https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107694
Bug ID: 107694
Summary: Bogus stringop-overflow warning in gcc 12
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: mh+gcc at glandium dot org
Target Milestone: ---
Reproducer:
```
#include <atomic>
class nsISupports {
public:
virtual int Release();
};
struct JSPrincipals {
std::atomic<int> refcount;
};
class nsJSPrincipals : nsISupports, JSPrincipals {
static nsJSPrincipals* get(JSPrincipals* principals) {
return static_cast<nsJSPrincipals*>(principals);
}
void Destroy(JSPrincipals* jsprin);
};
void nsJSPrincipals::Destroy(JSPrincipals* jsprin) {
nsJSPrincipals* nsjsprin = nsJSPrincipals::get(jsprin);
nsjsprin->refcount.fetch_add(1, std::memory_order_acq_rel);
nsjsprin->Release();
}
```
Compile with: g++ -c -O2 -Werror=stringop-overflow
It says:
```
In file included from /builds/worker/fetches/gcc/include/c++/12.2.0/atomic:41,
from Unified_cpp_caps0.ii.cpp:1:
In member function 'std::__atomic_base<_IntTp>::__int_type
std::__atomic_base<_IntTp>::fetch_add(__int_type, std::memory_order) [with _ITp
= int]',
inlined from 'void nsJSPrincipals::Destroy(JSPrincipals*)' at
Unified_cpp_caps0.ii.cpp:19:30:
/builds/worker/fetches/gcc/include/c++/12.2.0/bits/atomic_base.h:618:34: error:
'unsigned int __atomic_fetch_add_4(volatile void*, unsigned int, int)' writing
4 bytes into a region of size 0 overflows the destination
[-Werror=stringop-overflow=]
618 | { return __atomic_fetch_add(&_M_i, __i, int(__m)); }
| ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
cc1plus: some warnings being treated as errors
```
