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* [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros
@ 2021-12-29 23:38 carlosgalvezp at gmail dot com
2021-12-29 23:40 ` [Bug c++/103862] " carlosgalvezp at gmail dot com
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: carlosgalvezp at gmail dot com @ 2021-12-29 23:38 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103862
Bug ID: 103862
Summary: Regression: -Wold-style-cast warns about system macros
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: carlosgalvezp at gmail dot com
Target Milestone: ---
Hi,
I thought this problem was solved by reading this:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=12258
But I can still find it on GCC 11.1:
// include/third_party.h
#pragma once
#define MY_CAST(x) ((int)x)
// main.cpp
#include <third_party.h>
int main()
{
int x = MY_CAST(123);
return x;
}
# g++-11 -isystem include -Wold-style-cast main.cpp
In file included from main.cpp:1:
main.cpp: In function 'int main()':
main.cpp:5:21: warning: use of old-style cast to 'int' [-Wold-style-cast]
5 | int x = MY_CAST(123);
| ^~~
# g++-11 --version
g++-11 (Ubuntu 11.1.0-1ubuntu1~20.04) 11.1.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/103862] Regression: -Wold-style-cast warns about system macros
2021-12-29 23:38 [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros carlosgalvezp at gmail dot com
@ 2021-12-29 23:40 ` carlosgalvezp at gmail dot com
2021-12-29 23:47 ` pinskia at gcc dot gnu.org
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: carlosgalvezp at gmail dot com @ 2021-12-29 23:40 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103862
--- Comment #1 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
The problem exists also in GCC 9.4.0
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/103862] Regression: -Wold-style-cast warns about system macros
2021-12-29 23:38 [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros carlosgalvezp at gmail dot com
2021-12-29 23:40 ` [Bug c++/103862] " carlosgalvezp at gmail dot com
@ 2021-12-29 23:47 ` pinskia at gcc dot gnu.org
2021-12-29 23:51 ` carlosgalvezp at gmail dot com
2021-12-30 23:44 ` [Bug c++/103862] " colomar.6.4.3 at gmail dot com
3 siblings, 0 replies; 5+ messages in thread
From: pinskia at gcc dot gnu.org @ 2021-12-29 23:47 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103862
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |diagnostic
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Carlos Galvez from comment #0)
> Hi,
>
> I thought this problem was solved by reading this:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=12258
That is a different issue, there the expression is fully from the system header
while here the constant is from a non-system header.
It looks like the warning is being based on where the inner expression is from
rather than where the cast is located.
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/103862] Regression: -Wold-style-cast warns about system macros
2021-12-29 23:38 [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros carlosgalvezp at gmail dot com
2021-12-29 23:40 ` [Bug c++/103862] " carlosgalvezp at gmail dot com
2021-12-29 23:47 ` pinskia at gcc dot gnu.org
@ 2021-12-29 23:51 ` carlosgalvezp at gmail dot com
2021-12-30 23:44 ` [Bug c++/103862] " colomar.6.4.3 at gmail dot com
3 siblings, 0 replies; 5+ messages in thread
From: carlosgalvezp at gmail dot com @ 2021-12-29 23:51 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103862
--- Comment #3 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Interesting, thanks for the quick reply! In case it helps, if I include the
header as a regular header, I do get the "note" referring to the system header:
# g++-11 -I include -Wold-style-cast main.cpp
In file included from main.cpp:1:
main.cpp: In function 'int main()':
main.cpp:5:21: warning: use of old-style cast to 'int' [-Wold-style-cast]
5 | int x = MY_CAST(123);
| ^~~
include/third_party.h:3:26: note: in definition of macro 'MY_CAST'
3 | #define MY_CAST(x) ((int)x)
|
^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/103862] -Wold-style-cast warns about system macros
2021-12-29 23:38 [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros carlosgalvezp at gmail dot com
` (2 preceding siblings ...)
2021-12-29 23:51 ` carlosgalvezp at gmail dot com
@ 2021-12-30 23:44 ` colomar.6.4.3 at gmail dot com
3 siblings, 0 replies; 5+ messages in thread
From: colomar.6.4.3 at gmail dot com @ 2021-12-30 23:44 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103862
Alejandro Colomar <colomar.6.4.3 at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |colomar.6.4.3 at gmail dot com
--- Comment #4 from Alejandro Colomar <colomar.6.4.3 at gmail dot com> ---
Hi,
I tried GCC 12 from Debian experimental and I can still reproduce the bug:
$ g++-12 --version
g++-12 (Debian 12-20211217-1) 12.0.0 20211217 (experimental) [master
r12-6027-g774269aa4b9]
I found something weird: if you enclose the macro argument in parentheses, the
warning is silenced:
#define MY_CAST(x) ((int)(x))
P.S.: If system header macros can be warned if part of the expression comes
from user code, I'd really like see -Wsizeof-pointer-div reporting warnings.
See <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94746>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-12-30 23:44 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
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2021-12-29 23:38 [Bug c++/103862] New: Regression: -Wold-style-cast warns about system macros carlosgalvezp at gmail dot com
2021-12-29 23:40 ` [Bug c++/103862] " carlosgalvezp at gmail dot com
2021-12-29 23:47 ` pinskia at gcc dot gnu.org
2021-12-29 23:51 ` carlosgalvezp at gmail dot com
2021-12-30 23:44 ` [Bug c++/103862] " colomar.6.4.3 at gmail dot com
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