Subject: bug#27501: 24.5; hippie-expand-only-buffers not considered when buffer-local in 'try-expand-dabbrev-all-buffers

From: Tom <[email-masked]>
Date: Mon, 26 Jun 2017 13:11:42 +0200

When I set the following in a mode
(https://github.com/TLINDEN/config-general-mode):

   (setq-local hippie-expand-only-buffers '(config-general-mode))

and have a .c file with c-mode open, and a file with config-general
mode, then 'try-expand-dabbrev-all-buffers expands from the .c file
as well, which is not what I expected.

It turns out, that the function (and all other try-expand-* functions
as well!) loops over all buffers in a while loop with 'set-buffer,
which then uses variables local for that *current* buffer or the
global ones, but not buffer-local variables from the original buffer,
from where the function was invoked. Since 'hippie-expand-only-buffers
is nil globally and not configured locally in c-mode (in my case),
it uses dabbrevs found in that file and thus ignores my buffer-local
setting.

The attached patch fixes this behavior by working on copies of the
relevant variables. It fixes 'try-expand-dabbrev-all-buffers only,
since I am not sure if the patch would be required by the other try
functions as well.

best regards,
Tom

In GNU Emacs 24.5.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2015-06-15 on nubic
Windowing system distributor `The X.Org Foundation', version
11.0.11501000
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Memory information:
((conses 16 87889 34583)
 (symbols 48 18533 1)
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 (strings 32 18602 28208)
 (string-bytes 1 447810)
 (vectors 16 9991)
 (vector-slots 8 397326 31713)
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 (intervals 56 233 101)
 (buffers 960 12)
 (heap 1024 29194 3379))
)

*** hippie-exp.el	2017-06-26 12:50:18.923557011 +0200
--- hippie-exp-patched.el	2017-06-26 12:52:12.731563202 +0200
***************
*** 926,932 ****
  string).  It returns t if a new expansion is found, nil otherwise."
    (let ((expansion ())
  	(buf (current-buffer))
! 	(orig-case-fold-search case-fold-search))
      (if (not old)
  	(progn
  	  (he-init-string (he-dabbrev-beg) (point))
--- 926,934 ----
  string).  It returns t if a new expansion is found, nil otherwise."
    (let ((expansion ())
  	(buf (current-buffer))
! 	(orig-case-fold-search case-fold-search)
!     (heib hippie-expand-ignore-buffers)
!     (heob hippie-expand-only-buffers))
      (if (not old)
  	(progn
  	  (he-init-string (he-dabbrev-beg) (point))
***************
*** 941,949 ****
  			(< he-searched-n-bufs hippie-expand-max-buffers)))
  	  (set-buffer (car he-search-bufs))
  	  (if (and (not (eq (current-buffer) buf))
! 		   (if hippie-expand-only-buffers
! 		       (he-buffer-member hippie-expand-only-buffers)
! 		     (not (he-buffer-member hippie-expand-ignore-buffers))))
  	      (save-excursion
  		(save-restriction
  		  (if hippie-expand-no-restriction
--- 943,951 ----
  			(< he-searched-n-bufs hippie-expand-max-buffers)))
  	  (set-buffer (car he-search-bufs))
  	  (if (and (not (eq (current-buffer) buf))
! 		   (if heob
! 		       (he-buffer-member heob)
! 		     (not (he-buffer-member heib))))
  	      (save-excursion
  		(save-restriction
  		  (if hippie-expand-no-restriction