libstdc++: Add nodiscard attribute for ranges algorithm [PR121476]

This patch adds the [[nodiscard]] attribute to the operator() of ranges
algorithm function objects if their std counterpart has it.

Furthermore, we [[nodiscard]] the operator() of the following ranges
algorithms that lack a std counterpart:
* find_last, find_last_if, find_last_if_not (to match other find
  algorithms)
* contains, contains_subrange (to match find/any_of and search)

Finally, [[nodiscard]] is added to std::min and std::max overloads
that accept std::initializer_list. This appears to be an oversight,
as std::minmax is already marked, and other min overloads are as well.
The same applies to corresponding operator() overloads of ranges::min and
ranges::max.

	PR libstdc++/121476

libstdc++-v3/ChangeLog:

	* include/bits/ranges_algo.h (__all_of_fn::operator()):
	(__any_of_fn::operator(), __none_of_fn::operator())
	(__find_first_of_fn::operator(), __count_fn::operator())
	(__find_end_fn::operator(), __remove_if_fn::operator())
	(__remove_fn::operator(), __unique_fn::operator())
	(__is_sorted_until_fn::operator(), __is_sorted_fn::operator())
	(__lower_bound_fn::operator(), __upper_bound_fn::operator())
	(__equal_range_fn::operator(), __binary_search_fn::operator())
	(__is_partitioned_fn::operator(), __partition_point_fn::operator())
	(__minmax_fn::operator(), __min_element_fn::operator())
	(__includes_fn::operator(), __max_fn::operator())
	(__lexicographical_compare_fn::operator(), __clamp__fn::operator())
	(__find_last_fn::operator(), __find_last_if_fn::operator())
	(__find_last_if_not_fn::operator()): Add [[nodiscard]] attribute.
	* include/bits/ranges_algobase.h (__equal_fn::operator()):
	Add [[nodiscard]] attribute.
	* include/bits/ranges_util.h (__find_fn::operator())
	(__find_if_fn::operator(), __find_if_not_fn::operator())
	(__mismatch_fn::operator(), __search_fn::operator())
	(__min_fn::operator(), __adjacent_find_fn::operator()):
	Add [[nodiscard]] attribute.
	* include/bits/stl_algo.h (std::min(initializer_list<T>))
	(std::min(initializer_list<T>, _Compare))
	(std::max(initializer_list<T>))
	(std::mmax(initializer_list<T>, _Compare)): Add _GLIBCXX_NODISCARD.
	* testsuite/25_algorithms/min/constrained.cc: Silence nodiscard
	warning.
	* testsuite/25_algorithms/max/constrained.cc: Likewise.
	* testsuite/25_algorithms/minmax/constrained.cc: Likewise.
	* testsuite/25_algorithms/minmax_element/constrained.cc: Likewise.

0 files changed, 0 insertions, 0 deletions