Re: Guix build output insufficient

[Ricardo Wurmus <rekado@elephly.net>]

Hi Danny,

> On Tue, 11 Sep 2018 13:52:16 +0200
> Ricardo Wurmus <rekado@elephly.net> wrote:
>
>> The build logs are stored by the daemon.  You can get their location by
>> doing
>> 
>>     guix build --log-file something
>
> Does this also work for failed builds - without rebuilding it again?

It does seem to work.  To test this I added (error "foo") to a build
phase in the “diamond” package and ran

   guix package -i diamond

This ends with

   Build failed:  /gnu/store/wk9qbhmdzs62mp40casrndcgm3p50m3b-diamond-0.9.22.drv
   guix package: error: build failed: build of `/gnu/store/wk9qbhmdzs62mp40casrndcgm3p50m3b-diamond-0.9.22.drv' failed

So I ran

   guix build --log-file /gnu/store/wk9qbhmdzs62mp40casrndcgm3p50m3b-diamond-0.9.22.drv

which gave me

   /var/log/guix/drvs/wk/9qbhmdzs62mp40casrndcgm3p50m3b-diamond-0.9.22.drv.bz2

which contains the build log for this failed build, including the "foo"
error message.

I would like this error log file location to be shown unprompted, but I
think we would need to change build.cc, so that BuildError prints it in
addition to the error message.

(That’s nothing that the build-output-port should try to do on its own,
in my opinion, because it really just transforms output lines.)

-- 
Ricardo