The deduced return type causes the instantiation of the function body,
which can then require the instantiation of std::projected::operator*
which is intentionally not defined.
This patch uses a helper trait to define the return type, so that the
function body doesn't need to be instantiated. That helper trait can
then also be used in other places that currently check the return type
of ranges::iter_move (iter_rvalue_reference_t and indirectly_readable).
2020-05-01 Jonathan Wakely <jwakely@redhat.com>
Patrick Palka <ppalka@redhat.com>
PR libstdc++/92894
* include/bits/iterator_concepts.h (ranges::__cust_imove::_IMove):
Add trait to determine return type and an alias for it.
(ranges::__cust_imove::_IMove::operator()): Use __result instead of
deduced return type.
(iter_rvalue_reference_t): Use _IMove::__type instead of checking
the result of ranges::iter_move.
(__detail::__indirectly_readable_impl): Use iter_rvalue_reference_t
instead of checking the result of ranges::iter_move.
* testsuite/24_iterators/customization_points/92894.cc: New test.
* testsuite/24_iterators/indirect_callable/92894.cc: New test.
* include/bits/iterator_concepts.h (iter_difference_t, iter_value_t):
Use remove_cvref_t.
(readable_traits): Rename to indirectly_readable_traits.
(readable): Rename to indirectly_readable.
(writable): Rename to indirectly_writable.
(__detail::__iter_exchange_move): Do not use remove_reference_t.
(indirectly_swappable): Adjust requires expression parameter types.
expression.
* include/bits/ranges_algo.h (ranges::transform, ranges::replace)
(ranges::replace_if, ranges::generate_n, ranges::generate)
(ranges::remove): Use new name for writable.
* include/bits/stl_iterator.h (__detail::__common_iter_has_arrow):
Use new name for readable.
* include/ext/pointer.h (readable_traits<_Pointer_adapter<P>>): Use
new name for readable_traits.
* testsuite/24_iterators/associated_types/readable.traits.cc: Likewise.
* testsuite/24_iterators/indirect_callable/projected.cc: Adjust for
new definition of indirectly_readable.
The alias template wasn't working because it applied iter_reference_t to
the pack of iterators before and after passing the pack to the
__indeirect_result helper.
* include/bits/iterator_concepts.h (indirect_result_t): Do not apply
iter_reference_t to parameter pack.
* testsuite/24_iterators/indirect_callable/projected.cc: New test.
From-SVN: r279170
