[libc++] implement std::flat_multimap

Author: Hui Xie

libcxx/docs/FeatureTestMacroTable.rst

@@ -330,6 +330,10 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_expected``                                     ``202211L``
     ---------------------------------------------------------- -----------------
+    ``__cpp_lib_flat_map``                                     ``202207L``
+    ---------------------------------------------------------- -----------------
+    ``__cpp_lib_flat_set``                                     *unimplemented*
+    ---------------------------------------------------------- -----------------
     ``__cpp_lib_format_ranges``                                ``202207L``
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_formatters``                                   *unimplemented*

libcxx/docs/Status/Cxx23Papers.csv

@@ -52,7 +52,7 @@
 "`P2443R1 <https://wg21.link/P2443R1>`__","``views::chunk_by``","2022-02 (Virtual)","|Complete|","18",""
 "","","","","",""
 "`P0009R18 <https://wg21.link/P0009R18>`__","mdspan: A Non-Owning Multidimensional Array Reference","2022-07 (Virtual)","|Complete|","18",""
-"`P0429R9 <https://wg21.link/P0429R9>`__","A Standard ``flat_map``","2022-07 (Virtual)","|In Progress|","",""
+"`P0429R9 <https://wg21.link/P0429R9>`__","A Standard ``flat_map``","2022-07 (Virtual)","|Complete|","",""
 "`P1169R4 <https://wg21.link/P1169R4>`__","``static operator()``","2022-07 (Virtual)","|Complete|","16",""
 "`P1222R4 <https://wg21.link/P1222R4>`__","A Standard ``flat_set``","2022-07 (Virtual)","","",""
 "`P1223R5 <https://wg21.link/P1223R5>`__","``ranges::find_last()``, ``ranges::find_last_if()``, and ``ranges::find_last_if_not()``","2022-07 (Virtual)","|Complete|","19",""

libcxx/include/CMakeLists.txt

@@ -361,8 +361,10 @@ set(files
   __filesystem/space_info.h
   __filesystem/u8path.h
   __flat_map/flat_map.h
+  __flat_map/flat_multimap.h
   __flat_map/key_value_iterator.h
   __flat_map/sorted_unique.h
+  __flat_map/sorted_equivalent.h
   __format/buffer.h
   __format/concepts.h
   __format/container_adaptor.h

libcxx/include/__flat_map/flat_map.h

@@ -1188,7 +1188,7 @@ template <ranges::input_range _Range,
           class _Allocator = allocator<byte>,
           class            = __enable_if_t<!__is_allocator<_Compare>::value && __is_allocator<_Allocator>::value>>
 flat_map(from_range_t, _Range&&, _Compare = _Compare(), _Allocator = _Allocator())
-    -> flat_map<
+    ->flat_map<
         __range_key_type<_Range>,
         __range_mapped_type<_Range>,
         _Compare,
@@ -1197,7 +1197,7 @@ flat_map(from_range_t, _Range&&, _Compare = _Compare(), _Allocator = _Allocator(
 
 template <ranges::input_range _Range, class _Allocator, class = __enable_if_t<__is_allocator<_Allocator>::value>>
 flat_map(from_range_t, _Range&&, _Allocator)
-    -> flat_map<
+    ->flat_map<
         __range_key_type<_Range>,
         __range_mapped_type<_Range>,
         less<__range_key_type<_Range>>,