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    C++23

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    The current revision of the C++ standard.

    This section is incomplete
    Reason: Check that all significant features are mentioned (using the Compiler Support tables below). Add more links and maybe regroup some lines.

    New language features

    void f(int& x)
    {
    if (x)
    goto END;
    x = 42;
    END:
    }
    • Alias declarations (using) in init-statements (P2360R0), e.g.
    for (using T = int; T e : v)
    /* ... */

    New library features

    New modules

    New headers

    C compatibility headers:

    Library features

    General Utilities
    • std::expected: a new vocabulary type to return a function's result (<expected>) (P0323R12, P2549R1)
    • std::move_only_function: a move-only callable wrapper (P0288R9)
    • std::bind_back: a call wrapper (P2387R3)
    • std::byteswap: reverses the bytes (P1272R4)
    • std::forward_like (P2445R1)
    • std::invoke_r: invokes a Callable object (P2136R3)
    • std::to_underlying: a utility function to get the underlying value of enum (P1682R3)
    • std::unreachable: a function to mark unreachable code (P0627R6)
    • Monadic operations (transform, or_else, and and_then) for std::optional (P0798R8) and std::expected (P2505R5)
    • std::tuple is compatible with other tuple-like objects (P2165R4)
    • Adding default arguments for std::pair's forwarding constructor (P2718R0)
    • std::basic_common_reference specialization for std::reference_wrapper yielding reference types (P2655R3)
    Coroutine Library
    Diagnostic
    Algorithm, Iterators, and Ranges
    • New range adaptors:
    • ranges::range_adaptor_closure: a helper for program-defined range adaptor closures (P2387R3)
    • ranges::to: a range conversion function (P1206R7)
    • New constrained ranges algorithm:
      • ranges::starts_with and ranges::ends_with (P1659R3)
      • ranges::contains and ranges::contains_subrange (P2302R4)
      • ranges::find_last, ranges::find_last_if, and ranges::find_last_if_not (P1223R5)
      • ranges::iota, ranges::shift_left, and ranges::shift_right: rangified versions of non-constrained algorithms (P2440R1)
      • ranges::fold_left etc.: range fold algorithms (P2322R6)
    • Rectifying constant iterators, sentinels, and ranges, that is, ranges::cbegin and other similar utilities returning constant iterators should be fully guaranteed even for shallow-const views (such as std::span) (P2278R4)
    • Making multi-param constructors of some views explicit (P2711R1)
    • Ranges iterators as inputs to non-ranges algorithms (P2408R5)
    • Relaxing range adaptors to allow for move-only types (P2494R2)
    Containers
    • std::mdspan: a non-owning multidimensional array reference (P0009R18, P2599R2, P2604R0, P2613R1, P2763R1)
    • Constructibility and assignability of containers from other compatible ranges (P1206R7)
    • std::flat_set, std::flat_multiset (P1222R4), std::flat_map, std::flat_multimap (P0429R9): flat sets and flat maps - container adaptors wrapping underlying sorted random-access containers
    • Allowing iterator pair construction in std::stack and std::queue (P1425R4)
    • Heterogeneous erasure overloads for associative containers (P2077R2)
    • Non-deduction context for allocators in container deduction guides (P1518R2)
    • Requiring std::span and std::basic_string_view to be trivially copyable (P2251R1)
    Compile-time support
    Memory Management
    • std::out_ptr and std::inout_ptr: smart pointer adaptors for C interoperability (P1132R7)
    • std::allocate_at_least and std::allocator::allocate_at_least (P0401R6)
    • std::start_lifetime_as: an explicit lifetime management function for implicit-lifetime types (P2590R2)
    • Disallowing user specialization of std::allocator_traits (P2652R2)
    String and Text Processing
    • New member functions and changes in string types:
      • std::basic_string::contains and std::basic_string_view::contains (P1679R3)
      • Disabling construction from nullptr for std::basic_string and std::basic_string_view (P2166R1)
      • Explicit range constructor for std::basic_string_view (P1989R2)
      • std::basic_string::resize_and_overwrite (P1072R10)
      • Rvalue reference overload of std::basic_string::substr for efficient slicing (P2438R2)
    • Formatting ranges, tuples, escaped presentation of characters and strings, std::thread::id, and stacktraces. (P2286R8) (P2585R1) (P2693R1)
    I/O and print
    • Formatted output functions std::print and std::println provided in header <print> (P2093R14)
    • spanstream library (std::span-based string stream) provided in header <spanstream> (P0448R4)
    • Support exclusive mode in std::fstreams (P2467R1)
    • Support of printing volatile T*: std::basic_ostream::operator<<(const volatile void*) (P1147R1)

    Obsolete features

    Removed features
    • Garbage collection support and reachability-based leak detection. (P2186R2)
    • Mixed wide string literals concatenation support, e.g., const auto* no = u"q" U"p" is ill-formed. (P2201R1)
    • Non-encodable wide character literals and multicharacter wide character literals, e.g. wchar_t x = 'db' is ill-formed. (P2362R3)
    Deprecated features
    • std::aligned_storage and std::aligned_union (P1413R3)
    • std::numeric_limits::has_denorm (P2614R2)
    Reverted deprecations
    • The operator, (comma operator) in subscript expressions (but the semantics has been changed to support overloadable multidimensional subscript operator[]).
    • Some C headers (the corresponding <*.h> headers for compatibility with C) (P2340R1)

    Defect reports

    Compiler support

    Main Article: C++23 compiler support

    C++23 core language features

    C++23 feature

          		Paper(s)

     
    GCC
    Clang
    MSVC
    Apple Clang
    EDG eccp
    Intel C++
    Nvidia HPC C++ (ex PGI)*
    Nvidia nvcc
    Cray
    Literal suffix for (signed) size_t  (FTM)* P0330R8 11 13 19.43* 13.1.6* 6.5 2022.2 23.9
    Make () more optional for lambdas P1102R2 11 13 19.44* 13.1.6* 6.3 2022.2 22.5
    if consteval  (FTM)* P1938R3 12 14 19.44* 14.0.0* 6.3 2022.2 24.1
    Removing Garbage Collection Support P2186R2 12 N/A 19.30* N/A N/A
    Narrowing contextual conversions in static_assert and constexpr if P1401R5 9 13 (partial)*
    14     		19.44* 14.0.0* 2022.2 20.7
    Trimming whitespaces before line splicing P2223R2 Yes Yes 19.50* Yes 6.7 2022.2 Yes
    Make declaration order layout mandated P1847R4 Yes Yes 19.30* Yes 2022.2 Yes
    Removing mixed wide string literal concatenation P2201R1 Yes Yes 19.44* Yes Yes Yes Yes
    Explicit object member functions (deducing this)  (FTM)* P0847R7 14 18
    19*     		19.32*
    (partial)*
    19.43*     		6.3 22.5
    auto(x) and auto{x}  (FTM)* P0849R8 12 15 19.50* 14.0.3* 6.4 2022.2 23.3
    #elifdef and #elifndef P2334R1 12 13 19.40* 13.1.6* 6.5 2022.2 23.9
    Non-literal variables (and labels and gotos) in constexpr functions  (FTM)* P2242R3 12 15 19.43* 14.0.3* 6.3 2022.2 22.5
    Consistent character literal encoding P2316R2 Yes Yes 19.30* Yes Yes 2022.2 Yes
    Character sets and encodings P2314R4 10 Yes 19.51* Yes Yes 2022.2 Yes
    Extend init-statement (of for loop) to allow alias-declaration P2360R0 12 14 19.50* 14.0.0* 2022.2
    Multidimensional subscript operator  (FTM)* P2128R6 12 15 19.42* 14.0.3* 2022.2
    Attributes on lambdas P2173R1 9 13 19.44* 13.1.6* 6.6 2022.2 22.5
    #warning P2437R1 Yes* Yes 19.50* 15.0.0* 6.5 2023.2 Yes
    Remove non-encodable wide character literals and multicharacter wide character literals P2362R3 13 14 19.51* 15.0.0* 6.7 2023.2
    Labels at the end of compound statements P2324R2 13 16 19.51* 16.0.0* 6.5 2023.2 23.9
    Delimited escape sequences P2290R3 13 15 19.50* 15.0.0* 6.7 2023.2
    Named universal character escapes  (FTM)* P2071R2 13 15 19.51* 15.0.0* 6.7 2023.2
    Relaxing some constexpr restrictions  (FTM)* P2448R2 13 17 (partial)
    19     		19.51* 2024.0 (partial)
    Simpler implicit move  (FTM)* P2266R3 13 13 19.50* 6.7 2022.2
    static operator()  (FTM)* P1169R4 13 16 19.44* 16.0.0* 6.7 2023.2
    Requirements for optional extended floating-point types P1467R9 13 N/A 6.4
    Class template argument deduction from inherited constructors P2582R1 14 19.51*
    Attribute [[assume]] P1774R8 13 19 19.51*
    Support for UTF-8 as a portable source file encoding P2295R6 13* 15* 19.0 (Update 2)** 15.0.0* 2023.2
    static operator[]  (FTM)* P2589R1 13 16 19.44* 16.0.0* 6.7 2023.2
    Permitting static constexpr variables in constexpr functions  (FTM)* P2647R1 13 16 19.51* 16.0.0* 2023.2
    Extending the lifetime of temporaries in range-based for loop initializer  (FTM)* P2644R1
    P2718R0
    CWG2659     		15 19 19.51*
    DR11: Change scope of lambda trailing-return-type P2036R3
    P2579R0     		16 17 19.50* 2023.2
    DR20: Meaningful exports P2615R1 15 17 (partial) 19.28 (16.8)*
    DR20: consteval needs to propagate up  (FTM)* P2564R3 14 17 19.52* 16.0.0* 6.7 2024.0
    DR98: C++ Identifier Syntax using Unicode Standard Annex 31 P1949R7 12 14 19.50* 14.0.0* 6.4 2022.2
    DR11: Allow duplicate attributes P2156R1 11 13 19.50* 13.1.6* 6.5 23.9
    DR20: Adjusting the value of feature-test macro __cpp_concepts P2493R0 12 19.50* 6.4 23.3
    DR98: Relax requirements on wchar_t to match existing practices P2460R2 Yes Yes 19.44* 15.0.0* N/A 2023.2
    DR11: Using unknown pointers and references in constant expressions P2280R4 14 20* 19.50*
    DR20: The Equality Operator You Are Looking For P2468R2 13 16 19.36* 16.0.0* 2023.2
    DR20: char8_t Compatibility and Portability Fix  (FTM)* P2513R4 13 16 19.34* 16.0.0* 2023.2
    DR98/11: Clarify reporting of diagnostic directives and allow static_assert of non-value-dependent expressions in a template context CWG2518 13 17 16.0*
    (partial)*
    19.40*
     

    C++23 feature     		 

    Paper(s)
    GCC
    Clang
    MSVC
    Apple Clang
    EDG eccp
    Intel C++
    Nvidia HPC C++ (ex PGI)*
    Nvidia nvcc
    Cray

    C++23 library features

    C++23 feature

          		Paper(s)

     
    GCC libstdc++
    Clang libc++
    MSVC STL
    Apple Clang*
    Stacktrace library  (FTM)* P0881R7
    P2301R1     		12 (partial)*
    14*     		19.34*
    <stdatomic.h>  (FTM)* P0943R6 12 15 19.31* 14.0.3*
    std::is_scoped_enum  (FTM)* P1048R1 11 12 19.30* 13.0.0*
    std::basic_string::contains(), std::basic_string_view::contains()  (FTM)* P1679R3 11 12 19.30* 13.0.0*
    std::to_underlying  (FTM)* P1682R3 11 13 19.30* 13.1.6*
    Relaxing requirements for std::chrono::time_point P2212R2 N/A N/A N/A N/A
    Providing size feedback in the Allocator interface  (FTM)* P0401R6 16 15 19.30* 14.0.3*
    <spanstream>: string-stream with std::span-based buffer  (FTM)* P0448R4 12 19.31*
    std::out_ptr(), std::inout_ptr()  (FTM)* P1132R8 14 19 19.30*
    constexpr type_info::operator==()  (FTM)* P1328R1 12 17 19.33**
    19.34*     		15.0.0*
    Iterator pair constructors for std::stack and std::queue  (FTM)* P1425R4 12 14 19.31* 14.0.3*
    Non-deduction context for allocators in container deduction guides P1518R2 12* 13* 19.31** 13.1.6**
    ranges::starts_with() and ranges::ends_with()  (FTM)* P1659R3 16 17 (partial)*
    18     		19.31* 16.0.0*
    Prohibiting std::basic_string and std::basic_string_view construction from nullptr P2166R1 12 13 19.30* 13.1.6*
    std::invoke_r()  (FTM)* P2136R3 12 17 19.31* 15.0.0*
    Range constructor for std::basic_string_view P1989R2 11 14 19.30* 14.0.3*
    Default template arguments for std::pair's forwarding constructor P1951R1 14 14 19.30* 14.0.3*
    Remove Garbage Collection and Reachability-Based Leak Detection (library support) P2186R2 12 14 19.30* 14.0.3*
    zip: views::zip, views::zip_transform, views::adjacent, and views::adjacent_transform  (FTM)* P2321R2 13 15 (partial)* 19.33*(partial)***
    19.37*     		14.0.3*
    Heterogeneous erasure overloads for associative containers  (FTM)* P2077R3 16 19.32*
    std::byteswap()  (FTM)* P1272R4 12 14 19.31* 14.0.3*
    Printing volatile T* P1147R1 11.3 14 19.31* 14.0.3*
    basic_string::resize_and_overwrite()  (FTM)* P1072R10 12 14 19.31* 14.0.3*
    Monadic operations for std::optional  (FTM)* P0798R8 12 14 19.32* 14.0.3*
    std::move_only_function  (FTM)* P0288R9 12 19.32*
    Add a conditional noexcept specification to std::exchange P2401R0 12 14 19.31* 14.0.3*
    Require std::span & std::basic_string_view to be TriviallyCopyable P2251R1 Yes Yes 19.31* Yes
    Clarifying the status of the “C headers” P2340R1 Yes Yes Yes Yes
    <expected>  (FTM)* P0323R12
    P2549R1     		12 16 19.33* 15.0.0*
    constexpr for <cmath> and <cstdlib>  (FTM)* P0533R9 4.6 (partial)* 19.52*
    std::unreachable()  (FTM)* P0627R6 12 15 19.32* 14.0.3*
    Deprecating std::aligned_storage and std::aligned_union P1413R3 13 16 19.33*
    std::reference_constructs_from_temporary & std::reference_converts_from_temporary  (FTM)* P2255R2 13 (partial)*
    14     		21 (partial)* 19.51*
    constexpr std::unique_ptr  (FTM)* P2273R3 12 16 19.33* 15.0.0*
    Constructing containers and strings from ranges with ranges::to(), tagged constructors, insert and assign member functions  (FTM)*  (FTM)* P1206R7 14 (partial)*
    15     		17 19.34* 15.0.0*
    Pipe support for user-defined range adaptors (ranges::range_adaptor_closure, std::bind_back)  (FTM)*  (FTM)* P2387R3 13 (partial)*
    14     		19 19.34*
    ranges::iota(), ranges::shift_left(), and ranges::shift_right()  (FTM)*  (FTM)* P2440R1 13 (partial)*
    16     		19.34*
    views::join_with  (FTM)* P2441R2 13 19.34*
    views::chunk and views::slide  (FTM)*  (FTM)* P2442R1 13 19.33*
    views::chunk_by  (FTM)* P2443R1 13 18 19.33* 16.0.0*
    std::mdspan: a non-owning multidimensional array reference  (FTM)* P0009R18
    P2599R2
    P2604R0
    P2613R1
    P2763R1     		16 17 (partial)*
    18     		19.39* 15.0.0*
    <flat_map>  (FTM)* P0429R9 15 20 19.51*
    <flat_set>  (FTM)* P1222R4 15 21 19.51*
    ranges::find_last(), ranges::find_last_if(), and ranges::find_last_if_not()  (FTM)* P1223R5 13 19 19.36*
    Freestanding Library: Easy <utility>, <ranges>, and <iterator> P1642R11 13* 19.38*
    views::stride  (FTM)* P1899R3 13 19.34*
    Compatibility between std::tuple and tuple-like objects  (FTM)* P2165R4 14 2.9 (partial)* 19.36* (partial)*
    19.37*     		partial*
    Rectifying constant iterators, sentinels, and ranges. views::as_const  (FTM)* P2278R4 13 19.35* (partial)*
    19.36*
    Formatting Ranges  (FTM)* P2286R8 15 16 19.37*(partial)*
    19.39*(partial)*
    19.41*(partial)*
    19.42*     		15.0.0*
    Improve default container formatting  (FTM)* P2585R1 15 16 (partial)*
    17     		19.42* 15.0.0*
    Formatted output library <print>  (FTM)* P2093R14
    P2539R4     		14 17 (partial)*
    18     		19.37* 15.0.0**
    16.0.0*
    Formatting std::thread::id and std::stacktrace  (FTM)* P2693R1 14 17 (partial)* 19.38* 15.0.0*
    constexpr for integral overloads of std::to_chars() and std::from_chars()  (FTM)* P2291R3 13 16 19.34* 15.0.0*
    ranges::contains() and ranges::contains_subrange()  (FTM)* P2302R4 13 19 19.34* 16.0.0**
    Ranges fold algorithms  (FTM)* P2322R6 13 19.35*
    views::cartesian_product  (FTM)* P2374R4
    P2540R1     		13 19.37*
    Adding move-only types support for comparison concepts (equality_comparable, totally_ordered, three_way_comparable)  (FTM)* P2404R3 16 19.36*
    Ranges iterators as inputs to non-ranges algorithms  (FTM)* P2408R5 16 19.34*
    constexpr std::bitset  (FTM)* P2417R2 13 16 19.34* 15.0.0*
    basic_string::substr() && P2438R2 16 16 19.34* 15.0.0*
    views::as_rvalue  (FTM)* P2446R2 13 16 19.34* 15.0.0*
    Standard Library Modules  (FTM)* P2465R3 15* 17 (partial)* 19.35*
    (partial)*
    19.36*
    std::forward_like()  (FTM)* P2445R1 14 16 19.34* 15.0.0*
    Support exclusive mode for std::fstream  (FTM)* P2467R1 12 18 19.36* 16.0.0*
    views::repeat  (FTM)* P2474R2 13 17 19.36* 15.0.0*
    Relaxing range adaptors to allow for move-only types  (FTM)* P2494R2 14 17 19.34* 15.0.0*
    std::basic_string_view range constructor should be explicit P2499R0 12.2 16 19.34* 15.0.0*
    std::generator: synchronous coroutine generator for ranges  (FTM)* P2502R2
    P2787R0     		14 19.43*
    Add a conditional noexcept specification to std::apply P2517R1 10 18 19.34* 16.0.0*
    Explicit lifetime management (std::start_lifetime_as)  (FTM)* P2590R2
    P2679R2     		16 19.51*
    Clarify handling of encodings in localized formatting of chrono types  (FTM)* P2419R2 15* 19.34**
    std::move_iterator should not always be input_iterator  (FTM)* P2520R0 12.3* 17* 19.34** 15.0.0*
    Deduction guides update for explicit object parameter call operators LWG3617 14 19.34*
    Deduction guides update for static operator() P1169R4 13 16 19.39* 15.0.0*
    Standard names and library support for extended floating-point types P1467R9 13 19.37**
    Monadic operations for std::expected  (FTM)* P2505R5 13 17 19.36* 15.0.0*
    views::enumerate  (FTM)* P2164R9 13 19.37*
    std::is_implicit_lifetime  (FTM)* P2674R1 16 20 19.51*
    std::common_reference_t of std::reference_wrapper should be a reference type  (FTM)*  (FTM)* P2655R3 16 19.37*
    Disallowing user specialization of std::allocator_traits P2652R2 19 19.37*
    Deprecating std::numeric_limits::has_denorm P2614R2 18 19.37* 16.0.0*
    Making Multi-Param Constructors Of views explicit P2711R1 16 17 (partial)* 19.36** 15.0.0*
    DR20: Relaxing Ranges Just A Smidge  (FTM)* P2609R3 15 20 19.37*
    DR20: Stashing Stashing Iterators For Proper Flattening P2770R0 14 18 19.37*
    DR17: std::visit() for classes derived from std::variant  (FTM)* P2162R2 11.3 13 19.20**
    19.30*     		13.1.6*
    DR20: Conditionally borrowed ranges P2017R1 11 16 19.30*
    DR20: Repairing input range adaptors and std::counted_iterator P2259R1 12 19.30*(partial)*
    19.31*
    DR20: views::join should join all views of ranges P2328R1 11.2 15 19.30* 14.0.3*
    DR20: view does not require default_initializable  (FTM)* P2325R3 11.3 16 19.30* 15.0.0*
    DR20: Range adaptor objects bind arguments by value P2281R1 11 14 19.29 (16.10)*
    (partial)*
    19.31*     		14.0.3*
    DR20: constexpr for std::optional and std::variant  (FTM)*  (FTM)* P2231R1 11.3 (partial)*
    12     		13 (partial)*
    19     		19.31* 13.1.6* (partial)
    DR20: views::lazy_split and redesigned views::split P2210R2 12 16 19.31* 15.0.0*
    DR20: Fix ranges::istream_view P2432R1 12 16 19.31* 15.0.0*
    DR20: view with ownership  (FTM)* P2415R2 12 14 19.31* 14.0.3*
    DR20: Fixing locale handling in chrono formatters  (FTM)* P2372R3
    P2418R2     		13 19.31*
    DR20: Cleaning up integer-class types P2393R1 19.32*
    DR20: Compile-time format string checks; Reducing binary code size of std::format() family  (FTM)* P2216R3 13 14 (partial)*
    15     		19.32* 14.0.3*
    DR20: Add support for non-const-formattable types to std::format P2418R2 13 15 19.32* 14.0.3*
    DR20: std::basic_format_string P2508R1 13 15 19.35* 14.0.3*
    DR20: Poison Pills are Too Toxic  (FTM)* P2602R2 14 19 19.36*
    DR20: std::format fill character allowances P2572R1 14 17 19.37*
    DR20: Improving std::format's width estimation P2675R1 14 17 19.38*
    DR20: std::barrier's phase completion guarantees  (FTM)* P2588R3 19.28 (16.8)**
    19.36*
     

    C++23 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.
    DRnn - the number nn after "DR" denotes target C++ revision the Defect Report is applied to, e.g., DR20 → C++20.

    External links

    1.  C++23 - Wikipedia