Library feature-test macros (C++20)

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
`__cpp_lib_addressof_constexpr`	201603L	`<memory>`
`__cpp_lib_allocator_traits_is_always_equal`	201411L	`<memory>` `<scoped_allocator>` `<string>` `<deque>` `<forward_list>` `<list>` `<vector>` `<map>` `<set>` `<unordered_map>` `<unordered_set>`
`__cpp_lib_any`	201606L	`<any>`
`__cpp_lib_apply`	201603L	`<tuple>`
`__cpp_lib_array_constexpr`	201603L	`<iterator>` `<array>`
`__cpp_lib_as_const`	201510L	`<utility>`
`__cpp_lib_atomic_is_always_lock_free`	201603L	`<atomic>`
`__cpp_lib_atomic_ref`	201806L	`<atomic>`
`__cpp_lib_bit_cast`	201806L	`<bit>`
`__cpp_lib_bind_front`	201811L	`<functional>`
`__cpp_lib_bool_constant`	201505L	`<type_traits>`
`__cpp_lib_bounded_array_traits`	201902L	`<type_traits>`
`__cpp_lib_boyer_moore_searcher`	201603L	`<functional>`
`__cpp_lib_byte`	201603L	`<cstddef>`
`__cpp_lib_char8_t`	201811L	`<atomic>` `<filesystem>` `<istream>` `<limits>` `<locale>` `<ostream>` `<string>` `<string_view>`
`__cpp_lib_chrono`	201611L	`<chrono>`
`__cpp_lib_clamp`	201603L	`<algorithm>`
`__cpp_lib_complex_udls`	201309L	`<complex>`
`__cpp_lib_concepts`	201806L	`<concepts>`
`__cpp_lib_constexpr_misc`	201811L	`<array>` `<functional>` `<iterator>` `<string_view>` `<tuple>` `<utility>`
`__cpp_lib_constexpr_swap_algorithms`	201806L	`<algorithm>`
`__cpp_lib_enable_shared_from_this`	201603L	`<memory>`
`__cpp_lib_erase_if`	201811L	`<string>` `<deque>` `<forward_list>` `<list>` `<vector>` `<map>` `<set>` `<unordered_map>` `<unordered_set>`
`__cpp_lib_exchange_function`	201304L	`<utility>`
`__cpp_lib_execution`	201902L	`<execution>`
`__cpp_lib_filesystem`	201703L	`<filesystem>`
`__cpp_lib_gcd_lcm`	201606L	`<numeric>`
`__cpp_lib_generic_associative_lookup`	201304L	`<map>` `<set>`
`__cpp_lib_generic_unordered_lookup`	201811L	`<unordered_map>` `<unordered_set>`
`__cpp_lib_generic_unordered_hash_lookup`	201902L	`<unordered_map>` `<unordered_set>`
`__cpp_lib_hardware_interference_size`	201703L	`<new>`
`__cpp_lib_has_unique_object_representations`	201606L	`<type_traits>`
`__cpp_lib_hypot`	201603L	`<cmath>`
`__cpp_lib_incomplete_container_elements`	201505L	`<forward_list>` `<list>` `<vector>`
`__cpp_lib_integer_sequence`	201304L	`<utility>`
`__cpp_lib_integral_constant_callable`	201304L	`<type_traits>`
`__cpp_lib_invoke`	201411L	`<functional>`
`__cpp_lib_interpolate`	201902L	`<cmath>` `<numeric>`
`__cpp_lib_is_constant_evaluated`	201811L	`<type_traits>`
`__cpp_lib_is_aggregate`	201703L	`<type_traits>`
`__cpp_lib_is_final`	201402L	`<type_traits>`
`__cpp_lib_is_invocable`	201703L	`<type_traits>`
`__cpp_lib_is_null_pointer`	201309L	`<type_traits>`
`__cpp_lib_is_swappable`	201603L	`<type_traits>`
`__cpp_lib_launder`	201606L	`<new>`
`__cpp_lib_list_remove_return_type`	201806L	`<forward_list>` `<list>`
`__cpp_lib_logical_traits`	201510L	`<type_traits>`
`__cpp_lib_make_from_tuple`	201606L	`<tuple>`
`__cpp_lib_make_reverse_iterator`	201402L	`<iterator>`
`__cpp_lib_make_unique`	201304L	`<memory>`
`__cpp_lib_map_try_emplace`	201411L	`<map>`
`__cpp_lib_math_special_functions`	201603L	`<cmath>`
`__cpp_lib_memory_resource`	201603L	`<memory_resource>`
`__cpp_lib_node_extract`	201606L	`<map>` `<set>` `<unordered_map>` `<unordered_set>`
`__cpp_lib_nonmember_container_access`	201411L	`<iterator>` `<array>` `<deque>` `<forward_list>` `<list>` `<map>` `<regex>` `<set>` `<string>` `<unordered_map>` `<unordered_set>` `<vector>`
`__cpp_lib_not_fn`	201603L	`<functional>`
`__cpp_lib_null_iterators`	201304L	`<iterator>`
`__cpp_lib_optional`	201606L	`<optional>`
`__cpp_lib_parallel_algorithm`	201603L	`<algorithm>` `<numeric>`
`__cpp_lib_quoted_string_io`	201304L	`<iomanip>`
`__cpp_lib_ranges`	201811L	`<algorithm>` `<functional>` `<iterator>` `<memory>` `<ranges>`
`__cpp_lib_raw_memory_algorithms`	201606L	`<memory>`
`__cpp_lib_result_of_sfinae`	201210L	`<functional>` `<type_traits>`
`__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_string_udls`	201304L	`<string>`
`__cpp_lib_string_view`	201606L	`<string>` `<string_view>`
`__cpp_lib_three_way_comparison`	201711L	`<compare>`
`__cpp_lib_to_chars`	201611L	`<utility>`
`__cpp_lib_transformation_trait_aliases`	201304L	`<type_traits>`
`__cpp_lib_transparent_operators`	201510L	`<memory>` `<functional>`
`__cpp_lib_tuple_element_t`	201402L	`<tuple>`
`__cpp_lib_tuples_by_type`	201304L	`<utility>` `<tuple>`
`__cpp_lib_type_trait_variable_templates`	201510L	`<type_traits>`
`__cpp_lib_uncaught_exceptions`	201411L	`<exception>`
`__cpp_lib_unordered_map_try_emplace`	201411L	`<unordered_map>`
`__cpp_lib_variant`	201606L	`<variant>`
`__cpp_lib_void_t`	201411L	`<type_traits>`

Language
Standard Library Headers
Freestanding and hosted implementations
Named requirements
Language support library
Concepts library (C++20)
Diagnostics library
Utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications