Commit messages and the move to git

Segher Boessenkool
Mon Nov 18 19:44:00 GMT 2019

On Mon, Nov 18, 2019 at 07:21:22PM +0000, Richard Earnshaw (lists) wrote:
> On 18/11/2019 18:53, Segher Boessenkool wrote:
> > PR target/92140: clang vs gcc optimizing with adc/sbb
> > PR fortran/91926: assumed rank optional
> > PR tree-optimization/91532: [SVE] Redundant predicated store in
> > PR tree-optimization/92161: ICE in vect_get_vec_def_for_stmt_copy, at tree-vect-stmts.c:1687
> > PR tree-optimization/92162: ICE in vect_create_epilog_for_reduction, at tree-vect-loop.c:4252
> > PR c++/92015: internal compiler error: in cxx_eval_array_reference, at cp/constexpr.c:2568
> > PR tree-optimization/92173: ICE in optab_for_tree_code, at optabs-tree.c:81
> > PR tree-optimization/92173: ICE in optab_for_tree_code, at optabs-tree.c:81
> > PR fortran/92174: runtime error: index 15 out of bounds for type 'gfc_expr *[15]
> > 
> > Most of these aren't helpful at all, and none of these are good commit
> > summaries.  The PR92173 one actually has identical commit messages btw,
> > huh.  Ah, the second one (r277288) has the wrong changelog, but in the
> > actual changelog file as well, not something any tool could fix up (or
> > have we reached the singularity?)
> Identical commits are normally from where the same commit is made to
> multiple branches.  It's not uncommon to see this when bugs are fixed.

This is an actual mistake.  The commits are not identical at all, just
the commit messages are (and the changelog entries, too).  Not something
that happens to ften, but of course I hit it in the first random thing I
pick :-)

> Ultimately the question here is whether something like the above is more
> or less useful than what we have today, which is summary lines of the form:
> <date> <user> <email>

I already said I would prefer things like
  Patch related to PR323
as the patch subject lines.  No one argues that the current state of
affairs is good.  I argue that replacing this with often wrong and
irrelevant information isn't the best we can do.

> I think the above is just useless since it duplicates information
> already in the short summaries, and unless we have an extraordiarily
> high error rate, a summary based on the bugzilla entry is more likely to
> be useful than that, even if it is far from perfect.

I don't agree with this part, that is all.

> None of this would be necessary, of course, if we had good short
> summaries already for every commit, which is why I'd like EVERYONE to
> start doing that NOW, rather than waiting for the conversion to happen.

And not just a subject line, also a little bit of substance in the
commit message body text please, before the changelog.


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