bug#31647: [core-updates] gtkglext fails in a weird way

[Mark H Weaver <mhw@netris.org>]

Ricardo Wurmus <ricardo.wurmus@mdc-berlin.de> writes:

>> on “core-updates” the “gtkglext” package fails with an odd error
>> message: […]
>
> It seems that this is not limited to “gtkglext”.  This behaviour seems
> to affect any package using “invoke” where the invoked command fails.
>
> Should the build system catch the exception and make sure that it gets
> to print “build phase `foo' failed”?

In my opinion, it's not important for that message to be printed.  What
is being printed now is far more informative, and sometimes that extra
information is quite useful.

If we caught exceptions, we'd need to ensure that all of the relevant
information about the exception is printed.  The code to catch and print
those exceptions would need to be in (guix build ...), and it could
never be updated without forcing a full rebuild.
'call-with-error-handling' in (guix ui) might be suitable, but it would
need to be duplicated.

Also, even if we catch the exception and do a nice job printing it, we'd
likely lose the backtrace to the original error, which in some cases
might be quite useful.

In summary, although the new messages don't look as nice in common
cases, I think it's more important to ensure that we have the
information we need to debug the occasional non-obvious problem.  So, I
think we should leave it alone :)

What do you think?

      Mark