code review 100390043: cmd/cgo: document CC_FOR_TARGET and CXX_FOR_TARGET

cmd/cgo: document CC_FOR_TARGET and CXX_FOR_TARGET

Update issue 4714

[elias.naur, 2014-05-11 20:36:44]

Hello rsc@golang.org (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go

[iant, 2014-05-12 05:01:21]

https://codereview.appspot.com/100390043/diff/60001/doc/go1.3.html
File doc/go1.3.html (right):

https://codereview.appspot.com/100390043/diff/60001/doc/go1.3.html#newcode180
doc/go1.3.html:180: variables are used to specify the cross compilers for C and
C++ code,
I think you need to say something like "are used when running all.bash".

https://codereview.appspot.com/100390043/diff/60001/src/cmd/cgo/doc.go
File src/cmd/cgo/doc.go (right):

https://codereview.appspot.com/100390043/diff/60001/src/cmd/cgo/doc.go#newcode67
src/cmd/cgo/doc.go:67: environment variable is set to 1. In that case, use
CC_FOR_TARGET
Similarly, use CC_FOR_TARGET when running make.bash.

[elias.naur, 2014-05-12 08:29:17]

PTAL

On 2014/05/12 05:01:21, iant wrote:
> https://codereview.appspot.com/100390043/diff/60001/doc/go1.3.html
> File doc/go1.3.html (right):
> 
> https://codereview.appspot.com/100390043/diff/60001/doc/go1.3.html#newcode180
> doc/go1.3.html:180: variables are used to specify the cross compilers for C
and
> C++ code,
> I think you need to say something like "are used when running all.bash".
> 

Done.

> https://codereview.appspot.com/100390043/diff/60001/src/cmd/cgo/doc.go
> File src/cmd/cgo/doc.go (right):
> 
>
https://codereview.appspot.com/100390043/diff/60001/src/cmd/cgo/doc.go#newcode67
> src/cmd/cgo/doc.go:67: environment variable is set to 1. In that case, use
> CC_FOR_TARGET
> Similarly, use CC_FOR_TARGET when running make.bash.

Done.

[iant, 2014-05-12 16:16:33]

https://codereview.appspot.com/100390043/diff/70001/src/cmd/cgo/doc.go
File src/cmd/cgo/doc.go (right):

https://codereview.appspot.com/100390043/diff/70001/src/cmd/cgo/doc.go#newcode66
src/cmd/cgo/doc.go:66: Cgo is disabled when cross compiling, unless the
CGO_ENABLED
Check me on this, but I think this is incomplete.

When running make.bash, the environment variable CC_FOR_TARGET is used during
the build and it becomes the default compiler used by cgo.

After the Go tools are built, when running the go command, CC_FOR_TARGET is
ignored.  The value of CC_FOR_TARGET when running make.bash is the default
compiler.  However, you can set the environment variable CC, not CC_FOR_TARGET,
to control the compiler when running the go tool.

[elias.naur, 2014-05-12 19:05:06]

PTAL

On 2014/05/12 16:16:33, iant wrote:
> https://codereview.appspot.com/100390043/diff/70001/src/cmd/cgo/doc.go
> File src/cmd/cgo/doc.go (right):
> 
>
https://codereview.appspot.com/100390043/diff/70001/src/cmd/cgo/doc.go#newcode66
> src/cmd/cgo/doc.go:66: Cgo is disabled when cross compiling, unless the
> CGO_ENABLED
> Check me on this, but I think this is incomplete.
> 
> When running make.bash, the environment variable CC_FOR_TARGET is used during
> the build and it becomes the default compiler used by cgo.
> 
> After the Go tools are built, when running the go command, CC_FOR_TARGET is
> ignored.  The value of CC_FOR_TARGET when running make.bash is the default
> compiler.  However, you can set the environment variable CC, not
CC_FOR_TARGET,
> to control the compiler when running the go tool.

You're right of course, thanks. I've rephrased the description using your
wording.

[iant, 2014-05-12 19:31:48]

LGTM

Please wait for r or rsc to take a look.

[minux1, 2014-05-12 22:26:38]

LGTM.

I must say I still don't like the CC_FOR_TARGET name:
it's too verbose.

[rsc, 2014-05-13 03:20:08]

LGTM

I am not terribly happy about the names either but they do seem to be somewhat
standard as far as Unix cross compilation goes and there's something to be said
for that.

https://codereview.appspot.com/100390043/diff/110001/src/cmd/cgo/doc.go
File src/cmd/cgo/doc.go (right):

https://codereview.appspot.com/100390043/diff/110001/src/cmd/cgo/doc.go#newco...
src/cmd/cgo/doc.go:68: Also, set CC_FOR_TARGET to the C cross compiler for
GOARCH.  CC will
This paragraph makes it sound like you can't do operating system
cross-compiling.
s/GOARCH/the target/.
s/GOHOSTARCH/the host/ on the next line.

[rsc, 2014-05-13 03:20:31]

Fixes issue 4714, right?

[elias.naur, 2014-05-13 07:59:47]

PTAL

On 2014/05/13 03:20:08, rsc wrote:
> LGTM
> 
> I am not terribly happy about the names either but they do seem to be somewhat
> standard as far as Unix cross compilation goes and there's something to be
said
> for that.
> 
> https://codereview.appspot.com/100390043/diff/110001/src/cmd/cgo/doc.go
> File src/cmd/cgo/doc.go (right):
> 
>
https://codereview.appspot.com/100390043/diff/110001/src/cmd/cgo/doc.go#newco...
> src/cmd/cgo/doc.go:68: Also, set CC_FOR_TARGET to the C cross compiler for
> GOARCH.  CC will
> This paragraph makes it sound like you can't do operating system
> cross-compiling.
> s/GOARCH/the target/.
> s/GOHOSTARCH/the host/ on the next line.

Done.

> Fixes issue 4714, right?

AFAIK, make.bat (and make.rc) needs updating for the new environment variables
to work.

[rsc, 2014-05-20 05:30:37]

LGTM

[rsc, 2014-05-20 05:32:33]

*** Submitted as https://code.google.com/p/go/source/detail?r=07c77d128740 ***

cmd/cgo: document CC_FOR_TARGET and CXX_FOR_TARGET

Update issue 4714

LGTM=iant, minux.ma, rsc
R=rsc, iant, r, minux.ma
CC=golang-codereviews
https://codereview.appspot.com/100390043

Committer: Russ Cox <rsc@golang.org>