ader/functional") |  (C++17)  |  [ N4169 ](https://wg21.link/N4169)  
` __cpp_lib_invoke_r ` |  [ ` std::invoke_r ` ](/w/cpp/utility/functional/invoke "cpp/utility/functional/invoke") |  202106L  |  [ ` <functional> ` ](/w/cpp/header/functional "cpp/header/functional") |  (C++23)  |  [ P2136R3 ](https://wg21.link/P2136R3)  
` __cpp_lib_ios_noreplace ` |  Support [ exclusive mode ](/w/cpp/io/ios_base/openmode "cpp/io/ios base/openmode") for fstreams  |  202207L  |  [ ` <ios> ` ](/w/cpp/header/ios "cpp/header/ios") |  (C++23)  |  [ P2467R1 ](https://wg21.link/P2467R1)  
` __cpp_lib_is_aggregate ` |  [ ` std::is_aggregate ` ](/w/cpp/types/is_aggregate "cpp/types/is aggregate") |  201703L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++17)  |  [ LWG2911 ](https://wg21.link/LWG2911)  
` __cpp_lib_is_constant_  evaluated ` |  [ ` std::is_constant_evaluated ` ](/w/cpp/types/is_constant_evaluated "cpp/types/is constant evaluated") |  201811L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++20)  |  [ P0595R2 ](https://wg21.link/P0595R2)  
` __cpp_lib_is_final ` |  [ std::is_final ](/w/cpp/types/is_final "cpp/types/is final") |  201402L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++14)  |  [ LWG2112 ](https://wg21.link/LWG2112)  
` __cpp_lib_is_implicit_lifetime ` |  [ ` std::is_implicit_lifetime ` ](/w/cpp/types/is_implicit_lifetime "cpp/types/is implicit lifetime") |  202302L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++23)  |  [ P2674R1 ](https://wg21.link/P2674R1)  
` __cpp_lib_is_invocable ` |  std::is_invocable  ,  [ std::invoke_result ](/w/cpp/types/result_of "cpp/types/result of") |  201703L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++17)  |  [ P0604R0 ](https://wg21.link/P0604R0)  
` __cpp_lib_is_layout_compatible ` |  [ ` std::is_layout_compatible ` ](/w/cpp/types/is_layout_compatible "cpp/types/is layout compatible") |  201907L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++20)  |  [ P0466R5 ](https://wg21.link/P0466R5)  
` __cpp_lib_is_nothrow_  convertible ` |  [ ` std::is_nothrow_convertible ` ](/w/cpp/types/is_convertible "cpp/types/is convertible") |  201806L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++20)  |  [ P0758R1 ](https://wg21.link/P0758R1)   
[ LWG3356 ](https://wg21.link/LWG3356)  
` __cpp_lib_is_null_pointer ` |  [ std::is_null_pointer ](/w/cpp/types/is_null_pointer "cpp/types/is null pointer") |  201309L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++14)  |  [ LWG2247 ](https://wg21.link/LWG2247)  
` __cpp_lib_is_pointer_  interconvertible ` |  Pointer-interconvertibility traits: [ ` std::is_pointer_interconvertible_with_class ` ](/w/cpp/types/is_pointer_interconvertible_with_class "cpp/types/is pointer interconvertible with class") , [ ` std::is_pointer_interconvertible_base_of ` ](/w/cpp/types/is_pointer_interconvertible_base_of "cpp/types/is pointer interconvertible base of") |  201907L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++20)  |  [ P0466R5 ](https://wg21.link/P0466R5)  
` __cpp_lib_is_scoped_enum ` |  [ ` std::is_scoped_enum ` ](/w/cpp/types/is_scoped_enum "cpp/types/is scoped enum") |  202011L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++23)  |  [ P1048R1 ](https://wg21.link/P1048R1)  
` __cpp_lib_is_swappable ` |  [ [ ` nothrow ` -]swappable traits ](/w/cpp/types/is_swappable "cpp/types/is swappable") |  201603L  |  [ ` <type_traits> ` ](/w/cpp/header/type_traits "cpp/header/type traits") |  (C++17)  |  [ P0185R1 ](https://wg21.link/P0185R1)  
` __cpp_lib_is_within_lifetime ` |  Checking if a union alternative is active ( [ ` std::is_within_lifetime ` ](/w/cpp/types/is_within_lifetime "cpp/types/is within lifetim