code review 149720043: cmd/go: prohibit C sources files unless using cgo

cmd/go: prohibit C sources files unless using cgo

Those C files would have been compiled with 6c.
It's close to impossible to use C correctly anymore,
and the C compilers are going away eventually.
Make them unavailable now.

go1.4.txt change in CL 145890046

[rsc, 2014-09-19 03:50:52]

Hello iant (cc: golang-codereviews@googlegroups.com, r),

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

[iant, 2014-09-19 14:44:01]

LGTM

[rsc, 2014-09-24 19:10:44]

*** Submitted as https://code.google.com/p/go/source/detail?r=19aadfae8426 ***

cmd/go: prohibit C sources files unless using cgo

Those C files would have been compiled with 6c.
It's close to impossible to use C correctly anymore,
and the C compilers are going away eventually.
Make them unavailable now.

go1.4.txt change in CL 145890046

LGTM=iant
R=iant
CC=golang-codereviews, r
https://codereview.appspot.com/149720043

[josharian, 2014-09-24 19:46:00]

Build breakage emails appear to still be off. In lieu of that:

This broke all the linux builders.

http://build.golang.org/log/5cee68acd62c4ad8074fa8392490884b65f0e264

# ../misc/cgo/testcdefs
can't load package: package .: C source files not allowed when not using cgo:
cdefstest.c main.c
Build complete, duration 2m57.521103703s. Result: error: exit status 1

[bradfitz, 2014-09-24 20:00:36]

On Wed, Sep 24, 2014 at 12:46 PM, <josharian@gmail.com> wrote:

> Build breakage emails appear to still be off. In lieu of that:
>
> This broke all the linux builders.
>

All the cgo linux builders.  linux-amd64-nocgo is still good.  (that is:
yay it did something useful)

[rsc, 2014-09-24 21:38:23]

On Wed, Sep 24, 2014 at 4:00 PM, Brad Fitzpatrick <bradfitz@golang.org>
wrote:

> All the cgo linux builders.  linux-amd64-nocgo is still good.  (that is:
> yay it did something useful)
>

I broke that one too eventually. Working on it...

[rsc, 2014-09-24 23:26:28]

Okay, I think most things are happy now. Stopping for tonight. If someone
wants to figure out why Plan 9 is unhappy go for it.