spec1.arity0 foo spec1.arity0 bar spec1.arity1 z spec1.arity1 zz spec1.plus_flags o spec1.plus_flags p spec1.defaults x spec1.defaults y sizeof 8 sizeof 3 b = 1 i = 42 b = 3.140000 b = foo .sizeof(flag_spec::_FlagSpecAndMore) = 32 alignof(flag_spec::_FlagSpecAndMore) = 8 sizeof(out) = 8 sizeof(flag_spec::_FlagSpec) = 40 alignof(flag_spec::_FlagSpec) = 8 sizeof(out2) = 8 . Total: 2 tests (757 ticks, 0.001 sec), 5 assertions Pass: 2, fail: 0, skip: 0.