HOW TO COMMIT CHANGES TO EMACS

Most of these points are from:

http://lists.gnu.org/archive/html/emacs-devel/2009-03/msg00555.html
From: 	 Miles Bader
Subject: commit style redux
Date: 	 Tue, 31 Mar 2009 12:21:20 +0900

(0) Each commit should correspond to a single change (whether spread
    over multiple files or not).  Do not mix different changes in the
    same commit (eg adding a feature in one file, fixing a bug in
    another should be two commits, not one).

(1) Commit all changed files at once with a single log message (which
    in CVS will result in an identical log message for all committed
    files), not one-by-one.  This is pretty easy using vc-dir now.

(2) Make the log message describe the entire changeset, perhaps
    including relevant changelog entries (I often don't bother with
    the latter if it's a trivial sort of change).

    Many modern source-control systems vaguely distinguish the first
    line of the log message to use as a short summary for abbreviated
    history listing (in arch this was explicitly called the summary,
    but many other systems have a similar concept).  So it's nice if
    you can format the log entry like:

        SHORTISH ONE-LINE SUMMARY

        MULTIPLE-LINE DETAILED DESCRIPTION POSSIBLY INCLUDING (OR
        CONSISTING OF) CHANGELOG ENTRIES

    [Even with CVS this style is useful, because web CVS browsing
    interfaces often include the first N words of the log message of
    the most recent commit as a short "most recent change"
    description.]

(3) Don't phrase log messages assuming the filename is known, because
    in non-file-oriented systems (everything modern other than CVS),
    the log listing tends to be treated as global information, and the
    connection with specific files is less explicit.

    For instance, currently I often see log messages like "Regenerate";
    for modern source-control systems with a global log, it's better to
    have something like "Regenerate configure".

(4) (Added in 2014) In commit comments, and ChangeLog files, it is best
    to use ways of identifying revisions that are not dependent on a
    particular version control system.  (At time of writing Emacs is
    about to move to its fourth VCS and another move in the future is
    not impossible.)  An excellent way to identify commits is by
    quoting their summary line.  Another is with an action stamp - an
    RFC3339 date followed by ! followed by the committer's email - for
    example, "2014-01-16T05:43:35Z!esr@thyrsus.com". Often, "my
    previous commit" will suffice.

Followup discussion:
http://lists.gnu.org/archive/html/emacs-devel/2010-01/msg00897.html
http://lists.gnu.org/archive/html/emacs-devel/2010-02/msg00401.html


PREVIOUS GUIDELINES FOR CVS

For historical interest only, here is the old-style advice for CVS logs:
http://lists.gnu.org/archive/html/emacs-devel/2007-12/msg01208.html

From: Eli Zaretskii
Subject: Re: Log messages in CVS
Date: Sat, 29 Dec 2007 16:06:29 +0200