Bug#350076: subversion: svn diff --diff-cmd option fails inscrutably

[Britton Leo Kerin]

Package: subversion
Version: 1.2.3dfsg1-3
Severity: minor


This works: 

     svn diff --diff-cmd=diff sleep_on_option.c  | less

but this (using fldiff) doesn't:

     svn diff --diff-cmd=fldiff sleep_on_option.c  | less
                         ^^

I see some output in the terminal like this:

diff: option requires an argument -- L
diff: Try `diff --help' for more information.
Index: sleep_on_option.c
===================================================================

and fldiff dialog pops up saying 
 
    'Unable to optn "-L": No such file or directory'

Now since fldiff can be invoked 'fldiff file1 file2' just like diff,
you would expect it to work here, or if not, you would expect a
specification somewhere from svn saying just how it intends to invoke
the supplied diff command.  But I didn't find anything like that.
Alternately, svn diff could provide some way to output what exactly
its doing at run time.

The -L option to GNU diff does this:

`-L LABEL'
`--label=LABEL'
     Use LABEL instead of the file name in the context format (*note
     Context Format::) and unified format (*note Unified Format::)
     headers.

But its not worth trying to use this option (at least when --diff-cmd
is specified) if its going to break other diff programs.

It looks like fldiff is itself subversion aware, so you can just do
fldiff file.c in your working copy, but I don't think this has
anything to do with the above trouble, since fldiff still works fine
when invoked on two different files in a subversion repository.

-- System Information:
Debian Release: testing/unstable
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: i386 (i686)
Shell:  /bin/sh linked to /bin/bash
Kernel: Linux 2.6.12-1-k7
Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)

Versions of packages subversion depends on:
ii  db4.3-util                 4.3.29-3      Berkeley v4.3 Database Utilities
ii  libapr0                    2.0.55-4      the Apache Portable Runtime
ii  libc6                      2.3.5-8       GNU C Library: Shared libraries an
ii  libneon24                  0.24.7.dfsg-3 An HTTP and WebDAV client library
ii  libsvn0                    1.2.3dfsg1-3  shared libraries used by Subversio
ii  patch                      2.5.9-2       Apply a diff file to an original

subversion recommends no packages.

-- no debconf information