain for a particular architecture? Personally, I need just windows-386 and linux-arm and don't care about the other targets.

[fd]

@jmibanez This pull request also fixes that problem (see #12457) (by building the cross-compilers when installing golang)

[riobard]

Any progress on this one?

[adamv]

Needs to at least be squashed and rebased on master.

[fd]

@adamv squashed and rebased.

[bjeanes]

Since this is still open to gauge support, I'll put my 👍 here. I would need, at minimum, linux (all archs), both BSDs (all archs) and eventually windows.

[MikeMcQuaid]

I'm happy with this as-is. If no-one has merged later I will; on a train with poor internet.

[bjeanes]

I just tried re-installing Go with --cross-compile-all. It failed with:

$  brew install go --cross-compile-all
==> Downloading http://go.googlecode.com/files/go1.0.3.src.tar.gz
Already downloaded: /Library/Caches/Homebrew/go-1.0.3.tar.gz
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
image/draw
image/jpeg
debug/dwarf
crypto/des
index/suffixarray

READ THIS: https://github.com/mxcl/homebrew/wiki/troubleshooting

zsh: exit 1     brew install go --cross-compile-all
4:54.51s total, 631.90s user, 106.50s system, 250% cpu

I am yet to find where any additional logs will be to see what actually caused it to fail. I do have a few brew doctor things to look into, but a Go installs successfully without the full cross-compilations.

Can anybody else confirm that things install as they expect?

[bjeanes]

Installing with --cross-compile-common just completed successfully. It seems to be just the larger set that is failing (and I am not yet sure why).

Output from successful build:

$ brew install go --cross-compile-common
==> Downloading http://go.googlecode.com/files/go1.0.3.src.tar.gz
Already downloaded: /Library/Caches/Homebrew/go-1.0.3.tar.gz
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> ./make.bash --no-clean
==> Caveats
Bash completion has been installed to:
  /usr/local/etc/bash_completion.d
/usr/local/Cellar/go/1.0.3: 4204 files, 484M, built in 3.4 minutes
3:23.72s total, 460.18s user, 75.87s system, 263% cpu

[fd]

It appears that image/jpeg started failing on plan9 after 1.0.3
I will disable plan9 for now

[joeshaw]

Building with --cross-compile-common (and probably also --cross-compile-all) seems to break cgo-required pieces in the class libraries. See issue #17758 about that.