For a long time I've had this in my ~/.gitconfig:
[core]
whitespace = space-before-tab,indent-with-non-tab,trailing-space
which causes git to show me if I muck up and use spaces instead of
tabs, or leave in trailing whitespace. I find this really useful.
I recently proposed adding something like this to the .gitattributes
files for the GDB sub-directories (gdb, gdbsupport, and gdbserver)[1],
however, the question was asked - couldn't this be done at the top
level?
So, in this commit, I propose to update the top-level .gitattributes
file, after this commit, any git diff on a C, C++, Expect, or TCL
source file, will highlight the following whitespace errors:
(a) Use a space before a tab at the start of a line,
(b) Use of spaces where a tab could be used at the start of a line,
and
(c) Any trailing whitespace.
Errors are only highlighted in the diff on new or modified lines, so
you don't get spammed for errors on context lines that you haven't
modified.
The only downside I see to adding this at the top level is if there
are any sub-directories that don't follow the tabs/spaces indentation
rules very well already, in those directories you'll end up hitting
issues any time you edit a line. For GDB we're usually pretty good,
so having this highlighting isn't an issue.
[1] https://sourceware.org/pipermail/gdb-patches/2022-July/190843.html
Individual users will still have to:
1. Install git-merge-changelog
2. Set up the merge driver in their git config
See gnulib's lib/git-merge-changelog.c [1] for details.
For example, I:
1. Patched Debian's gnulib package to build git-merge-changelog, and
sent the patch to the Debian maintainer, who then proceeded to not
only accept my patch but even write a *manpage* for
git-merge-changelog! (Let's hear it for Ian Beckwith.)
So now, I can install it simply by running "apt-get install
git-merge-changelog". (Except, of course, that I already have it
installed from when I was testing my patch.)
2. Did step (2) from .gitattributes
With this patch applied and the above two steps done by whatever means
you deem best, you can say goodbye to merge conflicts in ChangeLog
files -- at least *IF* people stop renaming the danged things, anyway.
If you don't do step 2, you will continue to suffer from ChangeLog
merge conflicts exactly as before, whether or not you did step 1.
If you do step 2 but not step 1, git will likely start complaining
that it can't find any "git-merge-changelog" to run.
[1]: http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=lib/git-merge-changelog.c
[Note: The docs for git-merge-changelog (the comments at the top) say
that you need a .gitattributes in every directory. The docs are wrong.
Ignore the docs. Well, not the whole docs; just that part.
You really only need one at the top level, since .gitattributes uses
the same pattern matching rules as .gitignore, which match files in
any subdirectory unless you prefix the pattern with a "/", as
explained in the gitignore(5) manpage.]
