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* [Bug c/6906] warn about asserts with side effects
[not found] <20020601163600.6906.123468@bugs.debian.org>
@ 2003-12-31 17:20 ` pinskia at gcc dot gnu dot org
2004-08-10 23:56 ` mbp at sourcefrog dot net
1 sibling, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2003-12-31 17:20 UTC (permalink / raw)
To: gcc-bugs
--
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
Last reconfirmed|2003-10-01 04:02:16 |2003-12-31 16:03:17
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6906
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/6906] warn about asserts with side effects
[not found] <20020601163600.6906.123468@bugs.debian.org>
2003-12-31 17:20 ` [Bug c/6906] warn about asserts with side effects pinskia at gcc dot gnu dot org
@ 2004-08-10 23:56 ` mbp at sourcefrog dot net
1 sibling, 0 replies; 5+ messages in thread
From: mbp at sourcefrog dot net @ 2004-08-10 23:56 UTC (permalink / raw)
To: gcc-bugs
------- Additional Comments From mbp at sourcefrog dot net 2004-08-10 23:56 -------
It might be nice if there were a compile-time function similar to
__builtin_constant_p which checked whether an expression was free of
side-effects. One could then write
# define assert(expr) \
(__builtin_pure_p((expr)) ? _real_assert(expr) :
warning_assert_expr_not_pure())
So this would be true for things like
__builtin_pure_p(arry[0] == 0)
__builtin_pure_p(strlen(s) == 5)
assuming the functions had the right attributes.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6906
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/6906] warn about asserts with side effects
[not found] <bug-6906-4@http.gcc.gnu.org/bugzilla/>
@ 2020-04-16 17:43 ` felix.von.s at posteo dot de
0 siblings, 0 replies; 5+ messages in thread
From: felix.von.s at posteo dot de @ 2020-04-16 17:43 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=6906
felix <felix.von.s at posteo dot de> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |felix.von.s at posteo dot de
--- Comment #9 from felix <felix.von.s at posteo dot de> ---
I have just realised that __builtin_pure_p is already expressible:
#define __builtin_pure_p(expr) \
(__builtin_object_size(((void)(expr), ""), 2))
If (expr) is free of side effects, this is the same as
__builtin_object_size("", 2), which is 1. Otherwise, the expression returns 0.
This is documented behaviour, by the way. The documentation for
__builtin_object_size at
<https://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html> states:
> __builtin_object_size never evaluates its arguments for side effects.
> If there are any side effects in them, it returns (size_t) -1 for
> type 0 or 1 and (size_t) 0 for type 2 or 3.
Experimentation reveals __attribute__((pure)) is enough for
__builtin_object_size to consider a function free of side effects.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/6906] warn about asserts with side effects
[not found] <bug-6906-1490@http.gcc.gnu.org/bugzilla/>
2006-10-15 19:45 ` pinskia at gcc dot gnu dot org
@ 2008-03-03 2:56 ` chris dot pickett at mail dot mcgill dot ca
1 sibling, 0 replies; 5+ messages in thread
From: chris dot pickett at mail dot mcgill dot ca @ 2008-03-03 2:56 UTC (permalink / raw)
To: gcc-bugs
------- Comment #5 from chris dot pickett at mail dot mcgill dot ca 2008-03-03 02:55 -------
Maybe you could fix the preprocessor to warn about operators with known side
effects. Can cpp see the entire expr in assert (expr)? If so, just search the
tokens for =, ++, --, +=, -=, etc.
--
chris dot pickett at mail dot mcgill dot ca changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |chris dot pickett at mail
| |dot mcgill dot ca
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6906
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c/6906] warn about asserts with side effects
[not found] <bug-6906-1490@http.gcc.gnu.org/bugzilla/>
@ 2006-10-15 19:45 ` pinskia at gcc dot gnu dot org
2008-03-03 2:56 ` chris dot pickett at mail dot mcgill dot ca
1 sibling, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2006-10-15 19:45 UTC (permalink / raw)
To: gcc-bugs
------- Comment #4 from pinskia at gcc dot gnu dot org 2006-10-15 19:45 -------
*** Bug 29480 has been marked as a duplicate of this bug. ***
--
pinskia at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |robert at linuxfromscratch
| |dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=6906
^ permalink raw reply [flat|nested] 5+ messages in thread
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[not found] <20020601163600.6906.123468@bugs.debian.org>
2003-12-31 17:20 ` [Bug c/6906] warn about asserts with side effects pinskia at gcc dot gnu dot org
2004-08-10 23:56 ` mbp at sourcefrog dot net
[not found] <bug-6906-1490@http.gcc.gnu.org/bugzilla/>
2006-10-15 19:45 ` pinskia at gcc dot gnu dot org
2008-03-03 2:56 ` chris dot pickett at mail dot mcgill dot ca
[not found] <bug-6906-4@http.gcc.gnu.org/bugzilla/>
2020-04-16 17:43 ` felix.von.s at posteo dot de
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