libstdc++: Replace use of std::min in ranges::uninitialized_xxx algos [PR101587]

Because ranges can have any signed integer-like type as difference_type,
it's not valid to use std::min(diff1, diff2). Instead of calling
std::min with an explicit template argument, this adds a new __mindist
helper that determines the common type and uses that with std::min.

libstdc++-v3/ChangeLog:

	PR libstdc++/101587
	* include/bits/ranges_uninitialized.h (__detail::__mindist):
	New function object.
	(ranges::uninitialized_copy, ranges::uninitialized_copy_n)
	(ranges::uninitialized_move, ranges::uninitialized_move_n): Use
	__mindist instead of std::min.
	* testsuite/20_util/specialized_algorithms/uninitialized_copy/constrained.cc:
	Check ranges with difference difference types.
	* testsuite/20_util/specialized_algorithms/uninitialized_move/constrained.cc:
	Likewise.

2 files changed, 26 insertions, 0 deletions

diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/constrained.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/constrained.cc
index e0589e3..af3b733 100644
--- a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/constrained.cc
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/constrained.cc
@@ -175,6 +175,17 @@ test03()
     }
 }
 
+void
+test_pr101587()
+{
+  short in[1];
+  __gnu_test::test_contiguous_range r(in); // difference_type is integer-like
+  long out[1];
+  std::span<long> o(out); // difference_type is ptrdiff_t
+  ranges::uninitialized_copy(r, o);
+  ranges::uninitialized_copy_n(ranges::begin(r), 0, o.begin(), o.end());
+}
+
 int
 main()
 {
@@ -188,4 +199,6 @@ main()
 
   test02<false>();
   test02<true>();
+
+  test_pr101587();
 }
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_move/constrained.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_move/constrained.cc
index 4c858e1..fe82d1f1 100644
--- a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_move/constrained.cc
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_move/constrained.cc
@@ -185,6 +185,17 @@ test03()
     }
 }
 
+void
+test_pr101587()
+{
+  short in[1];
+  __gnu_test::test_contiguous_range r(in); // difference_type is integer-like
+  long out[1];
+  std::span<long> o(out); // difference_type is ptrdiff_t
+  ranges::uninitialized_move(r, o);
+  ranges::uninitialized_move_n(ranges::begin(r), 0, o.begin(), o.end());
+}
+
 int
 main()
 {
@@ -198,4 +209,6 @@ main()
 
   test02<false>();
   test02<true>();
+
+  test_pr101587();
 }