p "cpp/header/map") [ ` <set> ` ](/w/cpp/header/set "cpp/header/set") |  (C++14)  |  [ N3657 ](https://wg21.link/N3657)  
` __cpp_lib_generic_  unordered_lookup ` |  Heterogeneous comparison lookup in [ unordered associative containers ](/w/cpp/container#Unordered_associative_containers "cpp/container") |  201811L  |  [ ` <unordered_map> ` ](/w/cpp/header/unordered_map "cpp/header/unordered map") [ ` <unordered_set> ` ](/w/cpp/header/unordered_set "cpp/header/unordered set") |  (C++20)  |  [ P0919R3 ](https://wg21.link/P0919R3)  
` __cpp_lib_hardware_  interference_size ` |  [ ` constexpr std::hardware_{constructive, destructive}_interference_size ` ](/w/cpp/thread/hardware_destructive_interference_size "cpp/thread/hardware destructive interference size") |  201703L  |  [ ` <new> ` ](/w/cpp/header/new "cpp/header/new") |  (C++17)  |  [ P0154R1 ](https://wg21.link/P0154R1)  
` __cpp_lib_has_unique_  object_representations ` |  [ std::has_unique_object_representations ](/w/cpp/types/has_unique_object_representations "cpp/types/has unique object representations") |  201606L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++17)  |  [ P0258R2 ](https://wg21.link/P0258R2)  
` __cpp_lib_hazard_pointer ` |  Hazard pointers  |  202306L  |  [ ` <hazard_pointer> ` ](/w/cpp/header/hazard_pointer "cpp/header/hazard pointer") |  (C++26)  |  [ P2530R3 ](https://wg21.link/P2530R3)  
` __cpp_lib_hypot ` |  3-argument overload of  [ std::hypot ](/w/cpp/numeric/math/hypot "cpp/numeric/math/hypot") |  201603L  |  [ ` <cmath> ` ](/w/cpp/header/cmath "cpp/header/cmath") |  (C++17)  |  [ P0030R1 ](https://wg21.link/P0030R1)  
` __cpp_lib_incomplete_  container_elements ` |  Minimal incomplete type support for [ std::forward_list ](/w/cpp/container/forward_list#Template_parameters "cpp/container/forward list") , [ std::list ](/w/cpp/container/list#Template_parameters "cpp/container/list") , and [ std::vector ](/w/cpp/container/vector#Template_parameters "cpp/container/vector") |  201505L  |  [ ` <forward_list> ` ](/w/cpp/header/forward_list "cpp/header/forward list") [ ` <list> ` ](/w/cpp/header/list "cpp/header/list") [ ` <vector> ` ](/w/cpp/header/vector "cpp/header/vector") |  (C++17)  |  [ N4510 ](https://wg21.link/N4510)  
` __cpp_lib_int_pow2 ` |  [ Integral power-of-2 operations ](/w/cpp/numeric#Bit_manipulation_.28since_C.2B.2B20.29 "cpp/numeric") (  std::has_single_bit  ,  std::bit_ceil  ,  std::bit_floor  ,  std::bit_width  )  |  202002L  |  [ ` <bit> ` ](/w/cpp/header/bit "cpp/header/bit") |  (C++20)  |  [ P0556R3 ](https://wg21.link/P0556R3)   
[ P1956R1 ](https://wg21.link/P1956R1)  
` __cpp_lib_integer_  comparison_functions ` |  [ Integer comparison functions ](/w/cpp/utility#Integer_comparison_functions "cpp/utility") |  202002L  |  [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  (C++20)  |  [ P0586R2 ](https://wg21.link/P0586R2)  
` __cpp_lib_integer_sequence ` |  [ Compile-time integer sequences ](/w/cpp/utility/integer_sequence "cpp/utility/integer sequence") |  201304L  |  [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  (C++14)  |  [ N3658 ](https://wg21.link/N3658)  
` __cpp_lib_integral_  constant_callable ` |  [ std::integral_constant::operator() ](/w/cpp/types/integral_constant "cpp/types/integral constant") |  201304L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++14)  |  [ N3545 ](https://wg21.link/N3545)  
` __cpp_lib_interpolate ` |  [ ` std::lerp ` ](/w/cpp/numeric/lerp "cpp/numeric/lerp") , [ ` std::midpoint ` ](/w/cpp/numeric/midpoint "cpp/numeric/midpoint") |  201902L  |  [ ` <cmath> ` ](/w/cpp/header/cmath "cpp/header/cmath") [ ` <numeric> ` ](/w/cpp/header/numeric "cpp/header/numeric") |  (C++20)  |  [ P0811R3 ](https://wg21.link/P0811R3)  
` __cpp_lib_invoke ` |  [ std::invoke ](/w/cpp/utility/functional/invoke "cpp/utility/functional/invoke") |  201411L  |  [ ` <functional> ` ](/w/cpp/header/functional "cpp/he