[comint.el] `comint-preoutput-filter-functions' should be buffer-local

[Jesper Harder]

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Hi!

The comments in `comint.el':

;; Buffer Local Variables:
;;============================================================================
;; Comint mode buffer local variables:
;;  [..]
;;  comint-get-old-input                function Hooks for specific
;;  comint-input-filter-functions       hook    process-in-a-buffer
;;  comint-output-filter-functions      hook    function modes.
;;  comint-preoutput-filter-functions   hook


suggest that `comint-preoutput-filter-functions' is buffer-local.  But
as far as I can see it isn't.  Shouldn't there be a 

   (make-variable-buffer-local 'comint-preoutput-filter-functions)

somewhere in `comint.el'?

Also, the description of `comint-preoutput-filter-functions' as a hook
is slightly misleading -- stuff like:

   (add-hook 'comint-preoutput-filter-functions 'foo t t)

doesn't work.  I.e. you get an error if the fourth argument, LOCAL, is
non-nil:

error in process filter: comint-output-filter: Symbol's function definition is 
void: t

-- 
Cheers,
Jesper Harder