This introduces two new headers:
<bits/ranges_base.h> defines the minimal components needed
for using C++20 ranges (customization point objects such as
std::ranges::begin, concepts such as std::ranges::range, etc.)
<bits/ranges_util.h> includes <bits/ranges_base.h> and additionally
defines subrange, which is needed by <bits/ranges_algo.h>.
Most of the content of <bits/ranges_base.h> was previously defined in
<bits/range_access.h>, but a few pieces were only defined in <ranges>.
This meant the entire <ranges> header was needed in <algorithm> and
<memory>, even though they don't use all the range adaptors.
By moving the ranges components out of <bits/range_access.h> that file
is left defining just the contents of [iterator.range] i.e. std::begin,
std::end, std::size etc. and not C++20 ranges components.
For consistency with other C++20 ranges headers, <bits/range_cmp.h> is
renamed to <bits/ranges_cmp.h>.
libstdc++-v3/ChangeLog:
* include/Makefile.am: Add new headers and adjust for renamed
header.
* include/Makefile.in: Regenerate.
* include/bits/iterator_concepts.h: Adjust for renamed header.
* include/bits/range_access.h (ranges::*): Move to new
<bits/ranges_base.h> header.
* include/bits/ranges_algobase.h: Include new <bits/ranges_base.h>
header instead of <ranges>.
* include/bits/ranges_algo.h: Include new <bits/ranges_util.h>
header.
* include/bits/range_cmp.h: Moved to...
* include/bits/ranges_cmp.h: ...here.
* include/bits/ranges_base.h: New header.
* include/bits/ranges_util.h: New header.
* include/experimental/string_view: Include new
<bits/ranges_base.h> header.
* include/std/functional: Adjust for renamed header.
* include/std/ranges (ranges::view_base, ranges::enable_view)
(ranges::dangling, ranges::borrowed_iterator_t): Move to new
<bits/ranges_base.h> header.
(ranges::view_interface, ranges::subrange)
(ranges::borrowed_subrange_t): Move to new <bits/ranges_util.h>
header.
* include/std/span: Include new <bits/ranges_base.h> header.
* include/std/string_view: Likewise.
* testsuite/24_iterators/back_insert_iterator/pr93884.cc: Add
missing <ranges> header.
* testsuite/24_iterators/front_insert_iterator/pr93884.cc:
Likewise.
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