libstdc++-v3: Implement allocator-aware from_range_t constructors for unordered containers.

This patch implements part of LWG2713 covering the from_range
constructors, which makes std::ranges::to<std::unordered_set>(alloc)
well-formed. Likewise for rest of unordered containers.

As this consturctors were added to v15, this has no impact
on code that compiled with previous versions.

libstdc++-v3/ChangeLog:

	* include/bits/unordered_map.h
	(unordered_map(from_range_t, _Rg&&, const allocator_type&))
	(unordered_multimap(from_range_t, _Rg&&, const allocator_type&)):
	Define.
	* include/bits/unordered_set.h
	(unordered_set(from_range_t, _Rg&&, const allocator_type&))
	(unordered_multiset(from_range_t, _Rg&&, const allocator_type&)):
	Define.
	* testsuite/23_containers/unordered_map/cons/from_range.cc: New tests.
	New tests.
	* testsuite/23_containers/unordered_multimap/cons/from_range.cc:
	New tests.
	* testsuite/23_containers/unordered_multiset/cons/from_range.cc:
	New tests.
	* testsuite/23_containers/unordered_set/cons/from_range.cc: New tests.
	* testsuite/std/ranges/conv/1.cc: New tests.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/std/ranges/conv/1.cc b/libstdc++-v3/testsuite/std/ranges/conv/1.cc
index 231cb9d..2caa1b8 100644
--- a/libstdc++-v3/testsuite/std/ranges/conv/1.cc
+++ b/libstdc++-v3/testsuite/std/ranges/conv/1.cc
@@ -12,6 +12,7 @@
 #include <testsuite_hooks.h>
 #include <testsuite_allocator.h>
 #include <testsuite_iterators.h>
+#include <unordered_map>
 
 void
 test_p1206r7_examples()
@@ -478,6 +479,26 @@ test_pr119282()
   return true;
 }
 
+void
+test_lwg2713()
+{
+  using Alloc = __gnu_test::uneq_allocator<std::pair<const int, const char*>>;
+  const Alloc alloc(303);
+  const std::map<int, const char*> m{{1, "one"}, {2, "two"}, {3, "three"}};
+  namespace ranges = std::ranges;
+
+  // Call constructors with bucket count
+  auto m1 = m | ranges::to<std::unordered_map>(0, alloc);
+  VERIFY( m1.get_allocator() == alloc );
+  auto m2 = m | ranges::to<std::unordered_multimap>(0, alloc);
+  VERIFY( m2.get_allocator() == alloc );
+  // These call constructors added in lwg2713
+  auto m3 = m | ranges::to<std::unordered_map>(alloc);
+  VERIFY( m3.get_allocator() == alloc );
+  auto m4 = m | ranges::to<std::unordered_multimap>(alloc);
+  VERIFY( m4.get_allocator() == alloc );
+}
+
 int main()
 {
   test_p1206r7_examples();
@@ -487,6 +508,7 @@ int main()
   test_2_1_3();
   test_2_1_4();
   test_2_2();
+  test_lwg2713();
   test_lwg3984();
   test_nodiscard();
   test_constexpr();