[libcxx][iterator][ranges] adds `bidirectional_iterator` and `bidirectional_range`

Implements parts of:
    * P0896R4 The One Ranges Proposal`

Depends on D100275.

Differential Revision: https://reviews.llvm.org/D100278

2 files changed, 4 insertions, 4 deletions

diff --git a/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
index 4605cfd4a1bc..7fd0eff2b664 100644
--- a/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/range_concept_conformance.compile.pass.cpp
@@ -21,8 +21,8 @@ namespace stdr = std::ranges;
 
 static_assert(std::same_as<stdr::iterator_t<std::string>, std::string::iterator>);
 static_assert(stdr::common_range<std::string>);
-static_assert(stdr::forward_range<std::string>);
+static_assert(stdr::bidirectional_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::forward_range<std::string const>);
+static_assert(stdr::bidirectional_range<std::string const>);
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp
index 2777b1fec0c9..5aa1b60bdc4d 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/iterator_concept_conformance.compile.pass.cpp
@@ -22,7 +22,7 @@ using reverse_iterator = std::string::reverse_iterator;
 using const_reverse_iterator = std::string::const_reverse_iterator;
 using value_type = char;
 
-static_assert(std::forward_iterator<iterator>);
+static_assert(std::bidirectional_iterator<iterator>);
 static_assert(std::indirectly_writable<iterator, value_type>);
 static_assert(std::sentinel_for<iterator, iterator>);
 static_assert(std::sentinel_for<iterator, const_iterator>);
@@ -33,7 +33,7 @@ static_assert(std::sized_sentinel_for<iterator, const_iterator>);
 static_assert(!std::sized_sentinel_for<iterator, reverse_iterator>);
 static_assert(!std::sized_sentinel_for<iterator, const_reverse_iterator>);
 
-static_assert(std::forward_iterator<const_iterator>);
+static_assert(std::bidirectional_iterator<const_iterator>);
 static_assert(!std::indirectly_writable<const_iterator, value_type>);
 static_assert(std::sentinel_for<const_iterator, iterator>);
 static_assert(std::sentinel_for<const_iterator, const_iterator>);