.. _FeatureTestMacroTable:

==========================
Feature Test Macro Support
==========================

.. contents::
   :local:

Overview
========

This file documents the feature test macros currently supported by libc++.

.. _feature-status:

Status
======

.. table:: Current Status
    :name: feature-status-table
    :widths: auto

    =================================================== =================
    Macro Name                                          Value
    =================================================== =================
    **C++ 14**
    ---------------------------------------------------------------------
    ``__cpp_lib_chrono_udls``                           ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_complex_udls``                          ``201309L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_exchange_function``                     ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_generic_associative_lookup``            ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_integer_sequence``                      ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_integral_constant_callable``            ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_final``                              ``201402L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_null_pointer``                       ``201309L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_make_reverse_iterator``                 ``201402L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_make_unique``                           ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_null_iterators``                        ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_quoted_string_io``                      ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_result_of_sfinae``                      ``201210L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_robust_nonmodifying_seq_ops``           ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shared_timed_mutex``                    ``201402L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_string_udls``                           ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_transformation_trait_aliases``          ``201304L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_transparent_operators``                 ``201210L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_tuple_element_t``                       ``201402L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_tuples_by_type``                        ``201304L``
    --------------------------------------------------- -----------------
    **C++ 17**
    ---------------------------------------------------------------------
    ``__cpp_lib_addressof_constexpr``                   ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_allocator_traits_is_always_equal``      ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_any``                                   ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_apply``                                 ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_array_constexpr``                       ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_as_const``                              ``201510L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_is_always_lock_free``            ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bool_constant``                         ``201505L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_boyer_moore_searcher``                  ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_byte``                                  ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_chrono``                                ``201611L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_clamp``                                 ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_enable_shared_from_this``               ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_execution``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_filesystem``                            ``201703L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_gcd_lcm``                               ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_hardware_interference_size``            ``201703L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_has_unique_object_representations``     ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_hypot``                                 ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_incomplete_container_elements``         ``201505L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_invoke``                                ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_aggregate``                          ``201703L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_invocable``                          ``201703L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_swappable``                          ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_launder``                               ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_logical_traits``                        ``201510L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_make_from_tuple``                       ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_map_try_emplace``                       ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_math_special_functions``                *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_memory_resource``                       ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_node_extract``                          ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_nonmember_container_access``            ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_not_fn``                                ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_optional``                              ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_parallel_algorithm``                    *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_raw_memory_algorithms``                 ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_sample``                                ``201603L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_scoped_lock``                           ``201703L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shared_mutex``                          ``201505L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shared_ptr_arrays``                     ``201611L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shared_ptr_weak_type``                  ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_string_view``                           ``201606L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_to_chars``                              *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_transparent_operators``                 ``201510L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_type_trait_variable_templates``         ``201510L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_uncaught_exceptions``                   ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_unordered_map_try_emplace``             ``201411L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_variant``                               ``202102L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_void_t``                                ``201411L``
    --------------------------------------------------- -----------------
    **C++ 20**
    ---------------------------------------------------------------------
    ``__cpp_lib_array_constexpr``                       ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_assume_aligned``                        ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_flag_test``                      ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_float``                          *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_lock_free_type_aliases``         ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_ref``                            *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_shared_ptr``                     *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_value_initialization``           ``201911L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_atomic_wait``                           ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_barrier``                               ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bind_front``                            ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bit_cast``                              ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bitops``                                ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bounded_array_traits``                  ``201902L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_char8_t``                               ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_concepts``                              ``202002L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_algorithms``                  ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_complex``                     ``201711L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_dynamic_alloc``               ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_functional``                  ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_iterator``                    ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_memory``                      ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_numeric``                     ``201911L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_string``                      ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_string_view``                 ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_tuple``                       ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_utility``                     ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_vector``                      ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_coroutine``                             ``201902L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_destroying_delete``                     ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_endian``                                ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_erase_if``                              ``202002L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_execution``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_format``                                *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_generic_unordered_lookup``              ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_int_pow2``                              ``202002L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_integer_comparison_functions``          ``202002L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_interpolate``                           ``201902L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_constant_evaluated``                 ``201811L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_layout_compatible``                  *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_nothrow_convertible``                ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_pointer_interconvertible``           *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_jthread``                               *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_latch``                                 ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_list_remove_return_type``               ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_math_constants``                        ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_move_iterator_concept``                 ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_polymorphic_allocator``                 ``201902L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges``                                ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_remove_cvref``                          ``201711L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_semaphore``                             ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shared_ptr_arrays``                     ``201707L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_shift``                                 ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_smart_ptr_for_overwrite``               *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_source_location``                       ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_span``                                  ``202002L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_ssize``                                 ``201902L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_starts_ends_with``                      ``201711L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_string_view``                           ``201803L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_syncbuf``                               *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_three_way_comparison``                  *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_to_address``                            ``201711L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_to_array``                              ``201907L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_type_identity``                         ``201806L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_unwrap_ref``                            ``201811L``
    --------------------------------------------------- -----------------
    **C++ 23**
    ---------------------------------------------------------------------
    ``__cpp_lib_adaptor_iterator_pair_constructor``     ``202106L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_allocate_at_least``                     ``202106L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_associative_heterogeneous_erasure``     *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_bind_back``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_byteswap``                              ``202110L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_bitset``                      ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_charconv``                    ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_cmath``                       *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_memory``                      ``202202L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_constexpr_typeinfo``                    ``202106L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_expected``                              ``202211L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_format_ranges``                         ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_formatters``                            *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_forward_like``                          ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_invoke_r``                              ``202106L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_is_scoped_enum``                        ``202011L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_mdspan``                                *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_move_only_function``                    *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_optional``                              ``202110L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_out_ptr``                               *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_print``                                 *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_as_rvalue``                      ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_chunk``                          *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_chunk_by``                       *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_iota``                           *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_join_with``                      *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_repeat``                         ``202207L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_slide``                          *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_starts_ends_with``               *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_to_container``                   ``202202L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_ranges_zip``                            *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_reference_from_temporary``              *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_spanstream``                            *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_stacktrace``                            *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_stdatomic_h``                           ``202011L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_string_contains``                       ``202011L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_string_resize_and_overwrite``           ``202110L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_to_string``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_to_underlying``                         ``202102L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_unreachable``                           ``202202L``
    --------------------------------------------------- -----------------
    **C++ 26**
    ---------------------------------------------------------------------
    ``__cpp_lib_associative_heterogeneous_insertion``   *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_bind_back``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_bind_front``                            ``202306L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_bitset``                                *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_copyable_function``                     *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_fstream_native_handle``                 *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_function_ref``                          *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_hazard_pointer``                        *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_ratio``                                 ``202306L``
    --------------------------------------------------- -----------------
    ``__cpp_lib_rcu``                                   *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_smart_ptr_owner_equality``              *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_sstream_from_string_view``              *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_submdspan``                             *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_text_encoding``                         *unimplemented*
    --------------------------------------------------- -----------------
    ``__cpp_lib_within_lifetime``                       *unimplemented*
    =================================================== =================