[libcxx][ranges] Implement ranges::borrowed_range.

Differential Revision: https://reviews.llvm.org/D102426

libcxx/include/__ranges/concepts.h

@@ -36,6 +36,10 @@ namespace ranges {
     ranges::end(__t);
   };
 
+  template<class _Range>
+  concept borrowed_range = range<_Range> &&
+    (is_lvalue_reference_v<_Range> || enable_borrowed_range<remove_cvref_t<_Range>>);
+
   // `iterator_t` defined in <__ranges/access.h>
 
   template <range _Rp>

libcxx/test/std/containers/associative/map/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(!stdr::random_access_range<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(!stdr::random_access_range<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/associative/multimap/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(!stdr::random_access_range<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(!stdr::random_access_range<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/associative/multiset/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(!stdr::random_access_range<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(!stdr::random_access_range<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/associative/set/range_concept_conformance.compile.pass.cpp

@@ -27,6 +27,7 @@ static_assert(stdr::common_range<range>);
 static_assert(stdr::input_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::bidirectional_range<range const>);
@@ -35,3 +36,4 @@ static_assert(stdr::common_range<range const>);
 static_assert(stdr::input_range<range>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/array/range_concept_conformance.compile.pass.cpp

@@ -25,9 +25,11 @@ static_assert(std::same_as<stdr::iterator_t<range>, range::iterator>);
 static_assert(stdr::common_range<range>);
 static_assert(stdr::random_access_range<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(!stdr::view<range const>);
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::random_access_range<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/deque/range_concept_conformance.compile.pass.cpp

@@ -25,9 +25,11 @@ static_assert(stdr::common_range<range>);
 static_assert(stdr::random_access_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::random_access_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/forwardlist/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::forward_range<range>);
 static_assert(!stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(!stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::forward_range<range const>);
 static_assert(!stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(!stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/list/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(!stdr::random_access_range<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(!stdr::random_access_range<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/vector.bool/range_concept_conformance.compile.pass.cpp

@@ -25,9 +25,11 @@ static_assert(stdr::common_range<range>);
 static_assert(stdr::random_access_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::random_access_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/sequences/vector/range_concept_conformance.compile.pass.cpp

@@ -25,9 +25,11 @@ static_assert(stdr::common_range<range>);
 static_assert(stdr::random_access_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::random_access_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/unord/unord.map/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::forward_range<range>);
 static_assert(!stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::forward_range<range const>);
 static_assert(!stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/unord/unord.multimap/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::forward_range<range>);
 static_assert(!stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::forward_range<range const>);
 static_assert(!stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/unord/unord.multiset/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::forward_range<range>);
 static_assert(!stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::forward_range<range const>);
 static_assert(!stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/unord/unord.set/range_concept_conformance.compile.pass.cpp

@@ -26,10 +26,12 @@ static_assert(stdr::forward_range<range>);
 static_assert(!stdr::bidirectional_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(!stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::const_iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::forward_range<range const>);
 static_assert(!stdr::bidirectional_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(!stdr::borrowed_range<range const>);

libcxx/test/std/containers/views/range_concept_conformance.compile.pass.cpp

@@ -25,9 +25,11 @@ static_assert(stdr::common_range<range>);
 static_assert(stdr::random_access_range<range>);
 static_assert(!stdr::view<range>);
 static_assert(stdr::sized_range<range>);
+static_assert(stdr::borrowed_range<range>);
 
 static_assert(std::same_as<stdr::iterator_t<range const>, range::iterator>);
 static_assert(stdr::common_range<range const>);
 static_assert(stdr::random_access_range<range const>);
 static_assert(!stdr::view<range const>);
 static_assert(stdr::sized_range<range const>);
+static_assert(stdr::borrowed_range<range const>);

libcxx/test/std/input.output/filesystems/class.directory_iterator/range_concept_conformance.compile.pass.cpp

@@ -25,21 +25,25 @@ static_assert(stdr::common_range<fs::directory_iterator>);
 static_assert(stdr::input_range<fs::directory_iterator>);
 static_assert(!stdr::view<fs::directory_iterator>);
 static_assert(!stdr::sized_range<fs::directory_iterator>);
+static_assert(!stdr::borrowed_range<fs::directory_iterator>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::directory_iterator const>, fs::directory_iterator>);
 static_assert(stdr::common_range<fs::directory_iterator const>);
 static_assert(stdr::input_range<fs::directory_iterator const>);
 static_assert(!stdr::view<fs::directory_iterator const>);
 static_assert(!stdr::sized_range<fs::directory_iterator const>);
+static_assert(!stdr::borrowed_range<fs::directory_iterator const>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::recursive_directory_iterator>, fs::recursive_directory_iterator>);
 static_assert(stdr::common_range<fs::recursive_directory_iterator>);
 static_assert(stdr::input_range<fs::recursive_directory_iterator>);
 static_assert(!stdr::view<fs::recursive_directory_iterator>);
 static_assert(!stdr::sized_range<fs::recursive_directory_iterator>);
+static_assert(!stdr::borrowed_range<fs::recursive_directory_iterator>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::recursive_directory_iterator const>, fs::recursive_directory_iterator>);
 static_assert(stdr::common_range<fs::recursive_directory_iterator const>);
 static_assert(stdr::input_range<fs::recursive_directory_iterator const>);
 static_assert(!stdr::view<fs::recursive_directory_iterator const>);
 static_assert(!stdr::sized_range<fs::recursive_directory_iterator const>);
+static_assert(!stdr::borrowed_range<fs::recursive_directory_iterator const>);

libcxx/test/std/input.output/filesystems/class.path/range_concept_conformance.compile.pass.cpp

@@ -25,10 +25,12 @@ static_assert(stdr::bidirectional_range<fs::path>);
 static_assert(!stdr::view<fs::path>);
 static_assert(!stdr::random_access_range<fs::path>);
 static_assert(!stdr::sized_range<fs::path>);
+static_assert(!stdr::borrowed_range<fs::path>);
 
 static_assert(std::same_as<stdr::iterator_t<fs::path const>, fs::path::const_iterator>);
 static_assert(stdr::common_range<fs::path const>);
 static_assert(stdr::bidirectional_range<fs::path const>);
 static_assert(!stdr::view<fs::path const>);
 static_assert(!stdr::random_access_range<fs::path const>);
 static_assert(!stdr::sized_range<fs::path const>);
+static_assert(!stdr::borrowed_range<fs::path const>);

libcxx/test/std/ranges/range.range/borrowed_range.compile.pass.cpp

@@ -0,0 +1,63 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// template<class T>
+// concept borrowed_range;
+
+#include <ranges>
+
+struct NotRange {
+  int begin() const;
+  int end() const;
+};
+
+struct Range {
+  int *begin();
+  int *end();
+};
+
+struct ConstRange {
+  int *begin() const;
+  int *end() const;
+};
+
+struct BorrowedRange {
+  int *begin() const;
+  int *end() const;
+};
+
+template<>
+inline constexpr bool std::ranges::enable_borrowed_range<BorrowedRange> = true;
+
+static_assert(!std::ranges::borrowed_range<NotRange>);
+static_assert(!std::ranges::borrowed_range<NotRange&>);
+static_assert(!std::ranges::borrowed_range<const NotRange>);
+static_assert(!std::ranges::borrowed_range<const NotRange&>);
+static_assert(!std::ranges::borrowed_range<NotRange&&>);
+
+static_assert(!std::ranges::borrowed_range<Range>);
+static_assert( std::ranges::borrowed_range<Range&>);
+static_assert(!std::ranges::borrowed_range<const Range>);
+static_assert(!std::ranges::borrowed_range<const Range&>);
+static_assert(!std::ranges::borrowed_range<Range&&>);
+
+static_assert(!std::ranges::borrowed_range<ConstRange>);
+static_assert( std::ranges::borrowed_range<ConstRange&>);
+static_assert(!std::ranges::borrowed_range<const ConstRange>);
+static_assert( std::ranges::borrowed_range<const ConstRange&>);
+static_assert(!std::ranges::borrowed_range<ConstRange&&>);
+
+static_assert( std::ranges::borrowed_range<BorrowedRange>);
+static_assert( std::ranges::borrowed_range<BorrowedRange&>);
+static_assert( std::ranges::borrowed_range<const BorrowedRange>);
+static_assert( std::ranges::borrowed_range<const BorrowedRange&>);
+static_assert( std::ranges::borrowed_range<BorrowedRange&&>);

libcxx/test/std/ranges/range.range/borrowed_range.subsumption.compile.pass.cpp

@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17
+// UNSUPPORTED: libcpp-no-concepts
+// UNSUPPORTED: gcc-10
+
+// template<class T>
+// concept borrowed_range;
+
+#include <ranges>
+
+template <std::ranges::range R>
+consteval bool check_subsumption() {
+  return false;
+}
+
+template <std::ranges::borrowed_range R>
+consteval bool check_subsumption() {
+  return true;
+}
+
+static_assert(check_subsumption<int (&)[8]>());

libcxx/test/std/re/re.results/range_concept_conformance.compile.pass.cpp

@@ -24,9 +24,11 @@ static_assert(stdr::common_range<std::cmatch>);
 static_assert(stdr::random_access_range<std::cmatch>);
 static_assert(!stdr::view<std::cmatch>);
 static_assert(stdr::sized_range<std::cmatch>);
+static_assert(!stdr::borrowed_range<std::cmatch>);
 
 static_assert(std::same_as<stdr::iterator_t<std::cmatch const>, std::cmatch::const_iterator>);
 static_assert(stdr::common_range<std::cmatch const>);
 static_assert(stdr::random_access_range<std::cmatch const>);
 static_assert(!stdr::view<std::cmatch const>);
 static_assert(stdr::sized_range<std::cmatch const>);
+static_assert(!stdr::borrowed_range<std::cmatch const>);

libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp

@@ -24,9 +24,11 @@ static_assert(stdr::common_range<std::string>);
 static_assert(stdr::random_access_range<std::string>);
 static_assert(!stdr::view<std::string>);
 static_assert(stdr::sized_range<std::string>);
+static_assert(!stdr::borrowed_range<std::string>);
 
 static_assert(std::same_as<stdr::iterator_t<std::string const>, std::string::const_iterator>);
 static_assert(stdr::common_range<std::string const>);
 static_assert(stdr::random_access_range<std::string const>);
 static_assert(!stdr::view<std::string const>);
 static_assert(stdr::sized_range<std::string const>);
+static_assert(!stdr::borrowed_range<std::string const>);

libcxx/test/std/strings/string.view/range_concept_conformance.compile.pass.cpp

@@ -24,9 +24,11 @@ static_assert(stdr::common_range<std::string_view>);
 static_assert(stdr::random_access_range<std::string_view>);
 static_assert(!stdr::view<std::string_view>);
 static_assert(stdr::sized_range<std::string_view>);
+static_assert(stdr::borrowed_range<std::string_view>);
 
 static_assert(std::same_as<stdr::iterator_t<std::string_view const>, std::string_view::const_iterator>);
 static_assert(stdr::common_range<std::string_view const>);
 static_assert(stdr::random_access_range<std::string_view const>);
 static_assert(!stdr::view<std::string_view const>); // FIXME: string_view needs to be patched so this is true
 static_assert(stdr::sized_range<std::string_view const>);
+static_assert(stdr::borrowed_range<std::string_view const>);