bug#9021: 24.0.50; epatch - weird, confusing, huh?

[Tino Calancha]

"Drew Adams" <drew.adams@oracle.com> writes:

> emacs -Q
>  
> This is the first time I've tried to use `epatch'.
>  
> I have the file to patch (e.g. `toto.el') in one window,
> and the patch (as a file, e.g. `throw.patch') in another.
> Both files are in the same directory, which is also the current
> directory (`default-directory').
>  
> `M-x epatch' in the buffer of the file to be patched.
>  
> `y' to "Is the patch already in a buffer?"
> I entered the name of the buffer of the patch, `throw.patch'.
>  
> I entered the name of the file to patch, `toto.el', to the
> question "File to patch (directory, if multifile patch):".
>  
> I got this message:
>  
> Ediff has inferred that
>  c:/drews-lisp-20/replace.el
> is assumed to be the target for this patch.  However, this file does not 
> exist.
>  
> Please enter an alternative patch target ...
>  
> No idea what to do now.  Why does it "infer" a file named "replace.el",
> when I input the name of the file to be patched, which has a totally
> different name ("toto.el")?  Who said anything about "replace.el"?
>  
> Anyway, I again try to input the (same) name of the file to be patched:
> "toto.el".
>  
> I then see this:
>  
> Ediff Session Group Panel: Multifile Patch
>  
>
>      Type ? to show useful commands in this buffer
>  
>
> *** Directory A: #<buffer throw.patch>
>  
>  
>  
>         Size   Last modified           Name
>     ----------------------------------------------
>  
>     Session 1:
>        112454   Jul  7 2011 08:24:00   c:/drews-lisp-20/toto.el
>     Session 2:
>        112454   Jul  7 2011 08:24:00   c:/drews-lisp-20/toto.el
>  
>
> Huh?  What does all of that mean?  Why does it think I want a
> "Multifile Patch"?  Why does it (apparently) consider the patch buffer
> to be a directory?  Why does it list two Sessions?  What do I do now?
>  
> I hit `?' for more info...and I understand...nothing more (maybe less).
>  
> I tried the same thing in Emacs 23.3 and 22.3, with the same result.  I
> tried consulting the Ediff manual for `epatch', but it was no help here.
>  
> What am I missing?  I'll admit that I do not know what I'm doing, here,
> but at the very least it seems like the UI is confusing and the doc is
> not very helpful.
>  
> I have no idea where to begin, and all I'm trying to do is patch a
> single file with a single patch.
>  
> OK, so eventually I realized (by accidentally mousing over text) that
> I could click one of the two (why two? why identical?) "sessions".
> I tried that and it applied the patch - bingo.  What to do then was
> clear (I'm familiar with ediff).
>  
> Whether or not someone who understands `epatch' will consider any of
> this a product bug (e.g. why "replace.el"?), I hope you will think
> about it some more from a UI/user (esp. newbie) perspective.
>
> I suggest that the `epatch' UI, doc, and help are a mess, at least for
> an `epatch' newbie such as myself.  I hope that someone will improve
> this, and I'd appreciate any explanation wrt the behavior I see and the
> questions raised above.  I still have no clue what all of that is about.
> Thx.
>  
>
> In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
>  of 2011-06-27 on 3249CTO
> Windowing system distributor `Microsoft Corp.', version 5.1.2600
> configured using `configure --with-gcc (4.5) --no-opt --cflags
> -Ic:/build/include'
I cannot reproduce it using Emacs 24.5 (oldest version i use).
I've tried to reproduce your receipt as follows:

$ cat /tmp/toto.el
1 2 3
4 5

$ cat /tmp/throw.patch
--- toto.el     2017-03-11 17:12:04.854906250 +0900
+++ toto-new.el 2017-03-11 17:12:40.639650683 +0900
@@ -1,2 +1,2 @@
-1 2 3
+1 h 3
 4 5

M-: (dired "/tmp") RET
M-x epatch RET y throw.patch RET /tmp/toto.el RET

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
In GNU Emacs 24.5.1 (x86_64-pc-linux-gnu, GTK+ Version 3.22.7)
 of 2017-01-23 on trouble, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11901000
System Description:     Debian GNU/Linux 9.0 (stretch)