https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108374
Bug ID: 108374 Summary: [12/13 Regression] unexpected -Wstringop-overflow when using std::atomic and std::shared_ptr Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: romain.geissler at amadeus dot com Target Milestone: --- Hi, The following snippet produces an unexpected -Wstringop-overflow with gcc 12 and current trunk: #include <atomic> #include <memory> struct A: public std::enable_shared_from_this<A> { std::atomic<size_t> _attr; }; void f(std::shared_ptr<A> pointer) { std::weak_ptr<A> weakPointer(pointer); [[maybe_unused]] const unsigned int aAttr = weakPointer.lock()->_attr; } Compiler Explorer output: In file included from /opt/compiler-explorer/gcc-trunk-20230111/include/c++/13.0.0/atomic:41, from <source>:1: In member function 'std::__atomic_base<_IntTp>::__int_type std::__atomic_base<_IntTp>::load(std::memory_order) const [with _ITp = long unsigned int]', inlined from 'std::__atomic_base<_IntTp>::operator __int_type() const [with _ITp = long unsigned int]' at /opt/compiler-explorer/gcc-trunk-20230111/include/c++/13.0.0/bits/atomic_base.h:365:20, inlined from 'void f(std::shared_ptr<A>)' at <source>:13:69: /opt/compiler-explorer/gcc-trunk-20230111/include/c++/13.0.0/bits/atomic_base.h:505:31: error: 'long unsigned int __atomic_load_8(const volatile void*, int)' writing 8 bytes into a region of size 0 overflows the destination [-Werror=stringop-overflow=] 505 | return __atomic_load_n(&_M_i, int(__m)); | ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~ In function 'void f(std::shared_ptr<A>)': cc1plus: note: destination object is likely at address zero cc1plus: some warnings being treated as errors Compiler returned: 1 I have found bug #104475 which seems to also deal with atomics and -Wstringop-overflow however I can't judge if it looks like a duplicate or a different issue. Cheers, Romain