Re: Proposal: format GDB Python files with black

[Tom Tromey <tom@tromey.com>]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> A few people I talked to about this and I have good experience
Simon> with the tool black to auto-format Python code.

Inspired by this, I took another look at clang-format.  If we could use
this, I think it would be a decent productivity improvement, because it
would mean contributors would no longer need to worry about the minutiae
of the GNU style.  We could also stop reviewing this.

My github has my current hacks, on the t/clang-format branch.  This
branch just has .clang-format, I didn't reformat the sources.  I'm using
clang-format 10.0.1.

I managed to tweak the penalty values in the format to avoid the
bin-packing problem I was seeing previously.  I haven't extensively
tested this (I usually only reformat gdb_bfd.c and look at it, since it
exercised several bugs before...), so I recommend that others play with
it a bit.

I did see a few issues, though perhaps they are minor.

1. It removes all the Control-L page breaks from the source.
   I know these often confuse newcomers, so maybe it's fine.
   I feel that Someone out there will cheer this :)

2. clang-format can't handle GNU-style goto label out-denting.
   There's a clang-format bug on this topic
   https://bugs.llvm.org/show_bug.cgi?id=24118

3. In gdb if we have a large 'if' condition that consists of expression
   chained with "&&" or "||", we often put each sub-condition on its own
   line.  clang-format packs them instead, and I didn't see a way to
   counteract this.

4. Gettext invocations like _("text") have a space added, like _ ("text").
   I didn't see a way to change this.

Another possible problem is that, unlike with 'black', ensuring that
everyone has the same version is a pain.

Maybe we could live with these?  Let me know what you think.
I can continue my experiments if this seems worthwhile.

Tom