|  Freestanding  std::mdspan  |  202311L  |  [ ` <mdspan> ` ](/w/cpp/header/mdspan "cpp/header/mdspan") |  (C++26)  |  [ P2833R2 ](https://wg21.link/P2833R2)  
` __cpp_lib_freestanding_memory ` |  Freestanding facilities in [ ` <memory> ` ](/w/cpp/header/memory "cpp/header/memory") |  202306L  |  [ ` <memory> ` ](/w/cpp/header/memory "cpp/header/memory") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_numeric ` |  Freestanding facilities in [ ` <numeric> ` ](/w/cpp/header/numeric "cpp/header/numeric") (saturation arithmetic)  |  202311L  |  [ ` <numeric> ` ](/w/cpp/header/numeric "cpp/header/numeric") |  (C++26)  |  [ P0543R3 ](https://wg21.link/P0543R3)  
` __cpp_lib_freestanding_  operator_new ` |  Definition of  [ operator new ](/w/cpp/memory/new/operator_new "cpp/memory/new/operator new") (optional in freestanding implementations)  |  202306L  |  [ ` <new> ` ](/w/cpp/header/new "cpp/header/new") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_  optional ` |  Making parts of  [ std::optional ](/w/cpp/utility/optional "cpp/utility/optional") freestanding  |  202311L  |  [ ` <optional> ` ](/w/cpp/header/optional "cpp/header/optional") |  (C++26)  |  [ P2407R5 ](https://wg21.link/P2407R5)  
` __cpp_lib_freestanding_ranges ` |  Freestanding facilities in [ ` <ranges> ` ](/w/cpp/header/ranges "cpp/header/ranges") |  202306L  |  [ ` <ranges> ` ](/w/cpp/header/ranges "cpp/header/ranges") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_ratio ` |  Freestanding facilities in [ ` <ratio> ` ](/w/cpp/header/ratio "cpp/header/ratio") |  202306L  |  [ ` <ratio> ` ](/w/cpp/header/ratio "cpp/header/ratio") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_  string_view ` |  Making parts of  [ std::string_view ](/w/cpp/string/basic_string_view "cpp/string/basic string view") freestanding  |  202311L  |  [ ` <string_view> ` ](/w/cpp/header/string_view "cpp/header/string view") |  (C++26)  |  [ P2407R5 ](https://wg21.link/P2407R5)  
` __cpp_lib_freestanding_tuple ` |  Freestanding facilities in [ ` <tuple> ` ](/w/cpp/header/tuple "cpp/header/tuple") |  202306L  |  [ ` <tuple> ` ](/w/cpp/header/tuple "cpp/header/tuple") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_utility ` |  Freestanding facilities in [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  202306L  |  [ ` <utility> ` ](/w/cpp/header/utility "cpp/header/utility") |  (C++26)  |  [ P2198R7 ](https://wg21.link/P2198R7)  
` __cpp_lib_freestanding_variant ` |  Making parts of  [ std::variant ](/w/cpp/utility/variant "cpp/utility/variant") freestanding  |  202311L  |  [ ` <variant> ` ](/w/cpp/header/variant "cpp/header/variant") |  (C++26)  |  [ P2407R5 ](https://wg21.link/P2407R5)  
` __cpp_lib_fstream_  native_handle ` |  Obtaining native handles from file streams  |  202306L  |  [ ` <fstream> ` ](/w/cpp/header/fstream "cpp/header/fstream") |  (C++26)  |  [ P1759R6 ](https://wg21.link/P1759R6)  
` __cpp_lib_function_ref ` |  std::function_ref  : a type-erased callable reference  |  202306L  |  [ ` <functional> ` ](/w/cpp/header/functional "cpp/header/functional") |  (C++26)  |  [ P0792R14 ](https://wg21.link/P0792R14)  
` __cpp_lib_gcd_lcm ` |  [ std::gcd ](/w/cpp/numeric/gcd "cpp/numeric/gcd") ,  [ std::lcm ](/w/cpp/numeric/lcm "cpp/numeric/lcm") |  201606L  |  [ ` <numeric> ` ](/w/cpp/header/numeric "cpp/header/numeric") |  (C++17)  |  [ P0295R0 ](https://wg21.link/P0295R0)  
` __cpp_lib_generator ` |  std::generator  : synchronous coroutine generator for ranges  |  202207L  |  [ ` <generator> ` ](/w/cpp/header/generator "cpp/header/generator") |  (C++23)  |  [ P2502R2 ](https://wg21.link/P2502R2)  
` __cpp_lib_generic_  associative_lookup ` |  Heterogeneous comparison lookup in [ associative containers ](/w/cpp/container#Associative_containers "cpp/container") |  201304L  |  [ ` <map> ` ](/w/cpp/header/ma