RFC: Better commit messages for libstdc++

[Jonathan Wakely]

On 30/09/19 15:01 +0100, Jonathan Wakely wrote:
>Proposed format:
>
>PR libstdc++/NNNNN one-line summary of the change
>
>Optional additional text describing the change here. You can use this
>to describe the problem being solved, and how the patch addresses it.
>This can be as long or short as you like, in multiple paragraphs if
>you want (or omitted entirely if there's nothing useful that isn't
>already said by the summary line and the changelog).
>
>   YYYY-MM-DD  John Doe  <jdoe@example.com>

I forgot to say that the date and committer line of the changelog is
optional in the commit message (but not in the ChangeLog file,
obviously).

If you're committing your own patch, that info is already shown by Git
(we'll have better committer info shown after the conversion, rather
than just a login name and numeric ID created by git-svn):

Author: redi <redi@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Mon Sep 30 11:52:08 2019 +0000

    Implement LWG 3255 for std::span constructors
    
    Also fix the constraints on span(Container&) and span(const Container&)
    constructors so that they aren't used for const spans or const arrays.
    
            * include/std/span (span(element_type(&)[N]))
            (span(array<value_type, N>&), span(const array<value_type, N>&)):
            Deduce array element type to allow safe const conversions (LWG 3255).
            [!_GLIBCXX_P1394] (span(Container&), span(const Container&)): Use
            remove_cv_t on arguments to __is_std_span and __is_std_array.
            * testsuite/23_containers/span/lwg3255.cc: New test.
    

If you're committing somebody else's patch, you should not omit that
line.