https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124121
--- Comment #7 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> --- I do not see how triviality of the types matters here, as indicated by constant evaluator, the expression used to create elements is UB is _M_elems is not within its-lifetime: new (_M_elems[2]) _Tp() We could always zero-out the array (would use memset), but again this will have no trivial runtime cost for the cases where capacity is large. I think we should avoid doing that if possible. Maybe we could completly remove the start_lifetime_as_array, and assume that compilers do not optimize around this UB. I think that should be true, as types like inplace_vector very popular in the wild, and precede inplace_vector.
