https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88462
--- Comment #2 from ro at CeBiTec dot Uni-Bielefeld.DE <ro at CeBiTec dot Uni-Bielefeld.DE> --- > pragma(msg, pthread_mutex_t.alignof); > pragma(msg, Mutex.alignof); > pragma(msg, Mutex.m_hndl.offsetof); I get 8u 4u /homes/ro/mutex_align.d:6:13: error: class core.sync.mutex.Mutex member m_hndl is not accessible 16u The first is right, but Mutex alignment is off, probably leading to the 4-byte alignment of m_hndl I'm seeing.