") |  (C++20)  |  [ P1001R2 ](https://wg21.link/P1001R2)  
` __cpp_lib_expected ` |  class template  std::expected  |  202202L  |  [ ` <expected> ` ](/w/cpp/header/expected "cpp/header/expected") |  (C++23)  |  [ P0323R12 ](https://wg21.link/P0323R12)  
Monadic functions for  std::expected  |  202211L  |  [ ` <expected> ` ](/w/cpp/header/expected "cpp/header/expected") |  (C++23)  |  [ P2505R5 ](https://wg21.link/P2505R5)  
` __cpp_lib_filesystem ` |  [ Filesystem library ](/w/cpp/filesystem "cpp/filesystem") |  201703L  |  [ ` <filesystem> ` ](/w/cpp/header/filesystem "cpp/header/filesystem") |  (C++17)  |  [ P0218R1 ](https://wg21.link/P0218R1)   
[ P0219R1 ](https://wg21.link/P0219R1)  
[ P0392R0 ](https://wg21.link/P0392R0)  
[ P0317R1 ](https://wg21.link/P0317R1)  
` __cpp_lib_flat_map ` |  [ ` std::flat_map ` ](/w/cpp/container/flat_map "cpp/container/flat map") and [ ` std::flat_multimap ` ](/w/cpp/container/flat_multimap "cpp/container/flat multimap") |  202207L  |  [ ` <flat_map> ` ](/w/cpp/header/flat_map "cpp/header/flat map") |  (C++23)  |  [ P0429R9 ](https://wg21.link/P0429R9)  
` __cpp_lib_flat_set ` |  [ ` std::flat_set ` ](/w/cpp/container/flat_set "cpp/container/flat set") and [ ` std::flat_multiset ` ](/w/cpp/container/flat_multiset "cpp/container/flat multiset") |  202207L  |  [ ` <flat_set> ` ](/w/cpp/header/flat_set "cpp/header/flat set") |  (C++23)  |  [ P1222R4 ](https://wg21.link/P1222R4)   
[ LWG3751 ](https://wg21.link/LWG3751)  
` __cpp_lib_format ` |  [ Text formatting ](/w/cpp/utility/format "cpp/utility/format") |  201907L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++20)  |  [ P0645R10 ](https://wg21.link/P0645R10)   
[ P1361R2 ](https://wg21.link/P1361R2)  
[ P1652R1 ](https://wg21.link/P1652R1)  
Compile-time format string checks; Reducing parameterization of  [ std::vformat_to ](/w/cpp/utility/format/vformat_to "cpp/utility/format/vformat to") |  202106L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++20)    
(DR)  |  [ P2216R3 ](https://wg21.link/P2216R3)  
Fixing locale handling in chrono formatters; Supporting non-const-formattable types  |  202110L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++20)    
(DR)  |  [ P2372R3 ](https://wg21.link/P2372R3)   
[ P2418R2 ](https://wg21.link/P2418R2)  
Exposing [ ` std::basic_format_string ` ](/w/cpp/utility/format/basic_format_string "cpp/utility/format/basic format string") ; clarify handling of encodings in localized formatting of chrono types  |  202207L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++23)  |  [ P2419R2 ](https://wg21.link/P2419R2)   
[ P2508R1 ](https://wg21.link/P2508R1)  
Formatting pointers  |  202304L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++26)  |  [ P2510R3 ](https://wg21.link/P2510R3)  
Type-checking format args  |  202305L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++26)  |  [ P2757R3 ](https://wg21.link/P2757R3)  
Member [ ` visit ` ](/w/cpp/utility/format/basic_format_arg "cpp/utility/format/basic format arg") |  202306L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++26)  |  [ P2637R3 ](https://wg21.link/P2637R3)  
[ Runtime format strings ](/w/cpp/utility/format/runtime_format "cpp/utility/format/runtime format") |  202311L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++26)  |  [ P2918R2 ](https://wg21.link/P2918R2)  
` __cpp_lib_format_ranges ` |  Formatting ranges  |  202207L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++23)  |  [ P2286R8 ](https://wg21.link/P2286R8)   
[ P2585R1 ](https://wg21.link/P2585R1)  
[ LWG3750 ](https://wg21.link/LWG3750)  
` __cpp_lib_format_uchar ` |  Fix formatting of code units as integers  |  202311L  |  [ ` <format> ` ](/w/cpp/header/format "cpp/header/format") |  (C++26)  |  [ P2909R4 ](https://wg21.link/P2909R4)  
` __cpp_lib_formatters ` |  Formatting  [ std::thread::i