[libc++][P0457] add string starts ends with feature test macro

[WimLeflere]

Summary

String(view) starts_with ends_with has been implemented but the feature test macro is missing.
This change adds the feature test macro to the generate script and updates the generated files.

Reference: https://eel.is/c++draft/version.syn

[• Quuxplusone]

LGTM, but redundant with D93830.

[WimLeflere]

Redundant with D93830

libcxx/docs/FeatureTestMacroTable.rst

.. table:: Current Status
     ``__cpp_lib_list_remove_return_type``             ``201806L``
     ------------------------------------------------- -----------------
     ``__cpp_lib_math_constants``                      ``201907L``
     ------------------------------------------------- -----------------
     ``__cpp_lib_ranges``                              *unimplemented*
     ------------------------------------------------- -----------------
     ``__cpp_lib_span``                                ``202002L``
     ------------------------------------------------- -----------------
+    ``__cpp_lib_starts_ends_with``                    ``201711L``
+    ------------------------------------------------- -----------------
     ``__cpp_lib_three_way_comparison``                *unimplemented*
     ------------------------------------------------- -----------------
     ``__cpp_lib_to_array``                            ``201907L``
     ================================================= =================
 

libcxx/include/version

 __cpp_lib_robust_nonmodifying_seq_ops                   201304L <algorithm>
 __cpp_lib_sample                                        201603L <algorithm>
 __cpp_lib_scoped_lock                                   201703L <mutex>
 __cpp_lib_shared_mutex                                  201505L <shared_mutex>
 __cpp_lib_shared_ptr_arrays                             201611L <memory>
 __cpp_lib_shared_ptr_weak_type                          201606L <memory>
 __cpp_lib_shared_timed_mutex                            201402L <shared_mutex>
 __cpp_lib_span                                          202002L <span>
+__cpp_lib_starts_ends_with                              201711L <string> <string_view>
 __cpp_lib_string_udls                                   201304L <string>
 __cpp_lib_string_view                                   201606L <string> <string_view>
 __cpp_lib_three_way_comparison                          201711L <compare>
 __cpp_lib_to_array                                      201907L <array>
 __cpp_lib_to_chars                                      201611L <utility>
 __cpp_lib_transformation_trait_aliases                  201304L <type_traits>
 __cpp_lib_transparent_operators                         201510L <functional>
                                                         201210L // C++14

 #   define __cpp_lib_is_constant_evaluated              201811L
 # endif
 # define __cpp_lib_list_remove_return_type              201806L
 # if defined(__cpp_concepts) && __cpp_concepts >= 201811L
 #   define __cpp_lib_math_constants                     201907L
 # endif
 // # define __cpp_lib_ranges                               201811L
 # define __cpp_lib_span                                 202002L
+# define __cpp_lib_starts_ends_with                     201711L
 // # define __cpp_lib_three_way_comparison                 201711L
 # define __cpp_lib_to_array                             201907L
 #endif
 
 #endif // _LIBCPP_VERSIONH

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

 
 // Test the feature test macros defined by <string>
 
 /*  Constant                                      Value
     __cpp_lib_allocator_traits_is_always_equal    201411L [C++17]
     __cpp_lib_char8_t                             201811L [C++2a]
     __cpp_lib_erase_if                            202002L [C++2a]
     __cpp_lib_nonmember_container_access          201411L [C++17]
+    __cpp_lib_starts_ends_with                    201711L [C++2a]
     __cpp_lib_string_udls                         201304L [C++14]
     __cpp_lib_string_view                         201606L [C++17]
 */
 
 #include <string>
 #include "test_macros.h"
 
 #if TEST_STD_VER < 14

 # ifdef __cpp_lib_erase_if
 #   error "__cpp_lib_erase_if should not be defined before c++2a"
 # endif
 
 # ifdef __cpp_lib_nonmember_container_access
 #   error "__cpp_lib_nonmember_container_access should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifdef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should not be defined before c++14"
 # endif
 
 # ifdef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should not be defined before c++17"
 # endif
 

 # ifdef __cpp_lib_erase_if
 #   error "__cpp_lib_erase_if should not be defined before c++2a"
 # endif
 
 # ifdef __cpp_lib_nonmember_container_access
 #   error "__cpp_lib_nonmember_container_access should not be defined before c++17"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++14"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++14"
 # endif
 
 # ifdef __cpp_lib_string_view

 
 # ifndef __cpp_lib_nonmember_container_access
 #   error "__cpp_lib_nonmember_container_access should be defined in c++17"
 # endif
 # if __cpp_lib_nonmember_container_access != 201411L
 #   error "__cpp_lib_nonmember_container_access should have the value 201411L in c++17"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++17"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++17"
 # endif
 
 # ifndef __cpp_lib_string_view

 
 # ifndef __cpp_lib_nonmember_container_access
 #   error "__cpp_lib_nonmember_container_access should be defined in c++2a"
 # endif
 # if __cpp_lib_nonmember_container_access != 201411L
 #   error "__cpp_lib_nonmember_container_access should have the value 201411L in c++2a"
 # endif
 
+# ifndef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should be defined in c++2a"
+# endif
+# if __cpp_lib_starts_ends_with != 201711L
+#   error "__cpp_lib_starts_ends_with should have the value 201711L in c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++2a"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++2a"
 # endif
 
 # ifndef __cpp_lib_string_view

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

 //===----------------------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
 // WARNING: This test was generated by generate_feature_test_macro_components.py
 // and should not be edited manually.
 
 // <string_view>
 
 // Test the feature test macros defined by <string_view>
 
-/*  Constant                 Value
-    __cpp_lib_char8_t        201811L [C++2a]
-    __cpp_lib_string_view    201606L [C++17]
+/*  Constant                      Value
+    __cpp_lib_char8_t             201811L [C++2a]
+    __cpp_lib_starts_ends_with    201711L [C++2a]
+    __cpp_lib_string_view         201606L [C++17]
 */
 
 #include <string_view>
 #include "test_macros.h"
 
 #if TEST_STD_VER < 14
 
 # ifdef __cpp_lib_char8_t
 #   error "__cpp_lib_char8_t should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifdef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should not be defined before c++17"
 # endif
 
 #elif TEST_STD_VER == 14
 
 # ifdef __cpp_lib_char8_t
 #   error "__cpp_lib_char8_t should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifdef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should not be defined before c++17"
 # endif
 
 #elif TEST_STD_VER == 17
 
 # ifdef __cpp_lib_char8_t
 #   error "__cpp_lib_char8_t should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifndef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should be defined in c++17"
 # endif
 # if __cpp_lib_string_view != 201606L
 #   error "__cpp_lib_string_view should have the value 201606L in c++17"
 # endif
 
 #elif TEST_STD_VER > 17
 
 # if defined(__cpp_char8_t)
 #   ifndef __cpp_lib_char8_t
 #     error "__cpp_lib_char8_t should be defined in c++2a"
 #   endif
 #   if __cpp_lib_char8_t != 201811L
 #     error "__cpp_lib_char8_t should have the value 201811L in c++2a"
 #   endif
 # else
 #   ifdef __cpp_lib_char8_t
 #     error "__cpp_lib_char8_t should not be defined when defined(__cpp_char8_t) is not defined!"
 #   endif
 # endif
 
+# ifndef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should be defined in c++2a"
+# endif
+# if __cpp_lib_starts_ends_with != 201711L
+#   error "__cpp_lib_starts_ends_with should have the value 201711L in c++2a"
+# endif
+
 # ifndef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should be defined in c++2a"
 # endif
 # if __cpp_lib_string_view != 201606L
 #   error "__cpp_lib_string_view should have the value 201606L in c++2a"
 # endif
 
 #endif // TEST_STD_VER > 17
 
 int main(int, char**) { return 0; }

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

/*  Constant                                       Value
     __cpp_lib_robust_nonmodifying_seq_ops          201304L [C++14]
     __cpp_lib_sample                               201603L [C++17]
     __cpp_lib_scoped_lock                          201703L [C++17]
     __cpp_lib_shared_mutex                         201505L [C++17]
     __cpp_lib_shared_ptr_arrays                    201611L [C++17]
     __cpp_lib_shared_ptr_weak_type                 201606L [C++17]
     __cpp_lib_shared_timed_mutex                   201402L [C++14]
     __cpp_lib_span                                 202002L [C++2a]
+    __cpp_lib_starts_ends_with                     201711L [C++2a]
     __cpp_lib_string_udls                          201304L [C++14]
     __cpp_lib_string_view                          201606L [C++17]
     __cpp_lib_three_way_comparison                 201711L [C++2a]
     __cpp_lib_to_array                             201907L [C++2a]
     __cpp_lib_to_chars                             201611L [C++17]
     __cpp_lib_transformation_trait_aliases         201304L [C++14]
     __cpp_lib_transparent_operators                201210L [C++14]
                                                    201510L [C++17]

 # ifdef __cpp_lib_shared_timed_mutex
 #   error "__cpp_lib_shared_timed_mutex should not be defined before c++14"
 # endif
 
 # ifdef __cpp_lib_span
 #   error "__cpp_lib_span should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifdef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should not be defined before c++14"
 # endif
 
 # ifdef __cpp_lib_string_view
 #   error "__cpp_lib_string_view should not be defined before c++17"
 # endif
 

 #     error "__cpp_lib_shared_timed_mutex should not be defined when !defined(_LIBCPP_HAS_NO_THREADS) is not defined!"
 #   endif
 # endif
 
 # ifdef __cpp_lib_span
 #   error "__cpp_lib_span should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++14"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++14"
 # endif
 
 # ifdef __cpp_lib_string_view

 #     error "__cpp_lib_shared_timed_mutex should not be defined when !defined(_LIBCPP_HAS_NO_THREADS) is not defined!"
 #   endif
 # endif
 
 # ifdef __cpp_lib_span
 #   error "__cpp_lib_span should not be defined before c++2a"
 # endif
 
+# ifdef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should not be defined before c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++17"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++17"
 # endif
 
 # ifndef __cpp_lib_string_view

 
 # ifndef __cpp_lib_span
 #   error "__cpp_lib_span should be defined in c++2a"
 # endif
 # if __cpp_lib_span != 202002L
 #   error "__cpp_lib_span should have the value 202002L in c++2a"
 # endif
 
+# ifndef __cpp_lib_starts_ends_with
+#   error "__cpp_lib_starts_ends_with should be defined in c++2a"
+# endif
+# if __cpp_lib_starts_ends_with != 201711L
+#   error "__cpp_lib_starts_ends_with should have the value 201711L in c++2a"
+# endif
+
 # ifndef __cpp_lib_string_udls
 #   error "__cpp_lib_string_udls should be defined in c++2a"
 # endif
 # if __cpp_lib_string_udls != 201304L
 #   error "__cpp_lib_string_udls should have the value 201304L in c++2a"
 # endif
 
 # ifndef __cpp_lib_string_view

libcxx/utils/generate_feature_test_macro_components.py

# C++2a
     "headers": ["atomic", "memory"],
     "unimplemented": True,
     "depends": "!defined(_LIBCPP_HAS_NO_THREADS)",
     "internal_depends": "!defined(_LIBCPP_HAS_NO_THREADS)",
   }, {
     "name": "__cpp_lib_constexpr_dynamic_alloc",
     "values": { "c++2a": int(201907) },
     "headers": ["memory"]
+  }, {
+    "name": "__cpp_lib_starts_ends_with",
+    "values": { "c++2a": int(201711) },
+    "headers": ["string", "string_view"]
   },
 ]], key=lambda tc: tc["name"])
 
 # Map from each header to the Lit annotations that should be used for
 # tests that include that header.
 #
 # For example, when threads are not supported, any feature-test-macro test
 # that includes <thread> should be marked as UNSUPPORTED, because including