diffutils file mode (was Re: [PATCH 5.15 00/37] 5.15.96-rc2 review)

[Linus Torvalds]

On Fri, Feb 24, 2023 at 8:55 AM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Ok, it's not quilt's fault, it's GNU diff's fault from what I can tell.
> quilt relies on diff to generate the patch, and I can't figure out how
> to get diff to notice file permissions at all.  Am I just missing
> an option to 'diff' somewhere that I can't find in the manual?

No, I think you're right.

GNU patch was updated long ago to understand and apply the extended
git patch data.

But as far as I can tell, GNU diffutils have never actually grown the
ability to generate those extensions, even though at least the mode
bit one should be fairly simple (the file rename/copy ones are rather
more complicated, but those are just a "make diffs more legible and
compact" convenience thing, unlike the executable bit thing that
allows for scripts to remain executable).

> Anyway, quilt can handle replacing what it uses for 'diff', so I'll just
> replace it with 'git diff' and that seems to solve the problem for me!

That does sound like the right solution.

I don't think the diffutils people really care, but let's cc Paul
Eggert and Jim Meyering anyway, just in case. Because looking at the
diffutils git tree, it's still actively maintained even if the patch
load seems quite low.

Maybe there's some patch floating around that would allow diffutils to
also add those mode change lines. A quick google didn't find anything,
but Paul and Jim would probably know (or can just say "yeah, not even
interested").

                Linus