Re: epatch for multifile patches

[Michael Heerdegen <michael_heerdegen@web.de>]

Arseny Sher <sher-ars@yandex.ru> writes:

> Hello,
>
> I am having trouble using epatch while applying multifile patches.
> Consider the following simple example:
>
> ars@ars-thinkpad ~/tmp $ mkdir -p old/src
> ars@ars-thinkpad ~/tmp $ echo "void main() { }" > old/src/hello.c
> ars@ars-thinkpad ~/tmp $ mkdir -p new/src
> ars@ars-thinkpad ~/tmp $ echo "int main() { return 0; }" >
> new/src/hello.c
> ars@ars-thinkpad ~/tmp $ diff -cr old/ new/ > tmp.patch
> ars@ars-thinkpad ~/tmp $ cat tmp.patch
> diff -cr old/src/hello.c new/src/hello.c
> *** old/src/hello.c	2017-03-08 14:29:24.743846995 +0300
> --- new/src/hello.c	2017-03-08 14:29:32.399846824 +0300
> ***************
> *** 1 ****
> ! void main() { }
> --- 1 ----
> ! int main() { return 0; }
>
>
> Now I start emacs and do M-x epatch. First of all, it asks me for
> patch buffer or file, I point to '~/tmp/tmp.patch'. Then it asks for
> directory to patch, I say '~/tmp/old' and ediff complains
>
> Ediff has inferred that
> 	/home/ars/tmp/old/hello.c
> is assumed to be the target for this patch.  However, this file does
> not exist.
>
> Please enter an alternative patch target ...
>
>
> because it ignores the path ('src' directory in this case) to the file.
> Ediff manual says: "Ediff can recognize multi-file patches only if they
> are in the context format or GNU unified format. All other patches are
> treated as 1-file patches. Ediff is [hopefully] using the same algorithm
> as patch to determine which files need to be patched." So, if I
> understood it correctly, this should work. Is it a bug or what?

I asked a similar question some time ago on emacs-dev.  My impression
was that nobody is actually really using this...

The behavior doesn't make sense, so it is a bug.  It should not be hard
to fix for someone knowing the code.  I stepped through the code with
edebug, everything is there, just the file paths are treated in a way
which is not correct in such cases.

If there is no related bug report yet, maybe you can create one (I
didn't)?


Thanks,

Michael.