https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101751
Florian Weimer <fw at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |fw at gcc dot gnu.org
--- Comment #1 from Florian Weimer <fw at gcc dot gnu.org> ---
Martin and I discussed this before. I believe the use of attribute access with
pthread_setspecific is quite wrong because it does not dereference the pointer
at all.
Consider this example:
#include <pthread.h>
#include <sys/mman.h>
void
f (pthread_key_t key)
{
pthread_setspecific (key, MAP_FAILED);
}
There is no way POSIX would consider this code invalid, but yet we warn:
t.c: In function ‘f’:
t.c:7:3: warning: ‘pthread_setspecific’ expecting 1 byte in a region of size 0
[-Wstringop-overread]
7 | pthread_setspecific (key, MAP_FAILED);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from t.c:1:
/usr/include/pthread.h:1308:12: note: in a call to function
‘pthread_setspecific’ declared with attribute ‘access (none, 2)’
1308 | extern int pthread_setspecific (pthread_key_t __key,
| ^~~~~~~~~~~~~~~~~~~
Removing attribute access is not a solution because the warning is implied by
the const void * argument type already. Access type none is merely declaration
that the pointed-to memory need not be initialized, it still needs to be a
valid address.
So yes, I consider this a GCC diagnostics bug: not for access type none, but
the fact that the diagnostic cannot be disabled at all for functions like
pthread_setspecific.
