SubmittingPatches: explain why we care about log messages

Extend the "describe your changes well" section to cover whom we are
trying to help by doing so in the first place.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano 2022-01-27 11:02:59 -08:00
parent 607817a3c8
commit cdba0295b0

View file

@ -110,6 +110,35 @@ run `git diff --check` on your changes before you commit.
[[describe-changes]]
=== Describe your changes well.
The log message that explains your changes is just as important as the
changes themselves. Your code may be clearly written with in-code
comment to sufficiently explain how it works with the surrounding
code, but those who need to fix or enhance your code in the future
will need to know _why_ your code does what it does, for a few
reasons:
. Your code may be doing something differently from what you wanted it
to do. Writing down what you actually wanted to achieve will help
them fix your code and make it do what it should have been doing
(also, you often discover your own bugs yourself, while writing the
log message to summarize the thought behind it).
. Your code may be doing things that were only necessary for your
immediate needs (e.g. "do X to directories" without implementing or
even designing what is to be done on files). Writing down why you
excluded what the code does not do will help guide future developers.
Writing down "we do X to directories, because directories have
characteristic Y" would help them infer "oh, files also have the same
characteristic Y, so perhaps doing X to them would also make sense?".
Saying "we don't do the same X to files, because ..." will help them
decide if the reasoning is sound (in which case they do not waste
time extending your code to cover files), or reason differently (in
which case, they can explain why they extend your code to cover
files, too).
The goal of your log message is to convey the _why_ behind your
change to help future developers.
The first line of the commit message should be a short description (50
characters is the soft limit, see DISCUSSION in linkgit:git-commit[1]),
and should skip the full stop. It is also conventional in most cases to