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* [Bug c/105628] New: False positive with -Waddress
@ 2022-05-17 12:32 jochen447 at concept dot de
2022-05-17 12:44 ` [Bug c/105628] " pinskia at gcc dot gnu.org
` (5 more replies)
0 siblings, 6 replies; 7+ messages in thread
From: jochen447 at concept dot de @ 2022-05-17 12:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
Bug ID: 105628
Summary: False positive with -Waddress
Product: gcc
Version: 12.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: jochen447 at concept dot de
Target Milestone: ---
Created attachment 52986
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52986&action=edit
minified example program to show the false positive
Option -Wall also enables -Waddress, which causes a lot of false positives like
shown in my attached example problem (minimized and anonymized real world
example):
waddress.c: In function ‘comp_has_ExtraPtr’:
waddress.c:44:29: warning: the comparison will always evaluate as ‘true’ for
the pointer operand in ‘(struct Extra **)&comp->pin + 4’ must not be NULL
[-Waddress]
44 | return ExtraPtrOf(comp) ? 1 : 0;
| ^
It only seems to be emitted when using the ?-operator.
# gcc -v
...
gcc version 12.1.1 20220507 (Red Hat 12.1.1-1) (GCC)
# uname -a
Linux fedora 5.17.6-300.fc36.x86_64 #1 SMP PREEMPT Mon May 9 15:47:11 UTC 2022
x86_64 x86_64 x86_64 GNU/Linux
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
@ 2022-05-17 12:44 ` pinskia at gcc dot gnu.org
2022-10-25 7:11 ` [Bug c/105628] [12/13 Regression] " pinskia at gcc dot gnu.org
` (4 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-05-17 12:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The warning is correct but it should not be done.
Simpele testcase:
struct s{ int f; };
int g(struct s t){
return (t.f?&t.f : 0)? 1 : 0;
}
The problem is gcc did some optimizations before the warning and pushed the
implicit != 0 into each arm of the ?; operator
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] [12/13 Regression] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
2022-05-17 12:44 ` [Bug c/105628] " pinskia at gcc dot gnu.org
@ 2022-10-25 7:11 ` pinskia at gcc dot gnu.org
2023-04-08 14:45 ` law at gcc dot gnu.org
` (3 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2022-10-25 7:11 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Summary|False positive with |[12/13 Regression] False
|-Waddress |positive with -Waddress
Target Milestone|--- |12.3
Keywords| |needs-bisection
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] [12/13 Regression] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
2022-05-17 12:44 ` [Bug c/105628] " pinskia at gcc dot gnu.org
2022-10-25 7:11 ` [Bug c/105628] [12/13 Regression] " pinskia at gcc dot gnu.org
@ 2023-04-08 14:45 ` law at gcc dot gnu.org
2023-05-08 12:24 ` [Bug c/105628] [12/13/14 " rguenth at gcc dot gnu.org
` (2 subsequent siblings)
5 siblings, 0 replies; 7+ messages in thread
From: law at gcc dot gnu.org @ 2023-04-08 14:45 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
Jeffrey A. Law <law at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |law at gcc dot gnu.org
Priority|P3 |P2
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] [12/13/14 Regression] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
` (2 preceding siblings ...)
2023-04-08 14:45 ` law at gcc dot gnu.org
@ 2023-05-08 12:24 ` rguenth at gcc dot gnu.org
2024-03-11 12:32 ` pinskia at gcc dot gnu.org
2024-03-11 12:34 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: rguenth at gcc dot gnu.org @ 2023-05-08 12:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|12.3 |12.4
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 12.3 is being released, retargeting bugs to GCC 12.4.
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] [12/13/14 Regression] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
` (3 preceding siblings ...)
2023-05-08 12:24 ` [Bug c/105628] [12/13/14 " rguenth at gcc dot gnu.org
@ 2024-03-11 12:32 ` pinskia at gcc dot gnu.org
2024-03-11 12:34 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-03-11 12:32 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 114306 has been marked as a duplicate of this bug. ***
^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105628] [12/13/14 Regression] False positive with -Waddress
2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
` (4 preceding siblings ...)
2024-03-11 12:32 ` pinskia at gcc dot gnu.org
@ 2024-03-11 12:34 ` pinskia at gcc dot gnu.org
5 siblings, 0 replies; 7+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-03-11 12:34 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105628
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |DUPLICATE
Status|UNCONFIRMED |RESOLVED
--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So it turns out the change for ?: to warn for -Waddress was done on purpose.
See PR 102967 . PR 102967 is about the wrong location for the warning and
such but it was originally about the same type of expression.
*** This bug has been marked as a duplicate of bug 102967 ***
^ permalink raw reply [flat|nested] 7+ messages in thread
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2022-05-17 12:32 [Bug c/105628] New: False positive with -Waddress jochen447 at concept dot de
2022-05-17 12:44 ` [Bug c/105628] " pinskia at gcc dot gnu.org
2022-10-25 7:11 ` [Bug c/105628] [12/13 Regression] " pinskia at gcc dot gnu.org
2023-04-08 14:45 ` law at gcc dot gnu.org
2023-05-08 12:24 ` [Bug c/105628] [12/13/14 " rguenth at gcc dot gnu.org
2024-03-11 12:32 ` pinskia at gcc dot gnu.org
2024-03-11 12:34 ` pinskia at gcc dot gnu.org
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