Re: [PATCH] xdiff: print post-image for common records instead of pre-image

René Scharfe [off-list ref] writes:

Normally it doesn't matter if we show the pre-image or th post-image
for the common parts of a diff because they are the same.  If
white-space changes are ignored they can differ, though.  The
new text after applying the diff is more interesting in that case,
so show that instead of the old contents.

Note: GNU diff shows the pre-image.

Suggested-by: Junio C Hamano <redacted>
Signed-off-by: Rene Scharfe <redacted>

I was looking at this one again, and I think one possible downside of
showing post-image for the context lines is that the resulting patch would
not apply to the pre-image tree anymore. Probably GNU folks thought that
it is a big enough issue. Or perhaps they didn't simply care either way ;-)

In any case, showing pre-image lines as the context at least makes the
patch easier to apply, but the result would be different from the intended
post-image and would appear as if indentation fixes in the patch are
reverted, so you would need manual fix-up after applying such a patch
generated with (gnu) "diff -w".

I tried to generate an output from "show -w", with this change, on a
commit that is largely indentation fix. The resulting patch seems to apply
cleanly with "apply --ignore-space-change" to the parent of the commit
"show -w" was taken from; of course the result needs some manual fix-ups
for the indentation changes, but that is not a news anyway.  So I suspect
it won't be a huge downside and I think the benefit of being able to see
the post-image in the context when the user is more interested in how the
file looks like after the change outweighs it.

Thanks again.