https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89464
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Andrew Pinski from comment #4) > The problem is in https://github.com/Silicondust/libhdhomerun: > hdhomerun_os_posix.h > Which does: > #if !defined(alignas) > #define alignas(n) __attribute__((aligned(n))) > #endif This would be less broken as: #if !defined(__cplusplus) && !defined(alignas) #define alignas(n) __attribute__((aligned(n))) #endif