Library feature-test macros (since C++20)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Utilities library

Language support Type support (basic types, RTTI) Library feature-test macros(C++20) Program utilities Variadic functions initializer_list (C++11) is_constant_evaluated (C++20) is_within_lifetime (C++26) source_location (C++20) Coroutine support(C++20) Contract support(C++26) Three-way comparison three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20)   is_eqis_ltis_lteq (C++20)(C++20)(C++20)   is_neqis_gtis_gteq (C++20)(C++20)(C++20)

General utilities Function objects Bit manipulation(C++20) bitset hash (C++11) Relational operators(deprecated in C++20) rel_ops::operator!=rel_ops::operator>    rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_lesscmp_less_than (C++20)(C++20)(C++20)   cmp_not_equalcmp_greatercmp_greater_than (C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) to_underlying (C++23) forward (C++11) forward_like (C++23) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) optional (C++17) any (C++17) variant (C++17) tuple_size (C++11) tuple_element (C++11) apply (C++17) make_from_tuple (C++17) expected (C++23)

 

Each of following macros is defined if the header <version> or one of the corresponding headers specified in the table is included.

Macro name	Value	Header	Free- standing
__cpp_lib_adaptor_iterator_pair_constructor	202106L	<stack><queue>
__cpp_lib_addressof_constexpr	201603L	<memory>	Yes
__cpp_lib_algorithm_default_value_type	202403L	<algorithm><ranges><string><deque><list><forward_list><vector>
__cpp_lib_algorithm_iterator_requirements	202207L	<algorithm><numeric><memory>
__cpp_lib_aligned_accessor	202411L	<mdspan>
__cpp_lib_allocate_at_least	202302L	<memory>
__cpp_lib_allocator_traits_is_always_equal	201411L	<memory><scoped_allocator><string><deque><forward_list><list><vector><map><set><unordered_map><unordered_set>	Yes
__cpp_lib_any	201606L	<any>
__cpp_lib_apply	201603L	<tuple>	Yes
__cpp_lib_array_constexpr	201811L	<iterator><array>
__cpp_lib_as_const	201510L	<utility>	Yes
__cpp_lib_associative_heterogeneous_erasure	202110L	<map><set><unordered_map><unordered_set>
__cpp_lib_associative_heterogeneous_insertion	202306L	<map><set><unordered_map><unordered_set>
__cpp_lib_assume_aligned	201811L	<memory>	Yes
__cpp_lib_atomic_flag_test	201907L	<atomic>	Yes
__cpp_lib_atomic_float	201711L	<atomic>	Yes
__cpp_lib_atomic_is_always_lock_free	201603L	<atomic>	Yes
__cpp_lib_atomic_lock_free_type_aliases	201907L	<atomic>
__cpp_lib_atomic_min_max	202403L	<atomic>	Yes
__cpp_lib_atomic_ref	202411L	<atomic>	Yes
__cpp_lib_atomic_shared_ptr	201711L	<memory>
__cpp_lib_atomic_value_initialization	201911L	<atomic><memory>	Yes
__cpp_lib_atomic_wait	201907L	<atomic>	Yes
__cpp_lib_barrier	202302L	<barrier>
__cpp_lib_bind_back	202306L	<functional>	Yes
__cpp_lib_bind_front	202306L	<functional>	Yes
__cpp_lib_bit_cast	201806L	<bit>	Yes
__cpp_lib_bitops	201907L	<bit>	Yes
__cpp_lib_bitset	202306L	<bitset>
__cpp_lib_bool_constant	201505L	<type_traits>	Yes
__cpp_lib_bounded_array_traits	201902L	<type_traits>	Yes
__cpp_lib_boyer_moore_searcher	201603L	<functional>
__cpp_lib_byte	201603L	<cstddef>	Yes
__cpp_lib_byteswap	202110L	<bit>	Yes
__cpp_lib_char8_t	201907L	<atomic><filesystem><istream><limits><locale><ostream><string><string_view>	Yes
__cpp_lib_chrono	202306L	<chrono>
__cpp_lib_chrono_udls	201304L	<chrono>
__cpp_lib_clamp	201603L	<algorithm>
__cpp_lib_common_reference	202302L	<type_traits>	Yes
__cpp_lib_common_reference_wrapper	202302L	<functional>	Yes
__cpp_lib_complex_udls	201309L	<complex>
__cpp_lib_concepts	202207L	<concepts><compare>	Yes
__cpp_lib_constexpr_algorithms	202306L	<algorithm><utility>
__cpp_lib_constexpr_atomic	202411L	<atomic>
__cpp_lib_constexpr_bitset	202207L	<bitset>
__cpp_lib_constexpr_charconv	202207L	<charconv>	Yes
__cpp_lib_constexpr_cmath	202306L	<cmath><cstdlib>
__cpp_lib_constexpr_complex	202306L	<complex>
__cpp_lib_constexpr_deque	202502L	<deque>
__cpp_lib_constexpr_dynamic_alloc	201907L	<memory>
__cpp_lib_constexpr_exceptions	202502L	<exception><stdexcept><expected><optional><variant><format>
__cpp_lib_constexpr_flat_map	202502L	<flat_map>
__cpp_lib_constexpr_flat_set	202502L	<flat_set>
__cpp_lib_constexpr_forward_list	202502L	<forward_list>
__cpp_lib_constexpr_functional	201907L	<functional>	Yes
__cpp_lib_constexpr_inplace_vector	202502L	<inplace_vector>
__cpp_lib_constexpr_iterator	201811L	<iterator>	Yes
__cpp_lib_constexpr_list	202502L	<list>
__cpp_lib_constexpr_map	202502L	<map>
__cpp_lib_constexpr_memory	202202L	<memory>	Yes
__cpp_lib_constexpr_new	202406L	<new>	Yes
__cpp_lib_constexpr_numeric	201911L	<numeric>
__cpp_lib_constexpr_queue	202502L	<queue>
__cpp_lib_constexpr_set	202502L	<set>
__cpp_lib_constexpr_stack	202502L	<stack>
__cpp_lib_constexpr_string	201907L	<string>
__cpp_lib_constexpr_string_view	201811L	<string_view>
__cpp_lib_constexpr_tuple	201811L	<tuple>	Yes
__cpp_lib_constexpr_typeinfo	202106L	<typeinfo>	Yes
__cpp_lib_constexpr_unordered_map	202502L	<unordered_map>
__cpp_lib_constexpr_unordered_set	202502L	<unordered_set>
__cpp_lib_constexpr_utility	201811L	<utility>	Yes
__cpp_lib_constexpr_vector	201907L	<vector>
__cpp_lib_constrained_equality	202411L	<utility><tuple><optional><variant><expected>	Yes
__cpp_lib_containers_ranges	202202L	<vector><list><forward_list><map><set><unordered_map><unordered_set><deque><queue><stack><string>
__cpp_lib_contracts	202502L	<contracts>	Yes
__cpp_lib_copyable_function	202306L	<functional>
__cpp_lib_coroutine	201902L	<coroutine>	Yes
__cpp_lib_debugging	202403L	<debugging>	Yes
__cpp_lib_destroying_delete	201806L	<new>	Yes
__cpp_lib_enable_shared_from_this	201603L	<memory>
__cpp_lib_endian	201907L	<bit>	Yes
__cpp_lib_erase_if	202002L	<string><deque><forward_list><list><vector><map><set><unordered_map><unordered_set>
__cpp_lib_exchange_function	201304L	<utility>	Yes
__cpp_lib_execution	201902L	<execution>
__cpp_lib_expected	202211L	<expected>
__cpp_lib_filesystem	201703L	<filesystem>
__cpp_lib_flat_map	202207L	<flat_map>
__cpp_lib_flat_set	202207L	<flat_set>
__cpp_lib_format	202311L	<format>
__cpp_lib_format_ranges	202207L	<format>
__cpp_lib_format_path	202403L	<filesystem>
__cpp_lib_format_uchar	202311L	<format>
__cpp_lib_formatters	202302L	<stacktrace><thread>
__cpp_lib_forward_like	202207L	<utility>	Yes
__cpp_lib_freestanding_algorithm	202502L	<algorithm>	Yes
__cpp_lib_freestanding_array	202311L	<array>	Yes
__cpp_lib_freestanding_char_traits	202306L	<string>	Yes
__cpp_lib_freestanding_charconv	202306L	<charconv>	Yes
__cpp_lib_freestanding_cstdlib	202306L	<cstdlib><cmath>	Yes
__cpp_lib_freestanding_cstring	202311L	<cstring>	Yes
__cpp_lib_freestanding_cwchar	202306L	<cwchar>	Yes
__cpp_lib_freestanding_errc	202306L	<cerrno><system_error>	Yes
__cpp_lib_freestanding_execution	202502L	<execution>	Yes
__cpp_lib_freestanding_expected	202311L	<expected>	Yes
__cpp_lib_freestanding_feature_test_macros	202306L		Yes
__cpp_lib_freestanding_functional	202306L	<functional>	Yes
__cpp_lib_freestanding_iterator	202306L	<iterator>	Yes
__cpp_lib_freestanding_mdspan	202311L	<mdspan>	Yes
__cpp_lib_freestanding_memory	202502L	<memory>	Yes
__cpp_lib_freestanding_numeric	202502L	<numeric>	Yes
__cpp_lib_freestanding_optional	202311L	<optional>	Yes
__cpp_lib_freestanding_random	202502L	<random>	Yes
__cpp_lib_freestanding_ranges	202306L	<ranges>	Yes
__cpp_lib_freestanding_ratio	202306L	<ratio>	Yes
__cpp_lib_freestanding_string_view	202311L	<string_view>	Yes
__cpp_lib_freestanding_tuple	202306L	<tuple>	Yes
__cpp_lib_freestanding_utility	202306L	<utility>	Yes
__cpp_lib_freestanding_variant	202311L	<variant>	Yes
__cpp_lib_fstream_native_handle	202306L	<fstream>
__cpp_lib_function_ref	202306L	<functional>
__cpp_lib_gcd_lcm	201606L	<numeric>
__cpp_lib_generator	202207L	<generator>
__cpp_lib_generic_associative_lookup	201304L	<map><set>
__cpp_lib_generic_unordered_lookup	201811L	<unordered_map><unordered_set>
__cpp_lib_hardware_interference_size	201703L	<new>	Yes
__cpp_lib_has_unique_object_representations	201606L	<type_traits>	Yes
__cpp_lib_hazard_pointer	202306L	<hazard_pointer>
__cpp_lib_hive	202502L	<hive>
__cpp_lib_hypot	201603L	<cmath>
__cpp_lib_incomplete_container_elements	201505L	<forward_list><list><vector>
__cpp_lib_indirect	202502L	<memory>
__cpp_lib_inplace_vector	202406L	<inplace_vector>
__cpp_lib_int_pow2	202002L	<bit>	Yes
__cpp_lib_integer_comparison_functions	202002L	<utility>
__cpp_lib_integer_sequence	201304L	<utility>	Yes
__cpp_lib_integral_constant_callable	201304L	<type_traits>	Yes
__cpp_lib_interpolate	201902L	<cmath><numeric>
__cpp_lib_invoke	201411L	<functional>	Yes
__cpp_lib_invoke_r	202106L	<functional>	Yes
__cpp_lib_ios_noreplace	202207L	<ios>
__cpp_lib_is_aggregate	201703L	<type_traits>	Yes
__cpp_lib_is_constant_evaluated	201811L	<type_traits>	Yes
__cpp_lib_is_final	201402L	<type_traits>	Yes
__cpp_lib_is_implicit_lifetime	202302L	<type_traits>	Yes
__cpp_lib_is_invocable	201703L	<type_traits>	Yes
__cpp_lib_is_layout_compatible	201907L	<type_traits>	Yes
__cpp_lib_is_nothrow_convertible	201806L	<type_traits>	Yes
__cpp_lib_is_null_pointer	201309L	<type_traits>	Yes
__cpp_lib_is_pointer_interconvertible	201907L	<type_traits>	Yes
__cpp_lib_is_scoped_enum	202011L	<type_traits>	Yes
__cpp_lib_is_sufficiently_aligned	202411L	<memory>
__cpp_lib_is_swappable	201603L	<type_traits>	Yes
__cpp_lib_is_virtual_base_of	202406L	<type_traits>	Yes
__cpp_lib_is_within_lifetime	202306L	<type_traits>	Yes
__cpp_lib_jthread	201911L	<stop_token><thread>
__cpp_lib_latch	201907L	<latch>
__cpp_lib_launder	201606L	<new>	Yes
__cpp_lib_linalg	202412L	<linalg>
__cpp_lib_list_remove_return_type	201806L	<forward_list><list>
__cpp_lib_logical_traits	201510L	<type_traits>	Yes
__cpp_lib_make_from_tuple	201606L	<tuple>	Yes
__cpp_lib_make_reverse_iterator	201402L	<iterator>	Yes
__cpp_lib_make_unique	201304L	<memory>
__cpp_lib_map_try_emplace	201411L	<map>
__cpp_lib_math_constants	201907L	<numbers>
__cpp_lib_math_special_functions	201603L	<cmath>
__cpp_lib_mdspan	202406L	<mdspan>	Yes
__cpp_lib_memory_resource	201603L	<memory_resource>
__cpp_lib_modules	202207L		Yes
__cpp_lib_move_iterator_concept	202207L	<iterator>	Yes
__cpp_lib_move_only_function	202110L	<functional>
__cpp_lib_node_extract	201606L	<map><set><unordered_map><unordered_set>
__cpp_lib_nonmember_container_access	201411L	<array><deque><forward_list><iterator><list><map><regex><set><string><unordered_map><unordered_set><vector>	Yes
__cpp_lib_not_fn	202306L	<functional>	Yes
__cpp_lib_null_iterators	201304L	<iterator>	Yes
__cpp_lib_optional	202110L	<optional>
__cpp_lib_optional_range_support	202406L	<optional>	Yes
__cpp_lib_out_ptr	202311L	<memory>	Yes
__cpp_lib_parallel_algorithm	201603L	<algorithm><numeric>
__cpp_lib_philox_engine	202406L	<random>
__cpp_lib_polymorphic	202502L	<memory>
__cpp_lib_polymorphic_allocator	201902L	<memory_resource>
__cpp_lib_print	202406L	<print><ostream>
__cpp_lib_quoted_string_io	201304L	<iomanip>
__cpp_lib_ranges	202406L	<algorithm><functional><iterator><memory><ranges>
__cpp_lib_ranges_as_const	202311L	<ranges>	Yes
__cpp_lib_ranges_as_rvalue	202207L	<ranges>	Yes
__cpp_lib_ranges_cache_latest	202411L	<ranges>	Yes
__cpp_lib_ranges_cartesian_product	202207L	<ranges>	Yes
__cpp_lib_ranges_chunk	202202L	<ranges>	Yes
__cpp_lib_ranges_chunk_by	202202L	<ranges>	Yes
__cpp_lib_ranges_concat	202403L	<ranges>	Yes
__cpp_lib_ranges_contains	202207L	<algorithm>
__cpp_lib_ranges_enumerate	202302L	<ranges>
__cpp_lib_ranges_find_last	202207L	<algorithm>
__cpp_lib_ranges_fold	202207L	<algorithm>
__cpp_lib_ranges_generate_random	202403L	<random>
__cpp_lib_ranges_iota	202202L	<numeric>
__cpp_lib_ranges_join_with	202202L	<ranges>	Yes
__cpp_lib_ranges_repeat	202207L	<ranges>	Yes
__cpp_lib_ranges_reserve_hint	202502L	<ranges>
__cpp_lib_ranges_slide	202202L	<ranges>	Yes
__cpp_lib_ranges_starts_ends_with	202106L	<algorithm>
__cpp_lib_ranges_stride	202207L	<ranges>	Yes
__cpp_lib_ranges_to_container	202202L	<ranges>	Yes
__cpp_lib_ranges_to_input	202502L	<ranges>	Yes
__cpp_lib_ranges_zip	202110L	<ranges><tuple><utility>	Yes
__cpp_lib_ratio	202306L	<ratio>	Yes
__cpp_lib_raw_memory_algorithms	202411L	<memory>
__cpp_lib_rcu	202306L	<rcu>
__cpp_lib_reference_from_temporary	202202L	<type_traits>	Yes
__cpp_lib_reference_wrapper	202403L	<functional>	Yes
__cpp_lib_remove_cvref	201711L	<type_traits>	Yes
__cpp_lib_result_of_sfinae	201210L	<functional><type_traits>	Yes
__cpp_lib_robust_nonmodifying_seq_ops	201304L	<algorithm>
__cpp_lib_sample	201603L	<algorithm>
__cpp_lib_saturation_arithmetic	202311L	<numeric>
__cpp_lib_scoped_lock	201703L	<mutex>
__cpp_lib_semaphore	201907L	<semaphore>
__cpp_lib_senders	202406L	<execution>
__cpp_lib_shared_mutex	201505L	<shared_mutex>
__cpp_lib_shared_ptr_arrays	201707L	<memory>
__cpp_lib_shared_ptr_weak_type	201606L	<memory>
__cpp_lib_shared_timed_mutex	201402L	<shared_mutex>
__cpp_lib_shift	202202L	<algorithm>
__cpp_lib_simd	202502L	<simd>
__cpp_lib_simd_complex	202502L	<simd>
__cpp_lib_smart_ptr_for_overwrite	202002L	<memory>
__cpp_lib_smart_ptr_owner_equality	202306L	<memory>
__cpp_lib_source_location	201907L	<source_location>	Yes
__cpp_lib_span	202311L	<span>	Yes
__cpp_lib_span_initializer_list	202311L	<span>	Yes
__cpp_lib_spanstream	202106L	<spanstream>
__cpp_lib_ssize	201902L	<iterator>	Yes
__cpp_lib_sstream_from_string_view	202306L	<sstream>
__cpp_lib_stacktrace	202011L	<stacktrace>
__cpp_lib_start_lifetime_as	202207L	<memory>	Yes
__cpp_lib_starts_ends_with	201711L	<string><string_view>
__cpp_lib_stdatomic_h	202011L	<stdatomic.h>
__cpp_lib_string_contains	202011L	<string><string_view>
__cpp_lib_string_resize_and_overwrite	202110L	<string>
__cpp_lib_string_udls	201304L	<string>
__cpp_lib_string_view	202403L	<string><string_view>
__cpp_lib_submdspan	202411L	<mdspan>	Yes
__cpp_lib_syncbuf	201803L	<syncstream>
__cpp_lib_text_encoding	202306L	<text_encoding>
__cpp_lib_three_way_comparison	201907L	<compare>	Yes
__cpp_lib_to_address	201711L	<memory>	Yes
__cpp_lib_to_array	201907L	<array>	Yes
__cpp_lib_to_chars	202306L	<charconv>
__cpp_lib_to_string	202306L	<string>
__cpp_lib_to_underlying	202102L	<utility>	Yes
__cpp_lib_transformation_trait_aliases	201304L	<type_traits>	Yes
__cpp_lib_transparent_operators	201510L	<memory><functional>	Yes
__cpp_lib_trivially_relocatable	202502L	<memory><type_traits>	Yes
__cpp_lib_tuple_element_t	201402L	<tuple>	Yes
__cpp_lib_tuple_like	202311L	<utility><tuple><map><unordered_map>
__cpp_lib_tuples_by_type	201304L	<utility><tuple>	Yes
__cpp_lib_type_identity	201806L	<type_traits>	Yes
__cpp_lib_type_trait_variable_templates	201510L	<type_traits>	Yes
__cpp_lib_uncaught_exceptions	201411L	<exception>	Yes
__cpp_lib_unordered_map_try_emplace	201411L	<unordered_map>
__cpp_lib_unreachable	202202L	<utility>	Yes
__cpp_lib_unwrap_ref	201811L	<type_traits>	Yes
__cpp_lib_variant	202306L	<variant>
__cpp_lib_void_t	201411L	<type_traits>	Yes
Total number of macros: 267

A hardened implementation also defines the following macros:

Macro name	Value	Header	Free- standing
__cpp_lib_hardened_array	202502L	<array>
__cpp_lib_hardened_basic_string	202502L	<string>
__cpp_lib_hardened_basic_string_view	202502L	<string_view>
__cpp_lib_hardened_bitset	202502L	<bitset>
__cpp_lib_hardened_deque	202502L	<deque>
__cpp_lib_hardened_expected	202502L	<expected>
__cpp_lib_hardened_forward_list	202502L	<forward_list>
__cpp_lib_hardened_inplace_vector	202502L	<inplace_vector>
__cpp_lib_hardened_list	202502L	<list>
__cpp_lib_hardened_mdspan	202502L	<mdspan>
__cpp_lib_hardened_optional	202502L	<optional>
__cpp_lib_hardened_span	202502L	<span>
__cpp_lib_hardened_valarray	202502L	<valarray>
__cpp_lib_hardened_vector	202502L	<vector>
Total number of macros: 14

Notes

Each value in "Value" column follows the pattern: "yyyymmL", where "yyyy" is a year, and "mm" is a month when the corresponding feature-set was accepted for standardization. Some values where increased since the time of their introduction, if capabilities of given feature where extended. The table above contains only the most recent values (that is, taken from the latest C++ language draft standard). A full set of values, including the initial and intermediate ones, can be found in this table.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 4126	C++20 C++23	some feature-test macros for fully freestanding features were not freestanding	they are also freestanding

See also

Feature testing(C++20)	A set of preprocessor macros to test the corresponding to C++ language and library features
C++ documentation for Headers required for a freestanding implementation
C++ documentation for Predefined Macro Symbols