bug#5751: Strange behaviour of ff-find-other-file

[Arne Schmitz <arne.schmitz@gmx.net>]

Hi everyone!

I have found a behaviour in ff-find-other-file that I would consider a
bug. However, I am not sure if this is definitely the case, but at
least I would say that the function's behaviour does not correspond to
it's implementation. The documentation says:

"Find the header or source file corresponding to this file."

Consider the following: the header and source for a certain case are
already being visited. Let's say the source is in
$CWD/project-src/foo.c, and the header in $CWD/include/foo.h. If
either ../project-src or ../include is not in the
ff-search-directories, the appropriate switch to the source or header
file will fail. Consider that this will also fail, if the
corresponding file is already being visited! This is not explicitly
demanded by the documentation, but would be useful behaviour in my
opinion. Looking at the source for ff-find-other-file leads to these
lines in the function ff-get-file-name:

  (if (bufferp (get-file-buffer filename))
      (setq found (buffer-file-name (get-file-buffer filename))))

To my understanding this is supposed to search through the current
buffers for the corresponding file. However, this seems to always
fail, since the variable filename is not expanded, as get-file-buffer
demands, and neither do I see how this is supposed to happen
anyway. So in the least, this code is useless, or worst, broken. Since
I like to have Emacs find the file, if there is a buffer visiting a
file with the correct name (although it might not be unique), I
changed the above lines to the following:

  (let ((b (find-if (lambda(x) (string= (buffer-name x) filename)) (buffer-list))))
    (if b
        (setq found (buffer-file-name b))))

Not sure, if this is the best code to achieve this, since I don't know
Emacs-Lisp very well, and a friend helped me figure this out.

Hope this helps and best regards,

Arne

In GNU Emacs 22.3.1 (i386-apple-darwin9.8.0, Carbon Version 1.6.0)
of 2010-01-10 on gs674-seijiz.local
Windowing system distributor `Apple Inc.', version 10.6.2
configured using `configure  '--prefix=/Applications/Emacs.app/Contents/Resources' '--with-carbon' '--without-x' '--libexecdir=/Volumes/Emacs/Emacs.app/Contents/MacOS/libexec' 'CC=gcc-4.2' 'CFLAGS=-O2 -arch i386 -arch ppc7400 -DUSE_ATSUI -DUSE_MAC_TSM''

Important settings:
 value of $LC_ALL: nil
 value of $LC_COLLATE: nil
 value of $LC_CTYPE: nil
 value of $LC_MESSAGES: nil
 value of $LC_MONETARY: nil
 value of $LC_NUMERIC: nil
 value of $LC_TIME: nil
 value of $LANG: nil
 locale-coding-system: iso-latin-1
 default-enable-multibyte-characters: t

Major mode: Help

Minor modes in effect:
 show-paren-mode: t
 server-mode: t
 desktop-save-mode: t
 ecb-minor-mode: t
 tabbar-mwheel-mode: t
 tabbar-mode: t
 which-function-mode: t
 mac-print-mode: t
 tooltip-mode: t
 tool-bar-mode: t
 mouse-wheel-mode: t
 menu-bar-mode: t
 file-name-shadow-mode: t
 global-font-lock-mode: t
 font-lock-mode: t
 blink-cursor-mode: t
 unify-8859-on-encoding-mode: t
 utf-translate-cjk-mode: t
 auto-compression-mode: t
 temp-buffer-resize-mode: t
 column-number-mode: t
 line-number-mode: t
 transient-mark-mode: t
 view-mode: t

Recent input:
<help-echo> <help-echo> <down-mouse-1> <drag-mouse-1> 
<down-mouse-1> <mouse-1> C-x C-f C-a C-k / . e m <tab> 
. d <tab> i n i <tab> <return> <wheel-down> <double-wheel-down> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <triple-wheel-up> <triple-wheel-up> 
<triple-wheel-up> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down> 
<triple-wheel-down> <wheel-down> <double-wheel-down> 
<triple-wheel-down> <down-mouse-1> <mouse-1> C-a C-SPC 
<down> <down> <down> <down> <up> <down> <down> <down> 
M-w C-h f f i n d - o <tab> <tab> <tab> <backspace> 
C-a C-k d <backspace> f f - f i <tab> o <tab> <return> 
C-x o C-x 1 <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<next> <prior> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<up> <up> <up> <up> <up> <up> <up> <up> <up> <up> <up> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <up> <up> 
<up> <up> <up> <up> <up> <up> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <up> <up> <up> <up> <up> <up> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <right> <left> <right> 
<right> M-x r e p o r <tab> <return>

Recent messages:
Showing all blocks ... done [3 times]
Showing all blocks ... done [2 times]
Loading semantic-tag-write...done
Mark saved where search started
Mark set
Type C-x 4 C-o RET to restore the other window.  
Loading eieio-opt...done
call-interactively: End of buffer [2 times]
Loading emacsbug...done
Loading dabbrev...done

-- 
Dipl.-Inform. Arne Schmitz              Phone   +49 (0)241 80-21817
Computer Graphics Group                 Mobile  +49 (0)151 29145947
RWTH Aachen University                  Fax     +49 (0)241 80-22899
Ahornstrasse 55, 52074 Aachen, Germany  http://www.rwth-graphics.de