[libc++][modules] Mark as implemented. (#90091)

The feature has been implemented in LLVM 18 as an experimental feature.
This marks the paper as complete and sets the feature-test macro.

Implements
- P2465R3 Standard Library Modules std and std.compat

Fixes: #89579

Author: mordante

libcxx/docs/FeatureTestMacroTable.rst

@@ -340,6 +340,8 @@ Status
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_mdspan``                                       ``202207L``
     ---------------------------------------------------------- -----------------
+    ``__cpp_lib_modules``                                      ``202207L``
+    ---------------------------------------------------------- -----------------
     ``__cpp_lib_move_only_function``                           *unimplemented*
     ---------------------------------------------------------- -----------------
     ``__cpp_lib_optional``                                     ``202110L``

libcxx/docs/Status/Cxx23Papers.csv

@@ -75,7 +75,7 @@
 "`P2445R1 <https://wg21.link/P2445R1>`__","LWG","``forward_like``","July 2022","|Complete|","16.0"
 "`P2446R2 <https://wg21.link/P2446R2>`__","LWG","``views::as_rvalue``","July 2022","|Complete|","16.0","|ranges|"
 "`P2460R2 <https://wg21.link/P2460R2>`__","LWG","Relax requirements on ``wchar_t`` to match existing practices","July 2022","",""
-"`P2465R3 <https://wg21.link/P2465R3>`__","LWG","Standard Library Modules ``std`` and ``std.compat``","July 2022","",""
+"`P2465R3 <https://wg21.link/P2465R3>`__","LWG","Standard Library Modules ``std`` and ``std.compat``","July 2022","|Complete|","19.0",""
 "`P2467R1 <https://wg21.link/P2467R1>`__","LWG","Support exclusive mode for ``fstreams``","July 2022","|Complete|","18.0",""
 "`P2474R2 <https://wg21.link/P2474R2>`__","LWG","``views::repeat``","July 2022","|Complete|","17.0","|ranges|"
 "`P2494R2 <https://wg21.link/P2494R2>`__","LWG","Relaxing range adaptors to allow for move only types","July 2022","|Complete|","17.0","|ranges|"

libcxx/include/version

@@ -465,6 +465,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # define __cpp_lib_ios_noreplace                        202207L
 # define __cpp_lib_is_scoped_enum                       202011L
 # define __cpp_lib_mdspan                               202207L
+# define __cpp_lib_modules                              202207L
 // # define __cpp_lib_move_only_function                   202110L
 # undef  __cpp_lib_optional
 # define __cpp_lib_optional                             202110L

libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp

@@ -145,6 +145,7 @@
     __cpp_lib_math_special_functions                        201603L [C++17]
     __cpp_lib_mdspan                                        202207L [C++23]
     __cpp_lib_memory_resource                               201603L [C++17]
+    __cpp_lib_modules                                       202207L [C++23]
     __cpp_lib_move_iterator_concept                         202207L [C++20]
     __cpp_lib_move_only_function                            202110L [C++23]
     __cpp_lib_node_extract                                  201606L [C++17]
@@ -740,6 +741,10 @@
 #   error "__cpp_lib_memory_resource should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_modules
+#   error "__cpp_lib_modules should not be defined before c++23"
+# endif
+
 # ifdef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should not be defined before c++20"
 # endif
@@ -1596,6 +1601,10 @@
 #   error "__cpp_lib_memory_resource should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_modules
+#   error "__cpp_lib_modules should not be defined before c++23"
+# endif
+
 # ifdef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should not be defined before c++20"
 # endif
@@ -2614,6 +2623,10 @@
 #   endif
 # endif
 
+# ifdef __cpp_lib_modules
+#   error "__cpp_lib_modules should not be defined before c++23"
+# endif
+
 # ifdef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should not be defined before c++20"
 # endif
@@ -3917,6 +3930,10 @@
 #   endif
 # endif
 
+# ifdef __cpp_lib_modules
+#   error "__cpp_lib_modules should not be defined before c++23"
+# endif
+
 # ifndef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should be defined in c++20"
 # endif
@@ -5367,6 +5384,13 @@
 #   endif
 # endif
 
+# ifndef __cpp_lib_modules
+#   error "__cpp_lib_modules should be defined in c++23"
+# endif
+# if __cpp_lib_modules != 202207L
+#   error "__cpp_lib_modules should have the value 202207L in c++23"
+# endif
+
 # ifndef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should be defined in c++23"
 # endif
@@ -7153,6 +7177,13 @@
 #   endif
 # endif
 
+# ifndef __cpp_lib_modules
+#   error "__cpp_lib_modules should be defined in c++26"
+# endif
+# if __cpp_lib_modules != 202207L
+#   error "__cpp_lib_modules should have the value 202207L in c++26"
+# endif
+
 # ifndef __cpp_lib_move_iterator_concept
 #   error "__cpp_lib_move_iterator_concept should be defined in c++26"
 # endif

libcxx/utils/generate_feature_test_macro_components.py

@@ -858,6 +858,11 @@ def add_version_header(tc):
             "test_suite_guard": "!defined(_LIBCPP_VERSION) || _LIBCPP_AVAILABILITY_HAS_PMR",
             "libcxx_guard": "_LIBCPP_AVAILABILITY_HAS_PMR",
         },
+        {
+            "name": "__cpp_lib_modules",
+            "values": {"c++23": 202207},
+            "headers": [],
+        },
         {
             "name": "__cpp_lib_move_iterator_concept",
             "values": {"c++20": 202207},