PR libstdc++/83427
* include/bits/refwrap.h (_Maybe_unary_or_binary_function): Move here
from <bits/std_function.h>.
(_Mem_fn_traits_base, _Mem_fn_traits): Move here, from <functional>.
(_Weak_result_type_impl, _Reference_wrapper_base): Deduce noexcept
for function types. Remove partial specializations for member
functions.
(_Weak_result_type_impl): Remove unused partial specializations for
non-referenceable function types and for references to functions.
(_Weak_result_type_memfun, _Reference_wrapper_base_memfun): New
helpers to handle member functions via _Mem_fn_traits.
(_Weak_result_type, reference_wrapper): Derive from new helpers.
* include/bits/std_function.h (_Maybe_unary_or_binary_function): Move
to <bits/refwrap.h>.
* include/std/functional (_Pack, _AllConvertible, _NotSame): Remove.
(_Mem_fn_traits_base, _Mem_fn_traits): Move to <bits/refwrap.h>.
* testsuite/20_util/bind/83427.cc: New test.
* testsuite/20_util/bind/refqual.cc: Add noexcept to functions and
check for weak result types.
* testsuite/20_util/reference_wrapper/83427.cc: New test.
From-SVN: r255651
Jakub Jelinek