* bug#8290: possibly-uninitialized variables in find_automatic_composition
@ 2011-03-19 2:12 Paul Eggert
2011-05-19 1:32 ` bug#8697: " handa
0 siblings, 1 reply; 2+ messages in thread
From: Paul Eggert @ 2011-03-19 2:12 UTC (permalink / raw)
To: 8290
Severity: minor
In the Emacs trunk, src/composite.c's find_automatic_composition has
two local variables 'check' and 'prev' that gcc -Wuninitialized warns
as being possibly being uninitialized when used. This function has
multiple gotos and dependencies on data structures that I don't
understand, so it's not clear to me that GCC is wrong here. So I'm
filing a bug report in the hopes that someone more expert can look at it.
I plan to work around the diagnostic by committing the following
change, which adds a FIXME comment asking for initial value if needed,
and for the comment to be removed if the code is OK as-is. IF_LINT
is used to tell GCC not to issue a warning here, for now.
I'm CC:ing this to Kenichi Handa, who committed the code in question,
to give him a heads-up about the problem.
* composite.c (find_automatic_composition): Mark vars as initialized, with a FIXME.
=== modified file 'src/composite.c'
--- src/composite.c 2011-03-19 00:58:10 +0000
+++ src/composite.c 2011-03-19 01:02:12 +0000
@@ -1489,7 +1489,13 @@
EMACS_INT head, tail, stop;
/* Limit to check a composition after POS. */
EMACS_INT fore_check_limit;
- struct position_record orig, cur, check, prev;
+ struct position_record orig, cur;
+
+ /* FIXME: It's not obvious whether these two variables need initialization.
+ If they do, please supply initial values.
+ If not, please remove this comment. */
+ struct position_record check IF_LINT (= {0}), prev IF_LINT (= {0});
+
Lisp_Object check_val, val, elt;
int c;
Lisp_Object window;
^ permalink raw reply [flat|nested] 2+ messages in thread
* bug#8697: possibly-uninitialized variables in find_automatic_composition
2011-03-19 2:12 bug#8290: possibly-uninitialized variables in find_automatic_composition Paul Eggert
@ 2011-05-19 1:32 ` handa
0 siblings, 0 replies; 2+ messages in thread
From: handa @ 2011-05-19 1:32 UTC (permalink / raw)
To: Paul Eggert; +Cc: 8697
Very sorry for the late response on this matter.
In article <4D841112.50403@cs.ucla.edu>, Paul Eggert <eggert@cs.ucla.edu> writes:
> In the Emacs trunk, src/composite.c's find_automatic_composition has
> two local variables 'check' and 'prev' that gcc -Wuninitialized warns
> as being possibly being uninitialized when used. This function has
> multiple gotos and dependencies on data structures that I don't
> understand, so it's not clear to me that GCC is wrong here. So I'm
> filing a bug report in the hopes that someone more expert can look at it.
> I plan to work around the diagnostic by committing the following
> change, which adds a FIXME comment asking for initial value if needed,
> and for the comment to be removed if the code is OK as-is. IF_LINT
> is used to tell GCC not to issue a warning here, for now.
> I'm CC:ing this to Kenichi Handa, who committed the code in question,
> to give him a heads-up about the problem.
Actually, those local variables are surely initialized when
used. But as they are initialized under a specific
condition (e.g. check_val is set to non-nil) and used under
the same condition, it's difficult for gcc to detect that.
Anyway, I've just committed an inproved version of
find_automatic_composition, and gcc won't complain about it
now.
2011-05-18 Kenichi Handa <handa@m17n.org>
* composite.c (CHAR_COMPOSABLE_P): Add more check for efficiency.
(BACKWARD_CHAR): Wrap the arg STOP by parenthesis.
(find_automatic_composition): Mostly rewrite for efficiency.
---
Kenichi Handa
handa@m17n.org
^ permalink raw reply [flat|nested] 2+ messages in thread
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2011-03-19 2:12 bug#8290: possibly-uninitialized variables in find_automatic_composition Paul Eggert
2011-05-19 1:32 ` bug#8697: " handa
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