set-auto-mode ignores interpreter if mode is unknown

set-auto-mode ignores interpreter if mode is unknown

[Klaus Zeitler]

Not sure if this is a bug or a feature. One of my colleagues looked at
one of my ksh scripts that contained a mode instruction for a mode
that was unknown in his emacs session. To his (and my) amazement the buffer
was in fundamental mode and not in sh-mode.

Here's an example. Paste the following 2 lines in a file (but filename
without an extension that is known to auto-mode-alist) and load it in
emacs. 

--- cut ---
#! /usr/bin/ksh
# -*- unknown -*-
--- cut ---

CVS emacs will set the mode to fundamental-mode, whereas emacs 21 will set
it to sh-mode.


I looked at the code of set-auto-mode and it could easily be changed so that
it would check the interpreter, if no valid mode instruction can be found.

*** /vol/freeware/cvs/emacs/head/emacs/lisp/files.el    Mon Dec 12 10:31:47 2005
--- /vol/freeware/cvs/emacs/head/emacs/lisp/files.el.~1.796.~   Thu Dec  8 08:38:06 2005
***************
*** 2098,2105 ****
              (setq done t)
              (or (set-auto-mode-0 mode keep-mode-if-same)
                  ;; continuing would call minor modes again, toggling them off
!                 (throw 'nop nil))))))
!     (unless done
        ;; If we didn't, look for an interpreter specified in the first line.
        ;; As a special case, allow for things like "#!/bin/env perl", which
        ;; finds the interpreter anywhere in $PATH.
--- 2098,2104 ----
              (setq done t)
              (or (set-auto-mode-0 mode keep-mode-if-same)
                  ;; continuing would call minor modes again, toggling them off
!                 (throw 'nop nil)))))
        ;; If we didn't, look for an interpreter specified in the first line.
        ;; As a special case, allow for things like "#!/bin/env perl", which
        ;; finds the interpreter anywhere in $PATH.

Klaus

-- 
 ------------------------------------------
|  Klaus Zeitler      Lucent Technologies  |
|  Email:             kzeitler@lucent.com  |
 ------------------------------------------
---
The chief cause of problems is solutions.