C++20 - cppreference.com (original) (raw)

C++20 is a major version after C++17, featuring major features (concepts, modules, coroutines, and ranges) and other language and library features. The standard was published in December 2020.

Contents

• 1 New language features
• 2 New library features
  • 2.1 New headers
  • 2.2 Library features
• 3 Defect reports
• 4 Compiler support
  • 4.1 C++20 core language features
  • 4.2 C++20 library features
  • 4.3 External links

[edit] New language features

• Feature test macros
• Three-way comparison operator <=> and operator==() = default
• Designated initializers
• Init-statements and initializers in range-for
• char8_t
• New attributes: [[[no_unique_address](language/attributes/no%5Funique%5Faddress.html "cpp/language/attributes/no unique address")]], [[[likely](language/attributes/likely.html "cpp/language/attributes/likely")]], [[[unlikely](language/attributes/likely.html "cpp/language/attributes/likely")]]
• Pack-expansions in lambda init-captures
• Removed the requirement to use typename to disambiguate types in many contexts
• consteval, constinit
• Further relaxed constexpr
• Signed integers are 2's complement
• Bitwise shift operators unified behavior
• aggregate initialization using parentheses
• coroutines
• modules
• Constraints and concepts
• Abbreviated function template
• DR11: array new can deduce array size

[edit] New library features

[edit]

• <source_location>

in Thread support library:

• <stop_token>

[edit] Library features

• Library feature-test macros
• Formatting library
• Concepts library
• Calendar and Time zone library in
• std::source_location
• std::span
• std::endian: big / little / native
• Integral power-of-2 operations and std::bit_cast in
• Array support for std::make_shared
• std::remove_cvref
• std::to_address
• Floating-point atomics, std::shared_ptr atomics
• Thread-coordination classes: std::barrier, std::latch, and std::counting_semaphore
• std::jthread and thread cancellation classes: std::stop_token, std::stop_source, and std::stop_callback
• std::basic_osyncstream
• std::basic_string and other char8_t uses
• constexpr for , ,
• string::starts_with / ends_with and string_view::starts_with / ends_with
• std::assume_aligned
• std::bind_front
• std::c8rtomb / std::mbrtoc8
• std::make_obj_using_allocator etc
• std::make_shared_for_overwrite / std::make_unique_for_overwrite
• Heterogeneous lookup in unordered associative containers
• std::pmr::polymorphic_allocator with additional member functions and std::byte as its default template argument
• execution::unseq
• std::midpoint and std::lerp
• std::ssize
• std::is_bounded_array, std::is_unbounded_array
• Ranges
• Uniform container erasure: std::erase / std::erase_if, e.g. std::erase(std::list) or erase_if(std::map) etc
• Mathematical constants in

[edit] Defect reports

[edit] Compiler support

Main Article: C++20 compiler support

[edit] C++20 core language features

| C++20 feature | Paper(s) | GCC | Clang | MSVC | Apple Clang | EDG eccp | Intel C++ | Nvidia HPC C++ (ex PGI)* | Nvidia nvcc | Cray | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------ | ----------------------------- | ------------------------------ | ---------------------------------------------- | -------------------------- | --------- | ------------------------ | ------------------------- | --------------------- | ---- | | | Allow Lambda capture [=, this] | P0409R2 | 8 | 6 | 19.22* | 10.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | __VA_OPT__ | P0306R4P1042R1 | 8 (partial)*10 (partial)*12 | 9 | 19.25* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Designated initializers (FTM)* | P0329R4 | 4.7 (partial)*8 | 3.0 (partial)*10 | 19.21* | 12.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | template-parameter-list for generic lambdas (FTM)* | P0428R2 | 8 | 9 | 19.22* | 11.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Default member initializers for bit-fields | P0683R1 | 8 | 6 | 19.25* | 10.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Initializer list constructors in class template argument deduction | P0702R1 | 8 | 6 | 19.14* | Yes | 5.0 | 2021.1 | 20.7 | 12.0 | 11.0 | | | const&-qualified pointers to members | P0704R1 | 8 | 6 | 19.0 (2015)* | 10.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Concepts (FTM)* | P0734R0 | 5*10 | 10 | 19.23* (partial)*19.30* | 12.0.0* (partial) | 6.1 | 2023.1* | 20.11 | 12.0 | 11.0 | | | Lambdas in unevaluated contexts | P0315R4 | 9 | 13 (partial)*14 (partial)*17 | 19.28 (16.8)* | 13.1.6* (partial) | 6.2 | 2023.1 (partial)2024.0 | 20.7 | 12.0 | | | | Three-way comparison operator (FTM)* | P0515R3 | 10 | 8 (partial)10 | 19.20* | 12.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | DR11: Simplifying implicit lambda capture | P0588R1 | 8 | | 19.24* | | 5.1 | 2021.1 | 20.7 | 12.0 | | | | init-statements for range-based for | P0614R1 | 9 | 8 | 19.25* | 11.0.0* | 6.0 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Default constructible and assignable stateless lambdas | P0624R2 | 9 | 8 | 19.22* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Type mismatch of defaulted special member functions | P0641R2 | 9 (partial)* | 8 | 19.0 (2015)* (partial)* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Access checking on specializations | P0692R1 | Yes | 8 (partial)14 | 19.26* | 14.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | | | | ADL and function templates that are not visible | P0846R0 | 9 | 9 | 19.21* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | DR11: Specify when constexpr function definitions are needed for constant evaluation (FTM)* | P0859R0 | 5.2 (partial)*9 | 8 | 19.27* (partial)*19.31** | 11.0.0* | (partial) | | | 12.0 | 11.0 | | | Attributes [[likely]] and [[unlikely]] | P0479R5 | 9 | 12 | 19.26* | 13.0.0* | 5.1 | 2021.7 | 20.7 | 12.0 | | | | Make typename more optional | P0634R3 | 9 | 16 | 19.29 (16.10)* | 16.0.0* | 5.1 | 2023.1 | 20.7 | 12.0 | | | | Pack-expansions in lambda init-captures (FTM)* | P0780R2 | 9 | 9 | 19.22* | 11.0.3* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Attribute [[no_unique_address]] | P0840R2 | 9 | 9 | 19.28 (16.9)** | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Conditionally trivial special member functions (FTM)* | P0848R3 | 10 | 16 | 19.28 (16.8)* | | 6.1 | 2021.7 | 20.11 | 12.0 | | | | DR17: Relaxing the structured bindings customization point finding rules | P0961R1 | 8 | 8 | 19.20* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | DR11: Relaxing the range-for loop customization point finding rules | P0962R1 | 8 | 8 | 19.25* | 11.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | DR17: Allow structured bindings to accessible members | P0969R0 | 8 | 8 | 19.20* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Destroying operator delete (FTM)* | P0722R3 | 9 | 6 | 19.27* | 10.0.0* | 6.1 | 2023.1 | 20.11 | 12.0 | 11.0 | | | Class types in Constant template parameters | P0732R2 | 9 | 12 (partial) | 19.26*(partial)*19.28 (16.9)* | 13.0.0* (partial) | 6.2 | 2023.1 (partial) | 21.3 | 12.0 | | | | Deprecate implicit capture of this via [=] | P0806R2 | 9 | 7 | 19.22* | 10.0.1* | 5.1 | | 20.7 | 12.0 | 11.0 | | | explicit(bool) (FTM)* | P0892R2 | 9 | 9 | 19.24* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Integrating feature-test macros | P0941R2 | 5 | 3.4 | 19.15* (partial)19.20* | Yes | 5.0 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Prohibit aggregates with user-declared constructors | P1008R1 | 9 | 8 | 19.20* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | constexpr virtual function (FTM)* | P1064R0 | 9 | 9 | 19.28 (16.9)* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Consistency improvements for comparisons | P1120R0 | 10 | 8 (partial)10 | 19.22* | 12.0.0* | 5.1 | 2023.1 | 20.7 | 12.0 | 11.0 | | | char8_t (FTM)* | P0482R6 | 9 | 7* | 19.22* | 10.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | std::is_constant_evaluated() (FTM)* | P0595R2 | 9 | 9 | 19.25* | 11.0.3* | 5.1 | 19.1 | 21.1 | 12.0 | 11.0 | | | constexpr try-catch blocks | P1002R1 | 9 | 8 | 19.25* | 10.0.1* | 5.1 | 2023.1 | 20.7 | 12.0 | 11.0 | | | Immediate functions (consteval) (FTM)* | P1073R3 | 10 (partial)*11 | 11 (partial)14 (partial)*17 | 19.28 (16.8)*(partial)*19.29 (16.10)* | 11.0.3* (partial)15.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | | | | Nested inline namespaces | P1094R2 | 9 | 8 | 19.27* | 10.0.1* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Yet another approach for constrained declarations | P1141R2 | 10 | 10 | 19.26* (partial)19.28 (16.9)* | 12.0.5* | 6.1 | 2023.1 | 20.11 | 12.0 | 11.0 | | | Signed integers are two's complement | P1236R1 | 9 | 9 | Yes | 11.0.3* | N/A | 2023.1* | yes* | 12.0 | 11.0 | | | dynamic_cast and polymorphic typeid in constant expressions | P1327R1 | 10 | 9 | 19.28 (16.9)* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Changing the active member of a union inside constexpr (FTM)* | P1330R0 | 9 | 9 | 19.10* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Coroutines (FTM)* (FTM)* | P0912R5LWG3393 | 10 | 8 (partial)17 (partial)* | 19.0 (2015)* (partial)19.10**19.28 (16.8)* | 10.0.1* (partial) | 5.1 | 2021.1 | 23.3* | 12.0 (host code only) | | | | Parenthesized initialization of aggregates (FTM)* | P0960R3 | 10 | 16 | 19.28 (16.8)* | 16.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | | | | DR11: Array size deduction in new-expressions | P1009R2 | 11 | 9 | 19.27* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Modules (FTM)* | P1103R3 | 11 (partial) | 8 (partial) | 19.0 (2015)* (partial)19.10**19.28 (16.8)* | 10.0.1* (partial) | | 2023.1 (partial) | | | | | | Stronger Unicode requirements | P1041R4P1139R2 | 10 | Yes | 19.0 (2015)**19.26** | Yes | N/A | 2023.1* | Yes | 12.0 | 11.0 | | | <=> != == | P1185R2 | 10 | 10 | 19.22* | 12.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | DR11: Explicitly defaulted functions with different exception specifications | P1286R2 | 10 | 9 | 19.28 (16.8)* | 11.0.3* | 5.1 | 2021.1 | 20.7 | 12.0 | 11.0 | | | Lambda capture and storage class specifiers of structured bindings | P1091R3P1381R1 | 10 | 8 (partial)16 | 19.11**19.24** | 16.0.0* | 5.1 | 2021.1 | 20.7 | 12.0 | | | | Permit conversions to arrays of unknown bound | P0388R4 | 10 | 14 | 19.27* | 14.0.0* | 6.0 | 2021.5 | 20.11 | 12.0 | | | | constexpr container operations (FTM)* | P0784R7 | 10 | 10 | 19.28 (16.9)* | 12.0.0* | 6.0 | 2021.5 | 20.11 | 12.0 | 11.0 | | | Deprecating some uses of volatile | P1152R4 | 10 | 10 | 19.27* | 12.0.0* | 6.0 | 2021.5 | 20.11 | 12.0 | 11.0 | | | constinit (FTM)* | P1143R2 | 10 | 10 | 19.29 (16.10)* | 12.0.0* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Deprecate comma operator in subscripts | P1161R3 | 10 | 9 | 19.25* | 11.0.3* | 6.0 | 2021.7 | 20.11 | 12.0 | 11.0 | | | [[nodiscard]] with message | P1301R4 | 10 | 9 | 19.25* | 11.0.3* | 6.0 | 2021.5 | 20.11 | 12.0 | 11.0 | | | Trivial default initialization in constexpr functions | P1331R2 | 10 | 10 | 19.27* | 12.0.0* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Unevaluated asm-declaration in constexpr functions | P1668R1 | 10 | 10 | 19.28 (16.9)* | 12.0.0* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | using enum (FTM)* | P1099R5 | 11 | 13 | 19.24* | 13.1.6* | 6.3 | 2023.1 | 22.5 | 12.0 | | | | Synthesizing Three-way comparison for specified comparison category | P1186R3 | 11 | 10 | 19.24* | 12.0.0* | 6.0 | 2021.5 | 20.11 | 12.0 | 11.0 | | | DR17: [[nodiscard]] for constructors | P1771R1 | 10 | 9 | 19.24* | 11.0.3* | 6.0 | 2021.5 | 20.11 | 12.0 | 11.0 | | | class template argument deduction for alias templates (FTM)* | P1814R0 | 10 | 19 | 19.27* | | 6.5 | | 23.9 | 12.0 | | | | class template argument deduction for aggregates (FTM)* | P1816R0P2082R1 | 10*11* | 17 | 19.27* | | 6.3 | 2023.1 (partial)*2024.1 | 23.3 | 12.0 | | | | DR11: Implicit move for more local objects and rvalue references | P1825R0 | 11* | 13 | 19.24* | 13.1.6* | 6.0 | 2021.5 | 20.11 | 12.0 | | | | Allow defaulting comparisons by value | P1946R0 | 10 | 10 | 19.25* | 12.0.0* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Remove std::weak_equality and std::strong_equality | P1959R0 | 10 | 10 | 19.25* | 12.0.0* | 6.1 | 2021.7 | 20.11 | 12.0 | 11.0 | | | Inconsistencies with constant template parameters (FTM)* | P1907R1 | 10 (partial)11 | 18 (partial)* | 19.26* | 13.1.6* (partial) | 6.2 | 2023.1 (partial) | 21.3 | 12.0 | | | | DR98: Pseudo-destructors end object lifetimes | P0593R6 | 11 | 11 | Yes | 12.0.5* | N/A | 2023.1* | Yes | 12.0 | 11.0 | | | DR11: Converting from T* to bool should be considered narrowing | P1957R2 | 10*11* | 11 | 19.27* | 12.0.5* | 6.1 | | | 12.0 | 11.0 | | | C++20 feature | Paper(s) | GCC | Clang | MSVC | Apple Clang | EDG eccp | Intel C++ | Nvidia HPC C++ (ex PGI)* | Nvidia nvcc | Cray | |

[edit] C++20 library features

| C++20 feature | Paper(s) | GCC libstdc++ | Clang libc++ | MSVC STL | Apple Clang* | | | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------ | --------------------------------------------------------------------------------------------------------- | ---------------------------------- | -------------------------- | | | std::endian (FTM)* | P0463R1 | 8 | 7 | 19.22* | 10.0.0* | | | Extending std::make_shared() to support arrays (FTM)* | P0674R1 | 12 | 15 | 19.27* | 14.0.3* | | | Floating-point atomic (FTM)* | P0020R6 | 10 | 18 | 19.22* | 16.0.0* | | | Synchronized buffered (std::basic_osyncstream) (FTM)* | P0053R7 | 11 | 18 | 19.29 (16.10)* | | | | constexpr for and (FTM)* | P0202R3 | 10 | 8 (partial)12 | 19.26* | 10.0.1* (partial)13.0.0* | | | More constexpr for (FTM)* | P0415R1 | 9 | 7 (partial)16 | 19.27* | 10.0.0* (partial)15.0.0* | | | Make std::memory_order a scoped enumeration | P0439R0 | 9 | 9 | 19.25* | 11.0.3* | | | String prefix and suffix checking: string(_view)::starts_with / ends_with (FTM)* | P0457R2 | 9 | 6 | 19.21* | 10.0.0* | | | Library support for operator<=> (FTM)* | P0768R1 | 10 | 7 (partial)12 (partial)*17 | 19.20* (partial)19.28 (16.9)* | 13.0.0* | | | std::remove_cvref (FTM)* | P0550R2 | 9 | 6 | 19.20* | 10.0.0* | | | [[nodiscard]] in the standard library | P0600R1 | 9 | 7 (partial)16 | 19.13* (partial)19.22* | 10.0.0* (partial)15.0.0* | | | Using std::move in numeric algorithms | P0616R0 | 9 | 12 | 19.23* | 13.0.0* | | | Utility to convert a pointer to a raw pointer (FTM)* | P0653R2 | 8 | 6 | 19.22* | Yes | | | Atomic std::shared_ptr and std::weak_ptr (FTM)* | P0718R2 | 12 | | 19.27* | | | | std::span (FTM)* | P0122R7 | 10 | 7 | 19.26* | 10.0.0* | | | Calendar and Time zone (FTM)* | P0355R7 | 11 (partial)*13 (partial)*14 | 7 (partial)19 (partial)* | 19.29 (16.10)* | 10.0.0* (partial) | | | | P0754R2 | 9 | 7 | 19.22* | 10.0.0* | | | Comparing unordered containers | P0809R0 | Yes | Yes | 16.0* | Yes | | | ConstexprIterator requirements (FTM)* (FTM)* | P0858R0 | 9 | 12 | 19.11* | 13.0.0* | | | std::basic_string::reserve() should not shrink | P0966R1 | 11 | 8 | 19.25* | 10.0.1* | | | Atomic Compare-And-Exchange with padding bits | P0528R3 | 13 | | 19.28 (16.8)* | | | | std::atomic_ref (FTM)* | P0019R8 | 10 | 19 | 19.28 (16.8)* | | | | contains() member function of associative containers, e.g. std::map::contains() | P0458R2 | 9 | 13 | 19.21* | 13.1.6* | | | DR11: Guaranteed copy elision for piecewise construction | P0475R1 | 9 | Yes | 19.29 (16.10)* | Yes | | | std::bit_cast() (FTM)* | P0476R2 | 11 | 14 | 19.27* | 14.0.3* | | | Integral power-of-2 operations:std::bit_ceil(),std::bit_floor(),std::bit_width(),std::has_single_bit() (FTM)* | P0556R3P1956R1 | 9*10* | 9*12* | 19.25**19.27**19.28 (16.8)* | 11.0.3**13.0.0** | | | Improving the return value of erase-like algorithms (FTM)* | P0646R1 | 9 | 10 | 19.21* | 12.0.0* | | | std::destroying_delete_t (FTM)* | P0722R3 | 9 | 9 | 19.27* | 11.0.3* | | | std::is_convertible (FTM)* | P0758R1 | 9 | 9 | 19.23* | 11.0.3* | | | Add std::shift_left/right to (FTM)* | P0769R2 | 10 | 12 | 19.21* | 13.0.0* | | | Constexpr for std::swap() and swap related functions | P0879R0 | 10 | 13 | 19.26* | 13.1.6* | | | std::type_identity (FTM)* | P0887R1 | 9 | 8 | 19.21* | 10.0.1* | | | Concepts library (FTM)* | P0898R3 | 10 | 13 | 19.23* | 13.1.6* | | | constexpr comparison operators for std::array | P1023R0 | 10 | 8 | 19.27* | 10.0.1* | | | std::unwrap_ref_decay and std::unwrap_reference (FTM)* | P0318R1 | 9 | 8 | 19.21* | 10.0.1* | | | std::bind_front() (FTM)* | P0356R5 | 9 | 13 | 19.25* | 13.1.6* | | | std::reference_wrapper for incomplete types | P0357R3 | 9 | 8 | 19.26* | 10.0.1* | | | Fixing operator>>(basic_istream&, CharT*) | P0487R1 | 11 | 8 | 19.23* | 10.0.1* | | | Library support for char8_t (FTM)* | P0482R6 | 9 | 8 (partial)16 | 19.22* | 10.0.1* (partial)15.0.0* | | | Utility functions to implement uses-allocator construction | P0591R4 | 9 | 16 | 19.29 (16.10)* | 15.0.0* | | | DR17: std::variant and std::optional should propagate copy/move triviality | P0602R4 | 8.3 | 8 | 19.11* | 10.0.1* | | | DR17: A sane std::variant converting constructor | P0608R3 | 10 | 9 | 19.29 (16.10)**19.42** | 11.0.3* | | | std::function's move constructor should be noexcept | P0771R1 | 7.2 | 6 | 19.22* | Yes | | | The One Ranges Proposal (FTM)* | P0896R4 | 10 | 13 (partial)15* | 19.29 (16.10)* | 14.0.3* | | | Heterogeneous lookup for unordered associative containers (FTM)* | P0919R3P1690R1 | 11 | 12 | 19.23* (P0919R3)19.25* (P1690R1) | 13.0.0* | | | zero(), min(), and max() should be noexcept | P0972R0 | 9 | 8 | 19.14* | 10.0.1* | | | constexpr in std::pointer_traits (FTM)* | P1006R1 | 9 | 8 | 19.26* | 10.0.1* | | | std::assume_aligned() (FTM)* | P1007R3 | 9*11 | 15 | 19.28 (16.9)* | 14.0.3* | | | Smart pointer creation with default initialization (e.g. make_unique_for_overwrite) (FTM)* | P1020R1P1973R1 | 11*12* | 16 | 19.28 (16.9)* | 15.0.0* | | | Misc constexpr bits (FTM)* (FTM)* (FTM)* (FTM)* (FTM)* (FTM)* | P1032R1 | 10 | 13 | 19.28 (16.8)* | 13.1.6* | | | Remove comparison operators of std::span | P1085R2 | 10 | 8 | 19.26* | 10.0.1* | | | Make stateful allocator propagation more consistent for operator+(basic_string) | P1165R1 | 10 | 15 | 19.26* | 14.0.3* | | | Consistent container erasure, e.g. std::erase(std::vector), or std::erase_if(std::map) (FTM)* | P1209R0P1115R3 | 9*10* | 8*11* | 19.25**19.27** | 10.0.1**12.0.5** | | | Standard library header units | P1502R1 | 11 | | 19.29 (16.10)* | | | | polymorphic_allocator<> as a vocabulary type (FTM)* | P0339R6 | 9 | 16 | 19.28 (16.9)* | 15.0.0* | | | std::execution::unseq (FTM)* | P1001R2 | 9 | 17 | 19.28 (16.8)* | | | | std::lerp() and std::midpoint() (FTM)* | P0811R3 | 9 | 9 | 19.23* (partial)19.28 (16.8)* | 11.0.3* | | | Usability enhancements for std::span | P1024R3 | 10 | 9*14 | 19.26* | 11.0.3* | | | DR17: Make std::create_directory() intuitive | P1164R1 | 8.3 | 12 | 19.20* | 13.0.0* | | | std::ssize() and unsigned extent for std::span (FTM)* | P1227R2 | 10 | 9 | 19.25* | 11.0.3* | | | Traits for (un)bounded arrays (FTM)* | P1357R1 | 9 | 9 | 19.25* | 11.0.3* | | | std::to_array() (FTM)* | P0325R4 | 10 | 10 | 19.25* | 12.0.0* | | | Efficient access to std::basic_stringbuf’s buffer | P0408R7 | 11 | 17 | 19.29 (16.10)* | 15.0.0* | | | Layout-compatibility and pointer-interconvertibility traits (FTM)* (FTM)* | P0466R5 | 12 | | 19.29 (16.10)** | | | | Bit operations: std:: rotl(),rotr(),countl_zero(),countl_one(),countr_zero(),countr_one(),popcount() (FTM)* | P0553R4 | 9 | 9 | 19.25**19.28 (16.8)* | 11.0.3* | | | Mathematical constants (FTM)* | P0631R8 | 10 | 11 | 19.25* | 12.0.5* | | | Text formatting (FTM)* | P0645R10 | 13 | 14**17 | 19.29 (16.10)* | 15.0.0* | | | std::stop_token and std::jthread (FTM)* | P0660R10 | 10 | 17(partial)*20* | 19.28 (16.9)* | | | | constexpr std::allocator and related utilities (FTM)* | P0784R7 | 10 | 12 | 19.29 (16.10)* | 13.0.0* | | | constexpr std::string (FTM)* | P0426R1P1032R1P0980R1 | 12 | 15 | 19.29 (16.10)*19.30** | 14.0.3* | | | constexpr std::vector (FTM)* | P1004R2 | 12 | 15 | 19.29 (16.10)*19.30** | 14.0.3* | | | Input range adaptors | P1035R7 | 10 | 16 | 19.29 (16.10)* | 15.0.0* | | | constexpr std::invoke() and related utilities | P1065R2 | 10 | 12 | 19.28 (16.8)* | 13.0.0* | | | Atomic waiting and notifying, std::counting_semaphore, std::latch and std::barrier (FTM)* (FTM)* (FTM)* (FTM)* (FTM)* (FTM)* | P1135R6 | 11 | 11 | 19.28 (16.9)* | 13.1.6* | | | std::source_location (FTM)* | P1208R6 | 11 | 15*(partial)16 | 19.29 (16.10)* | 15.0.0* | | | Adding <=> to the standard library | P1614R2 | 10 | 14*(partial)17*(partial)19 | 19.29 (16.10)* | 13.1.6* (partial) | | | constexpr default constructor of std::atomic and std::atomic_flag (FTM)* | P0883R2 | 10 | 13 | 19.26* | 13.1.6* | | | constexpr for numeric algorithms (FTM)* | P1645R1 | 10 | 12 | 19.26* | 13.0.0* | | | Safe integral comparisons (FTM)* | P0586R2 | 10 | 13 | 19.27* | 13.1.6* | | | C++20 feature | Paper(s) | GCC libstdc++ | Clang libc++ | MSVC STL | Apple Clang* | |

* - hover over a cell marked with the star * to see additional pop-up notes.
DR_nn_ - the number nn after "DR" denotes target C++ revision the Defect Report is applied to, e.g., DR20 → C++20.

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