[darcs-devel] [issue559] darcs diff shows misleading and/or nonsensical output on a patch that has conflicted

[Zooko]

New submission from Zooko <zooko at zooko.com>:

In the following transcript, I expect the "darcs diff" at the end to  
show that the line added by patch "b2" was "WHAA", not "WHOO".

I just ran afoul of this issue in practice, and it took me a little  
while to realize that darcs was sending me on a wild goose chase when  
it told me (by the output of "darcs diff") that a certain patch had  
made a certain change, when in truth that change was made by a  
different patch with which this patch conflicts.

Oh wait -- just now in reviewing this bug report before sending it,  
I've realized that darcs diff says that patch b2 *subtracted* line  
"WHOO", not that it added line "WHOO".  This is better!  It is  
nonsensical and confusing, which is better than plausible but wrong.   
However, it would be even better if "darcs diff" said that patch "b2"  
simply added line "WHAA".

Regards,

Zooko

wonwin-mcbrootles-computer:~/darcsbug$ mkdir i
wonwin-mcbrootles-computer:~/darcsbug$ cd i
wonwin-mcbrootles-computer:~/darcsbug/i$ darcs init
wonwin-mcbrootles-computer:~/darcsbug/i$ cat > f
WHEE
wonwin-mcbrootles-computer:~/darcsbug/i$ darcs add f ; darcs record -- 
all --author=a -m"init f"
Finished recording patch 'init f'
wonwin-mcbrootles-computer:~/darcsbug/i$ cd ..
wonwin-mcbrootles-computer:~/darcsbug$ darcs get i b1
Copying patch 1 of 1... done.
Finished getting.
wonwin-mcbrootles-computer:~/darcsbug$ darcs get i b2
Copying patch 1 of 1... done.
Finished getting.
wonwin-mcbrootles-computer:~/darcsbug$ cd b1
wonwin-mcbrootles-computer:~/darcsbug/b1$ cat >> f
WHOO
wonwin-mcbrootles-computer:~/darcsbug/b1$ darcs record --all -- 
author=a -m"b1 f"
Finished recording patch 'b1 f'
wonwin-mcbrootles-computer:~/darcsbug/b1$ cd ../b2/
wonwin-mcbrootles-computer:~/darcsbug/b2$ cat >> f
WHAA
wonwin-mcbrootles-computer:~/darcsbug/b2$ darcs record --all -- 
author=a -m"b2 f"
Finished recording patch 'b2 f'
wonwin-mcbrootles-computer:~/darcsbug/b2$ cd ..
wonwin-mcbrootles-computer:~/darcsbug$ darcs get b1 m
Copying patch 2 of 2... done.
Finished getting.
wonwin-mcbrootles-computer:~/darcsbug$ cd m
wonwin-mcbrootles-computer:~/darcsbug/m$ time darcs pull -a ../b2
We have conflicts in the following files:
./f
Finished pulling and applying.

real    0m1.057s
user    0m0.010s
sys     0m0.030s
wonwin-mcbrootles-computer:~/darcsbug/m$ darcs diff -u -p"b2 f"
Thu Nov  1 09:37:36 MDT 2007  a
   * b2 f
diff -rN -u old-m/f new-m/f
--- old-m/f     2007-11-01 09:39:55.000000000 -0600
+++ new-m/f     2007-11-01 09:39:55.000000000 -0600
@@ -1,2 +1 @@
WHEE
-WHOO

wonwin-mcbrootles-computer:~/darcsbug/m$ darcs diff -u -p"b1 f"
Thu Nov  1 09:37:27 MDT 2007  a
   * b1 f
diff -rN -u old-m/f new-m/f
--- old-m/f     2007-11-01 09:40:06.000000000 -0600
+++ new-m/f     2007-11-01 09:40:06.000000000 -0600
@@ -1 +1,2 @@
WHEE
+WHOO

----------
messages: 2228
nosy: beschmi, droundy, kowey, tommy, zooko
status: unread
title: darcs diff shows misleading and/or nonsensical output on a patch that has conflicted

__________________________________
Darcs bug tracker <bugs at darcs.net>
<http://bugs.darcs.net/issue559>
__________________________________