https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71660
--- Comment #16 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Thiago Macieira from comment #14) > It was trying to guard against exactly what you said above: that the > alignment of a QAtomicInteger<T> was exactly the same as the alignment of a > plain T inside a struct, so one could replace a previous plain member with > an atomic and keep binary compatibility. That is not expected to work. > But it's clear now that atomic types may need extra alignment than the plain > types. In hindsight, the check is unnecessary and should be removed; people > should not expect to replace T with std::atomic<T> or QAtomicInteger<T> and > keep ABI. Agreed. But what we do care about is comment 2, i.e. _Atomic(T) and std::atomic<T> should have the same alignment (both in an out of structs). Maybe that needs the C front-end to change how _Atomic works, or maybe it needs the C++ library to change how std::atomic works, but I want to keep this bug open while comment 2 gives different answers for C and C++.
