Re: [9front] patch(1) filename detection

[unobe@cpan.org]

Quoth Michael Forney <mforney@mforney.org>:
> However, longer term it might be worth supporting the
> git-diff extended header lines:
> 
> 	deleted file mode <mode>
> 	new file mode <mode>
> 	old mode <mode>
> 	new mode <mode>
> 
> There are also headers for renames and copies, but I don't think git
> or patch should bother with that, and should just present them as
> deleted and added files.
> 
> Thoughts?

There's also:
	similarity index <number>
	dissimilarity index <number>

Would one (or both) of those be useful if we're now talking about
modes, too?  Also, looking at the latest docs, I wasn't clear on what
the difference between 'deleted file mode', 'new file mode', 'old
mode', and 'new mode'.  For a patch, what's the purpose of all four of
them?  If a file is deleted, why isn't 'old mode' just used, and when
a file created, why isn't 'new mode' used?

The latest git docs also talk about combined diff mode, and it being
the default format with git-diff and git-show:

	index <hash>,<hash>..<hash>
	mode <mode>,<mode>..<mode>
	new file mode <mode>
	deleted file mode <mode>

That's not desired, right?

Reference: https://git-scm.com/docs/diff-format/2.37.2