reproducible but very odd make-mode crash

reproducible but very odd make-mode crash

[Joshua Varner]

[-- Attachment #1: Type: text/plain, Size: 819 bytes --]

I found a file that would consitently cause the problem from my last
e-mail - same stack trace and everything. So, i updated to CVS Head
and verified the bug is still there. I then tried to strip that file
down to a minimal test case and had some very strange results. While
trying to take out anything internal to the company I started just
replacing names with the string "stuff" and discovered that the text
was mainly irrelevant, then someone suggested i change all the text to
x's so i did that and the looping continued. For some reason the loop
is more sensitive to the length of the text and whitespace changes
than to any of the actual characters in the file.

I've attached the two makefiles that cause this problem on my system. 
If they seem odd, that's because at this point they are.

Josh

[-- Attachment #2: test.mk --]
[-- Type: application/octet-stream, Size: 674 bytes --]

# $Header: SSTUFFSTUFSTUFFFSTUFFSTUFFSTFSTUFFSTFSTUFFSTFSTUFFFFFstuffstuffstuffstuffstuffstuffstu $

default: all

STUFF=../../..
include $(STUFF)/stuff

STUFF = \
	stuffstuffstuffstuffs \

#	stuff
#	stuff
#	stuff
#	stuff
#	stuffstuffstuffs \
#	stuffstuffstuffs \
## End PRGS

stuff-stuff:
	stuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuff
	stuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffs
	stuffstuffstuffstuffstuffstuffstuf
	stuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstu
	stuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffstuffs

[-- Attachment #3: test1.mk --]
[-- Type: application/octet-stream, Size: 674 bytes --]

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxxxxx

xxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxx

xxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxxx

x	xxxxx
x	xxxxx
x	xxxxx
x	xxxxx
x	xxxxxxxxxxxxxxxxxx
x	xxxxxxxxxxxxxxxxxx
xx xxxxxxxx

xxxxxxxxxxxx
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

[-- Attachment #4: Type: text/plain, Size: 142 bytes --]

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Re: reproducible but very odd make-mode crash

[Joshua Varner]

The following patch resolves the problem i was having (I could only
reproduce this on my machine at work with RH9.0, but it was consistent
on that machine). By restricting the regexp to the current line (sort
of) i was able to avoid whatever strange thing was causing the regexp
to loop infinitely. I tried to use string-match but received some out
of range errors, I don't know what caused those, but that may be
faster than the narrowing. I, however, didn't notice any speed issue.

Josh

P.S. I don't know if this counts as trivial or not, but if you need
papers from me just let me know what I should do.

emacs]$ cvs diff -u lisp/progmodes/make-mode.el
Index: lisp/progmodes/make-mode.el
===================================================================
RCS file: /cvsroot/emacs/emacs/lisp/progmodes/make-mode.el,v
retrieving revision 1.97
diff -u -r1.97 make-mode.el
--- lisp/progmodes/make-mode.el 21 May 2005 02:45:27 -0000      1.97
+++ lisp/progmodes/make-mode.el 25 May 2005 21:23:43 -0000
@@ -1687,8 +1687,10 @@
        (or (eq (char-after) ?=)
            (get-text-property (1- (point)) 'face)
            (when (save-excursion
-                   (beginning-of-line)
-                   (looking-at makefile-dependency-regex))
+                   (save-restriction
+                     (narrow-to-region pt (point))
+                     (beginning-of-line)
+                     (looking-at makefile-dependency-regex)))
              (end-of-line)
              (throw 'found (point)))))
       (goto-char pt))

Re: reproducible but very odd make-mode crash

[Stefan Monnier]

> -                   (beginning-of-line)
> -                   (looking-at makefile-dependency-regex))
> +                   (save-restriction
> +                     (narrow-to-region pt (point))
> +                     (beginning-of-line)
> +                     (looking-at makefile-dependency-regex)))

Maybe it's makefile-dependency-regex which should be fixed to behave better.


        Stefan