Phases and snippets no longer returning a Boolean

["Ludovic Courtès" <ludo@gnu.org>]

Hello Guix!

As a followup to our recent discussion¹, I pushed the following commits
to ‘core-updates’:

  16111ad11c gnu: gcc: Phases no longer return a Boolean.
  3504e39a5d gnu: base, gcc: Removing trailing #t from snippets.
  325d00e619 packages: Ignore return value of origin snippets.
  4cebe82fa6 build-system/texlive: Phases no longer return a Boolean.
  49eadd270c build-system/minify: Phases no longer return a Boolean.
  112982526f gnu: base, commencement: Remove trailing #t from build phases.
  04baa011e9 build-system/gnu: Ignore the result of phase procedures.

With these changes, the return value of origin snippets and build phases
is now ignored.  It had been deprecated, with a warning emitted at build
time, since March 2018 (notably commit
daac9c77b9ed25a3c0edf843fdfe5e209ebef58f).  The introduction of ‘invoke’
(commit 3f65c190d23296e7e718c3deff413e8beb61d8ba), which would raise an
error when a program exits with non-zero, was also an enabler.  Because
of that I’m quite confident that breakage is unlikely, but we’ll keep an
eye on it.

I only removed trailing #t in a couple of files unlikely to result in
merge conflicts down the road, as Marius rightfully suggested on IRC.

That’s it!  Thoughts?  Comments?

#t!

Ludo’.

¹ https://lists.gnu.org/archive/html/guix-devel/2020-10/msg00332.html