https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104719
--- Comment #15 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jonathan Wakely <r...@gcc.gnu.org>: https://gcc.gnu.org/g:ef8d5ac08b5e60f35c52087d88c0235c8ce6b65b commit r13-113-gef8d5ac08b5e60f35c52087d88c0235c8ce6b65b Author: Jonathan Wakely <jwak...@redhat.com> Date: Fri Mar 25 10:28:28 2022 +0000 libstdc++: Simplify std::array accessors [PR104719] This removes the __array_traits::_S_ref and __array_traits::_S_ptr accessors, which only exist to make the special case of std::array<T, 0> syntactically well-formed. By changing the empty type used as the std::array<T, 0>::_M_elems data member to support operator[] and conversion to a pointer, we can write code using the natural syntax. The indirection through _S_ref and _S_ptr is removed for the common case, and a function call is only used for the special case of zero-size arrays. The invalid member access for zero-sized arrays is changed to use __builtin_trap() instead of a null dereference. This guarantees a runtime error if it ever gets called, instead of undefined behaviour that is likely to get optimized out as unreachable. libstdc++-v3/ChangeLog: PR libstdc++/104719 * include/std/array (__array_traits::_S_ref): Remove. (__array_traits::_S_ptr): Remove. (__array_traits<T, 0>::_Type): Define operator[] and operator T* to provide an array-like API. (array::_AT_Type): Remove public typeef. (array::operator[], array::at, array::front, array::back): Use index operator to access _M_elems instead of _S_ref. (array::data): Use implicit conversion from _M_elems to pointer. (swap(array&, array&)): Use __enable_if_t helper. (get<I>): Use index operator to access _M_elems. * testsuite/23_containers/array/tuple_interface/get_neg.cc: Adjust dg-error line numbers.
