cmd/dist: build fails if gcc is not installed

[davecheney]

Building Go on a fresh linux/arm64 machine fails because gcc is not installed.

This might be confusing to new developers because we've made a lot of noise that we're moving away from C to Go in the 1.5 release.

The gcc build time dependency comes from cgo, and all linux/* platforms default to cgo enabled by default.

Should cmd/dist check to see if gcc (or $CC) is valid, and if not, disable cgo ?

/cc @adg @minux

[adg]

Most people want cgo support to be available. That means you need a C
compiler, and shouldn't be a surprise to anyone.

I don't see the problem with saying "If you don't have or want a C compiler
then disable cgo."

On 7 May 2015 at 10:09, Dave Cheney notifications@github.com wrote:

Building Go on a fresh linux/arm64 machine fails because gcc is not
installed.

This might be confusing to new developers because we've made a lot of
noise that we're moving away from C to Go in the 1.5 release.

The gcc build time dependency comes from cgo, and all linux/* platforms
default to cgo enabled by default.

Should cmd/dist check to see if gcc (or $CC) is valid, and if not, disable
cgo ?

/cc @adg https://github.com/adg @minux https://github.com/minux

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#10731.

[davecheney]

Fair point. Currently the build pukes in the middle of the second stage compile. Do you have strong feelings on adding a check to cmd/dist that if cgo is enabled and gcc/$CC is not found, to abort earlier ?

[adg]

It sounds like a nice user friendly thing to do.

On 7 May 2015 at 10:25, Dave Cheney notifications@github.com wrote:

Fair point. Currently the build pukes in the middle of the second stage
compile. Do you have strong feelings on adding a check to cmd/dist that if
cgo is enabled and gcc/$CC is not found, to abort earlier ?

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#10731 (comment).

[minux]

Yeah, I think we can add that check to fail earlier and given a hint to set CGO_ENABLED=0 if it's intended. Note we need to check two different cases: 1. native compilation, check $CC (if non-empty) and gcc/clang in $PATH. 2. cross compilation, check $CC_FOR_TARGET (if non-empty) in $PATH.

[bradfitz]

This actually bit me today while setting up new builders. I agree we should fail earlier, and be helpful when failing would be nice.

[gopherbot]

CL https://golang.org/cl/12146 mentions this issue.