features_cpp23.yaml

---
features:
  - desc: "Literal suffix for (signed) `size_t` (`uz/t`)"
    paper: P0330
    summary: "New literal suffixes `uz` (unsigned) and `z` (signed) for size types."
    support:
      - GCC 11
      - Clang 13
      - MSVC 14.43
      - Xcode 13.4.1
    ftm:
      - name: __cpp_size_t_suffix
        value: 202011L
    content: literal-suffix-size-t.md

  - desc: "`std::basic_string::contains()` and `std::basic_string_view::contains()`"
    paper: P1679
    lib: true
    support:
      - GCC 11
      - Clang 12
      - MSVC 14.30
      - Xcode 13
    ftm:
      - name: __cpp_lib_string_contains
        value: 202011L

  - desc: "`<stacktrace>`"
    paper: P0881
    content: stacktrace.md
    lib: true
    support:
      - GCC 12 (partial)
      - GCC 14
      - MSVC 14.34
    hints:
      - target: GCC 12
        msg: "Enabled by building GCC with `--enable-libstdcxx-backtrace=yes`, requires linking against `-lstdc++_libbacktrace`"
    ftm:
      - name: __cpp_lib_stacktrace
        value: 202011L

  - desc: "`std::is_scoped_enum`"
    paper: P1048
    lib: true
    support:
      - GCC 11
      - Clang 12
      - MSVC 14.30
      - Xcode 13
    ftm:
      - name: __cpp_lib_is_scoped_enum
        value: 202011L

  - desc: "`<stdatomic.h>`"
    paper: P0943
    lib: true
    support:
      - GCC 12
      - Clang 15
      - MSVC 14.31
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_stdatomic_h
        value: 202011L

  - desc: "_Down with ()!_ (relax `()` rules for lambdas)"
    paper: P1102
    summary: "Empty parameter parentheses can be omitted from lambdas with specifiers."
    support:
      - GCC 11
      - Clang 13
      - MSVC 14.44
      - Xcode 13.4.1

  - desc: "Repairing input range adaptors and `std::counted_iterator`"
    paper: P2259
    lib: true
    support:
      - GCC 12
      - MSVC 14.30 (partial)
      - MSVC 14.31
    hints:
      - target: MSVC 14.30
        msg: "The counted_iterator part is implemented; the input range adaptors part is not implemented yet."

  - desc: "Relaxing requirements for `chrono::time_point::clock`"
    paper: P2212
    lib: true
    support:
      - MSVC
      - GCC 11
      - Clang 17
      - Xcode 16.1

  - desc: "`std::visit()` for classes derived from `std::variant`"
    paper: P2162
    lib: true
    support:
      - GCC 11.3
      - Clang 13
      - MSVC 14.20
      - MSVC 14.30
      - Xcode 16.1
    ftm:
      - name: __cpp_lib_variant
        value: 202102L

  - desc: "Conditionally borrowed ranges"
    paper: P2017
    lib: true
    support:
      - GCC 11
      - Clang 16
      - MSVC 14.30
      - Xcode 16.1

  - desc: "`std::to_underlying()`"
    paper: P1682
    lib: true
    support:
      - GCC 11
      - Clang 13
      - MSVC 14.30
      - Xcode 13.4.1
    ftm:
      - name: __cpp_lib_to_underlying
        value: 202102L

  - desc: "`if consteval`"
    paper: P1938
    summary: "Detect at compile time whether code is being constant-evaluated."
    content: if-consteval.md
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.44
      - Xcode 14
    ftm:
      - name: __cpp_if_consteval
        value: 202106L

  - desc: "C++ identifier syntax using Unicode Standard Annex 31"
    paper: P1949
    support:
      - GCC 12
      - Clang 14
      - Xcode 14
      - MSVC 14.50

  - desc: "Allow duplicate attributes"
    paper: P2156
    support:
      - GCC 11
      - Clang 13
      - Xcode 13.4.1
      - MSVC 14.50

  - desc: "Narrowing contextual conversions to `bool` (in `static_assert` and `constexpr if`)"
    paper: P1401
    support:
      - GCC 9
      - Clang 13 (partial)
      - Clang 14
      - MSVC 14.21 (hint)
      - MSVC 14.44
      - Xcode 14
    hints:
      - target: Clang 13
        msg: "noexcept specifiers changes missing"
      - target: MSVC 14.21
        msg: "Compiles, but emits a warning: warning C4305: 'if': truncation from 'int' to 'bool'"

  - desc: "Trimming whitespaces before line splicing"
    paper: P2223
    support:
      - GCC
      - Clang
      - Xcode
      - MSVC 14.50

  - desc: "Make declaration order layout mandated"
    paper: P1847
    support:
      - GCC
      - Clang
      - MSVC 14.30
      - Xcode

  - desc: "Remove mixed wide string literal concatenation"
    paper: P2201
    support:
      - GCC
      - Clang
      - MSVC 14.44
      - Xcode

  - desc: "`std::out_ptr()` and `std::inout_ptr()`"
    paper: P1132
    lib: true
    support:
      - GCC 14
      - Clang 19
      - MSVC 14.30
      - Xcode 16.4
    ftm:
      - name: __cpp_lib_out_ptr
        value: 202106L

  - desc: "`constexpr` `std::type_info::operator==()`"
    paper: P1328
    lib: true
    support:
      - GCC 12
      - Clang 17
      - MSVC 14.33
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_constexpr_typeinfo
        value: 202106L

  - desc: "`<spanstream>`: stringstream with `std::span`-based buffer"
    paper: P0448
    lib: true
    support: [GCC 12, MSVC 14.31]
    ftm:
      - name: __cpp_lib_spanstream
        value: 202106L

  - desc: "Iterator pair constructors for `std::stack` and `std::queue`"
    paper: P1425
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_adaptor_iterator_pair_constructor
        value: 202106L

  - desc: "Non-deduction context for allocators in container deduction guides"
    paper: P1518
    lib: true
    support:
      - GCC 12
      - Clang 13
      - MSVC 14.31
      - Xcode 13.4.1

  - desc: "Providing size feedback in the Allocator interface"
    paper: P0401
    lib: true
    support:
      - Clang 15
      - MSVC 14.30
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_allocate_at_least
        value: 202302L

  - desc: "`ranges::starts_with()` and `ranges::ends_with()`"
    paper: P1659
    lib: true
    support:
      - GCC 16
      - Clang 17 (partial)
      - Clang 19
      - MSVC 14.31
      - Xcode 16
    hints:
      - target: Clang 17
        msg: "Implements `std::ranges::starts_with()` only."
    ftm:
      - name: __cpp_lib_ranges_starts_ends_with
        value: 202106L

  - desc: "Default template arguments for `std::pair`'s forwarding constructor"
    paper: P1951
    lib: true
    support:
      - GCC 14
      - Clang 14
      - MSVC 14.30
      - Xcode 14.3

  - desc: "Range constructor for `std::basic_string_view`"
    paper: P1989
    lib: true
    support:
      - GCC 11
      - Clang 14
      - MSVC 14.30
      - Xcode 14.3

  - desc: "`std::invoke_r()`"
    paper: P2136
    lib: true
    support:
      - GCC 12
      - Clang 17
      - MSVC 14.31
      - Xcode 15
    ftm:
      - name: __cpp_lib_invoke_r
        value: 202106L

  - desc: "Prohibiting `std::basic_string` and `std::basic_string_view` construction from `nullptr`"
    paper: P2166
    lib: true
    support:
      - GCC 12
      - Clang 13
      - MSVC 14.30
      - Xcode 13.4.1

  - desc: "`constexpr` `std::optional` and `std::variant`"
    paper: P2231
    lib: true
    support:
      - GCC 11.3 (partial)
      - GCC 12
      - Clang 13 (partial)
      - Clang 19
      - MSVC 14.31
      - Xcode 13.4.1 (partial)
      - Xcode 16.3
    hints:
      - target: GCC 11.3
        msg: "Only the `std::optional` part is implemented."
      - target: Clang 13
        msg: "Only the `std::optional` part is implemented."
      - target: Xcode 13.4.1
        msg: "Only the `std::optional` part is implemented."
    ftm:
      - name: __cpp_lib_optional
        value: 202106L
        desc: "`constexpr` `std::optional` is available"
      - name: __cpp_lib_variant
        value: 202106L
        desc: "`constexpr` `std::variant` is available"

  - desc: "`std::format()` improvements"
    paper: P2216
    lib: true
    support:
      - GCC 13
      - Clang 15
      - MSVC 14.32
      - Xcode 14.3

  - desc: "Range adaptor objects bind arguments by value"
    paper: P2281
    lib: true
    support:
      - GCC 11
      - Clang 14
      - MSVC 14.29 (partial)
      - MSVC 14.31
      - Xcode 14.3
    hints:
      - target: MSVC 14.29
        msg: "The split_view part is missing."

  - desc: "`views::join()` should join all views of ranges"
    paper: P2328
    lib: true
    support:
      - GCC 11.2
      - Clang 15
      - MSVC 14.30
      - Xcode 14.3

  - desc: "Views should not be required to be default-constructible"
    paper: P2325
    lib: true
    support:
      - GCC 11.3
      - Clang 16
      - MSVC 14.30
      - Xcode 15
    ftm:
      - name: __cpp_lib_ranges
        value: 202106L

  - desc: "Superior string splitting (`views::lazy_split()` and redesigned `views::split()`)"
    paper: P2210
    lib: true
    support:
      - GCC 12
      - Clang 16
      - MSVC 14.31
      - Xcode 15

  - desc: "Non-literal variables (and labels and gotos) in `constexpr` functions"
    paper: P2242
    summary: "constexpr functions can contain non-literal variables on non-evaluated paths."
    support:
      - GCC 12
      - Clang 15
      - MSVC 14.43
      - Xcode 14.3
    ftm:
      - name: __cpp_constexpr
        value: 202110L

  - desc: "Explicit object member functions (deducing `this`)"
    paper: P0847
    summary: 'Member functions can now have an explicit "self" parameter, enabling perfect forwarding and CRTP simplification.'
    content: deducing-this.md
    support:
      - GCC 14
      - Clang 18 (partial)
      - Clang 19 (partial)
      - Clang 20
      - MSVC 14.32
      - MSVC 14.43
      - Xcode 16.3
    hints:
      - target: Clang 18
        msg: "Experimental support. Lacks P2797 and the FTM `__cpp_explicit_this_parameter`. Its support can be tested with `__has_extension(cxx_explicit_this_parameter)`."
      - target: Clang 19
        msg: "Completes core language support (P2797), but still lacks the FTM `__cpp_explicit_this_parameter`."
    ftm:
      - name: __cpp_explicit_this_parameter
        value: 202110L

  - desc: "Consistent character literal encoding"
    paper: P2316
    support:
      - GCC
      - Clang
      - MSVC 14.30
      - Xcode

  - desc: "Add support for preprocessing directives `#elifdef` and `#elifndef`"
    paper: P2334
    summary: "Shorthand preprocessor directives combining `#elif` and `#ifdef`/`#ifndef`."
    support:
      - GCC 12
      - Clang 13
      - MSVC 14.40
      - Xcode 13.4.1

  - desc: "Extend init-statement (of `for` loop) to allow alias-declaration"
    paper: P2360
    summary: "Range-based for can declare type aliases in the init-statement."
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.50 (hint)
      - Xcode 14
    hints:
      - target: MSVC 14.50
        msg: "Compiles, but no IntelliSense support yet."

  - desc: "Change scope of lambda trailing-return-type"
    paper: [P2036, P2579]
    support:
      - GCC 16
      - Clang 17
      - Xcode 16.3
      - MSVC 14.50

  - desc: "Multidimensional subscript operator (`operator[x, y]`)"
    paper: P2128
    summary: "`operator[]` can now take multiple arguments."
    content: multidim-subscript.md
    support:
      - GCC 12
      - Clang 15
      - MSVC 14.42
      - Xcode 14.3
    ftm:
      - name: __cpp_multidimensional_subscript
        value: 202110L

  - desc: "Character encoding of diagnostic text"
    paper: P2246
    support:
      - GCC 16
      - Clang
      - MSVC 14.30
      - Xcode

  - desc: "Character sets and encodings"
    paper: P2314
    support:
      - GCC 10
      - Clang
      - Xcode

  - desc: "Fixing locale handling in chrono formatters"
    paper: P2372
    lib: true
    support:
      - GCC 13
      - Clang 21
      - MSVC 14.31
      - Xcode 16.1

  - desc: "What is a view?"
    paper: P2415
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3

  - desc: "Add support for `std::generator`-like types to `std::format()`"
    paper: P2418
    lib: true
    support:
      - GCC 13
      - Clang 15
      - MSVC 14.32
      - Xcode 14.3

  - desc: "Fix `ranges::istream_view`"
    paper: P2432
    lib: true
    support:
      - GCC 12
      - Clang 16
      - MSVC 14.31
      - Xcode 15

  - desc: "`std::move_only_function`"
    paper: P0288
    lib: true
    support:
      - GCC 12
      - MSVC 14.32
    ftm:
      - name: __cpp_lib_move_only_function
        value: 202110L

  - desc: "Monadic operations for `std::optional` (`and_then()`, `or_else()`, `transform()`)"
    paper: P0798
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.32
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_optional
        value: 202110L

  - desc: "Decay-copy in the language (`auto(x)` and `auto{x}`)"
    paper: P0849
    summary: "Create a decayed copy of an expression."
    support:
      - GCC 12
      - Clang 15
      - MSVC 14.50
      - Xcode 14.3
    ftm:
      - name: __cpp_auto_cast
        value: 202110L

  - desc: "`std::basic_string::resize_and_overwrite()`"
    paper: P1072
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_string_resize_and_overwrite
        value: 202110L

  - desc: "Printing volatile `T*`"
    paper: P1147
    lib: true
    support:
      - GCC 11.3
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3

  - desc: "`std::byteswap()`"
    paper: P1272
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_byteswap
        value: 202110L

  - desc: "Heterogeneous erasure overloads for associative containers"
    paper: P2077
    lib: true
    support: [MSVC 14.32]
    ftm:
      - name: __cpp_lib_associative_heterogeneous_erasure
        value: 202110L
    keywords: ["erase"]

  - desc: "Require `std::span` and `std::basic_string_view` to be [TriviallyCopyable](https://en.cppreference.com/w/cpp/named_req/TriviallyCopyable)"
    paper: P2251
    lib: true
    support:
      - GCC
      - Clang
      - MSVC 14.31
      - Xcode

  - desc: "Add a `pmr` alias for `std::stacktrace`"
    paper: P2301
    lib: true
    support:
      - GCC 12 (partial)
      - GCC 14
      - MSVC 14.34
    hints:
      - target: GCC 12
        msg: "Enabled by building GCC with `--enable-libstdcxx-backtrace=yes`, requires linking against `-lstdc++_libbacktrace`"
    ftm:
      - name: __cpp_lib_stacktrace
        value: 202011L

  - desc: "zip: `views::zip()`, `views::zip_transform()`, `views::adjacent()` and `views::adjacent_transform()`"
    paper: P2321
    lib: true
    support:
      - GCC 13
      - Clang 15 (partial)
      - Clang 22
      - MSVC 14.37
      - Xcode 14.3
    hints:
      - target: Clang 15
        msg: "Only implements tuple specializations and `views::zip()`."
    ftm:
      - name: __cpp_lib_ranges_zip
        value: 202110L

  - desc: "Cleaning up integer-class types"
    paper: P2393
    lib: true
    support: [MSVC 14.32]

  - desc: "Add a conditional `noexcept` specification to `std::exchange()`"
    paper: P2401
    lib: true
    support:
      - GCC 12
      - Clang 14
      - MSVC 14.31
      - Xcode 14.3

  - desc: "Attributes on lambdas"
    paper: P2173
    summary: "Attributes can be applied to lambda expressions."
    support:
      - GCC 9
      - Clang 13
      - MSVC 14.44
      - Xcode 13.4.1

  - desc: "`std::expected` (`<expected>`)"
    paper: [P0323, P2549]
    content: expected.md
    lib: true
    support:
      - GCC 12
      - Clang 16
      - MSVC 14.33
      - Xcode 15
    ftm:
      - name: __cpp_lib_expected
        value: 202202L

  - desc: "`constexpr` for `<cmath>` and `<cstdlib>`"
    paper: P0533
    lib: true
    ftm:
      - name: __cpp_lib_constexpr_cmath
        value: 202202L

  - desc: "`std::unreachable()`"
    paper: P0627
    lib: true
    support:
      - GCC 12
      - Clang 15
      - MSVC 14.32
      - Xcode 14.3
    ftm:
      - name: __cpp_lib_unreachable
        value: 202202L

  - desc: "Conversions from ranges to containers (`ranges::to()`)"
    paper: P1206
    content: ranges-to.md
    lib: true
    support:
      - GCC 14 (partial)
      - GCC 15
      - Clang 17
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_containers_ranges
        value: 202202L
      - name: __cpp_lib_ranges_to_container
        value: 202202L

  - desc: "Deprecating `std::aligned_storage` and `std::aligned_union`"
    paper: P1413
    lib: true
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.33
      - Xcode 16.1

  - desc: "`std::reference_constructs_from_temporary` and `std::reference_converts_from_temporary`"
    paper: P2255
    lib: true
    support:
      - GCC 13 (partial)
      - GCC 14
      - Clang 21 (partial)
      - MSVC 14.51
      - Xcode 16.3
    hints:
      - target: GCC 13
        msg: "Missing changes to `std::tuple`."
      - target: Clang 21
        msg: "Only type traits are implemented."
    ftm:
      - name: __cpp_lib_reference_from_temporary
        value: 202202L

  - desc: "`constexpr` `std::unique_ptr`"
    paper: P2273
    lib: true
    support:
      - GCC 12
      - Clang 16
      - MSVC 14.33
      - Xcode 15
    ftm:
      - name: __cpp_lib_constexpr_memory
        value: 202202L

  - desc: "Pipe support for user-defined range adaptors (`ranges::range_adaptor_closure` and `std::bind_back()`)"
    paper: P2387
    lib: true
    support:
      - GCC 13 (partial)
      - GCC 14
      - Clang 19
      - MSVC 14.34
      - Xcode 16.3
    ftm:
      - name: __cpp_lib_bind_back
        value: 202202L
      - name: __cpp_lib_ranges
        value: 202202L

  - desc: "`ranges::iota()`, `ranges::shift_left()` and `ranges::shift_right()`"
    paper: P2440
    lib: true
    support:
      - GCC 13 (partial)
      - MSVC 14.34
      - Clang 21 (partial)
      - Clang 22 (partial)
      - Clang 23
    hints:
      - target: GCC 13
        msg: "Only `ranges::iota()` is implemented."
      - target: Clang 21
        msg: "Only `ranges::iota()` is implemented. ([GitHub PR](https://github.com/llvm/llvm-project/pull/68494))"
      - target: Clang 22
        msg: "In addition to Clang 21, supports `ranges::shift_left()` and defines the `__cpp_lib_shift` FTM."
    ftm:
      - name: __cpp_lib_ranges_iota
        value: 202202L
      - name: __cpp_lib_shift
        value: 202202L

  - desc: "`views::join_with()`"
    paper: P2441
    lib: true
    support:
      - GCC 13
      - Clang 21
      - MSVC 14.34
    ftm:
      - name: __cpp_lib_ranges_join_with
        value: 202202L

  - desc: "`views::chunk()` and `views::slide()`"
    paper: P2442
    lib: true
    support: [GCC 13, MSVC 14.33]
    ftm:
      - name: __cpp_lib_ranges_chunk
        value: 202202L
      - name: __cpp_lib_ranges_slide
        value: 202202L

  - desc: "`views::chunk_by()`"
    paper: P2443
    lib: true
    support:
      - GCC 13
      - Clang 18
      - MSVC 14.33
      - Xcode 16
    ftm:
      - name: __cpp_lib_ranges_chunk_by
        value: 202202L

  - desc: "The equality operator you are looking for"
    paper: P2468
    support:
      - GCC 13
      - Clang 16
      - Xcode 16
      - MSVC 14.36

  - desc: "De-deprecating volatile compound operations."
    paper: P2327
    lib: true
    support: [Xcode 15, MSVC 14.34]

  - desc: "`#warning`"
    paper: P2437
    summary: "Standard preprocessor directive to emit compiler warnings."
    support:
      - GCC 13
      - Clang
      - MSVC 14.50
      - Xcode 15

  - desc: "Remove non-encodable wide character literals and multicharacter wide character literals"
    paper: P2362
    support:
      - GCC 13
      - Clang 14
      - Xcode 15

  - desc: "Labels at the end of compound statements"
    paper: P2324
    summary: "Labels can appear at the end of blocks, without a following statement."
    support:
      - GCC 13
      - Clang 16
      - Xcode 16

  - desc: "Delimited escape sequences"
    paper: P2290
    summary: "New `\\x{...}`, `\\o{...}`, and `\\u{...}` syntax for escape sequences."
    support:
      - GCC 13
      - Clang 15
      - MSVC 14.50
      - Xcode 15

  - desc: "Relaxing some `constexpr` restrictions"
    paper: P2448
    summary: "Fewer requirements for constexpr functions."
    support:
      - GCC 13
      - Clang 19
      - Xcode 16.3
    ftm:
      - name: __cpp_constexpr
        value: 202207L

  - desc: "Simpler implicit move"
    paper: P2266
    summary: "Simplified rules for when return statements implicitly move."
    support:
      - GCC 13
      - Clang 13
      - Xcode 26
      - MSVC 14.50
    ftm:
      - name: __cpp_implicit_move
        value: 202207L

  - desc: "Named universal character escapes"
    paper: P2071
    summary: "Use Unicode character names in string literals."
    support:
      - GCC 13
      - Clang 15
      - Xcode 15
    ftm:
      - name: __cpp_named_character_escapes
        value: 202207L

  - desc: "`static operator()` (static call operator)"
    paper: P1169
    summary: "Call operators can now be static."
    content: static-call-operator.md
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.44
      - Xcode 16
    ftm:
      - name: __cpp_static_call_operator
        value: 202207L

  - desc: "Deduction guides update for `static operator()`"
    paper: P1169
    lib: true
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.39
      - Xcode 15

  - desc: "Using unknown pointers and references in constant expressions"
    paper: P2280
    support:
      - GCC 14
      - Clang 20
      - MSVC 14.50
    keywords: ["constexpr"]

  - desc: "Requirements for optional extended floating-point types"
    paper: P1467
    support: [GCC 13, MSVC (hint)]
    hints:
      - target: MSVC
        msg: "Not applicable to MSVC."

  - desc: "Standard names and library support for extended floating-point types"
    paper: P1467
    lib: true
    support: [GCC 13, MSVC 14.37]

  - desc: "Adjusting the value of feature-test macro `__cpp_concepts`"
    paper: P2493
    support:
      - GCC 12
      - Clang 19
      - MSVC 14.50
      - Xcode 16.4

  - desc: "Class template argument deduction from inherited constructors"
    paper: P2582
    summary: "Class template argument deduction works with inherited constructors."
    support: [GCC 14]

  - desc: "Attribute `[[assume]]`"
    paper: P1774
    summary: "Tell the compiler that a condition is always true."
    support:
      - GCC 13
      - Clang 19
      - Xcode 16.3

  - desc: "Support for UTF-8 as a portable source file encoding"
    paper: P2295
    support:
      - GCC 13
      - Clang 15
      - MSVC 14.0
      - Xcode 15

  - desc: "`char8_t` compatibility and portability fix"
    paper: P2513
    content: char8-t-compatibility.md
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.34
      - Xcode 16
    ftm:
      - name: __cpp_char8_t
        value: 202207L

  - desc: "Relax requirements on `wchar_t` to match existing practices"
    paper: P2460
    support:
      - GCC
      - Clang
      - MSVC 14.44
      - Xcode 15

  - desc: "`std::mdspan`: a non-owning multidimensional array reference (`<mdspan>`)"
    paper: [P0009, P2599, P2604, P2613, P2763]
    content: mdspan.md
    lib: true
    support:
      - GCC 16
      - Clang 18
      - MSVC 14.39
      - Xcode 15
    ftm:
      - name: __cpp_lib_mdspan
        value: 202207L

  - desc: "Revising the wording of stream input operations"
    paper: P1264
    lib: true
    support:
      - GCC ?
      - Clang 9
      - MSVC
      - Xcode 12

  - desc: "`std::flat_map` (`<flat_map>`)"
    paper: P0429
    content: flat-map.md
    lib: true
    support:
      - GCC 15
      - Clang 20
      - MSVC 14.51
      - Xcode 26
    ftm:
      - name: __cpp_lib_flat_map
        value: 202207L

  - desc: "`std::flat_set` (`<flat_set>`)"
    paper: P1222
    lib: true
    support:
      - GCC 15
      - Clang 21
      - MSVC 14.51
    ftm:
      - name: __cpp_lib_flat_set
        value: 202207L

  - desc: "`ranges::find_last()`, `ranges::find_last_if()` and `ranges::find_last_if_not()`"
    paper: P1223
    lib: true
    support:
      - GCC 13
      - Clang 19
      - MSVC 14.36
      - Xcode 16.3
    ftm:
      - name: __cpp_lib_ranges_find_last
        value: 202207L

  - desc: "Freestanding library: Easy `<utility>`, `<ranges>` and `<iterator>`"
    paper: P1642
    lib: true
    support: [GCC 13, MSVC 14.38]

  - desc: "`ranges::stride_view` and `views::stride()`"
    paper: P1899
    lib: true
    support: [GCC 13, MSVC 14.34]
    ftm:
      - name: __cpp_lib_ranges_stride
        value: 202207L

  - desc: "Formatted output library (`<print>`, `std::print()`, `std::println()`)"
    paper: [P2093, P2539]
    content: print.md
    lib: true
    support:
      - GCC 14
      - Clang 17 (partial)
      - Clang 18
      - MSVC 14.37
      - Xcode 15 (partial)
      - Xcode 16
    hints:
      - target: Clang 17
        msg: "Overloads for `std::ostream` are not implemented."
      - target: Xcode 15
        msg: "Overloads for `std::ostream` are not implemented."
    ftm:
      - name: __cpp_lib_print
        value: 202207L

  - desc: "Compatibility between `std::tuple` and tuple-like objects"
    paper: P2165
    lib: true
    support:
      - GCC 14 (partial)
      - GCC 16
      - Clang 2.9 (partial)
      - MSVC 14.36 (partial)
      - MSVC 14.37
      - Xcode (partial)
    hints:
      - target: GCC 14
        msg: "Some views incorrectly still return `std::pair` instead of `std::tuple`"
      - target: Clang 2.9
        msg: "Changes of `tuple`, `adjacent_view`, and `cartesian_product_view` are not yet implemented."
      - target: MSVC 14.36
        msg: "Implemented for `std::pair`."
      - target: Xcode
        msg: "Only the part for `zip_view` is implemented."
    ftm:
      - name: __cpp_lib_tuple_like
        value: 202207L

  - desc: "Rectifying constant iterators, sentinels and ranges (`views::as_const()`)"
    paper: P2278
    lib: true
    support:
      - GCC 13
      - MSVC 14.35 (partial)
      - MSVC 14.36
    hints:
      - target: MSVC 14.35
        msg: "The \\\"Iterators\\\" section, including `basic_const_iterator`, `make_const_iterator()`, and `make_const_sentinel()`."
    ftm:
      - name: __cpp_lib_ranges_as_const
        value: 202207L

  - desc: "Formatting ranges"
    paper: P2286
    lib: true
    support:
      - GCC 15 (partial)
      - GCC 15.2
      - Clang 16
      - MSVC 14.37 (partial)
      - MSVC 14.39 (partial)
      - MSVC 14.41 (partial)
      - MSVC 14.42
      - Xcode 15
    hints:
      - target: GCC 15
        msg: "Missing formatter specializations for `queue`, `stack`, and `priority_queue`."
      - target: MSVC 14.37
        msg: "2022.7: Implemented the `?` format specifier for strings and characters."
      - target: MSVC 14.39
        msg: "2022.9: Implemented `formatter::set_debug_format()`, `formattable`, `range_format`, and `format_kind`."
      - target: MSVC 14.41
        msg: "2022.11: Implemented formatter for `std::pair` and `std::tuple`. Also `range_formatter`."
    ftm:
      - name: __cpp_lib_format_ranges
        value: 202207L

  - desc: "`constexpr` for integral overloads of `std::to_chars()` and `std::from_chars()`"
    paper: P2291
    lib: true
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_constexpr_charconv
        value: 202207L

  - desc: "`ranges::contains()` and `ranges::contains_subrange()`"
    paper: P2302
    lib: true
    support:
      - GCC 13
      - Clang 18 (partial)
      - Clang 19
      - MSVC 14.34
      - Xcode 16 (partial)
      - Xcode 16.3
    hints:
      - target: Clang 18
        msg: "`ranges::contains_subrange()` is not implemented."
      - target: Xcode 16
        msg: "`ranges::contains_subrange()` is not implemented."
    ftm:
      - name: __cpp_lib_ranges_contains
        value: 202207L

  - desc: "Ranges fold algorithms (`ranges::fold()`)"
    paper: P2322
    lib: true
    support: [GCC 13, MSVC 14.35]
    ftm:
      - name: __cpp_lib_ranges_fold
        value: 202207L

  - desc: "`views::cartesian_product()`"
    paper: [P2374, P2540]
    lib: true
    support: [GCC 13, MSVC 14.37]
    ftm:
      - name: __cpp_lib_ranges_cartesian_product
        value: 202207L

  - desc: "Adding move-only types support for comparison concepts (`std::equality_comparable`, `std::totally_ordered`, `std::three_way_comparable`)"
    paper: P2404
    lib: true
    support:
      - GCC 16
      - Clang 22 (hint)
      - MSVC 14.36
    hints:
      - target: Clang 22
        msg: "Implemented as a defect report (DR) for C++20."
    ftm:
      - name: __cpp_lib_concepts
        value: 202207L

  - desc: "Ranges iterators as inputs to non-ranges algorithms"
    paper: P2408
    lib: true
    support: [GCC 16, MSVC 14.34]
    ftm:
      - name: __cpp_lib_algorithm_iterator_requirements
        value: 202207L

  - desc: "`constexpr` `std::bitset`"
    paper: P2417
    lib: true
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_constexpr_bitset
        value: 202207L

  - desc: "Clarify handling of encodings in localized formatting of chrono types"
    paper: P2419
    lib: true
    support: [GCC 15, MSVC 14.34]
    ftm:
      - name: __cpp_lib_format
        value: 202207L

  - desc: "`std::basic_string::substr()` `&&`"
    paper: P2438
    lib: true
    support:
      - Clang 16
      - MSVC 14.34
      - Xcode 15

  - desc: "`views::as_rvalue()`"
    paper: P2446
    lib: true
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_ranges_as_rvalue
        value: 202207L

  - desc: "Standard library modules (`import std`)"
    paper: P2465
    lib: true
    support:
      - GCC 15 (hint)
      - Clang 17 (partial)
      - Clang 19
      - MSVC 14.35 (partial)
      - MSVC 14.36
    hints:
      - target: GCC 15
        msg: "Requires enabling compiler flag `-fmodules` to enable experimental modules support."
      - target: Clang 17
        msg: "Experimental support only."
      - target: MSVC 14.35
        msg: "Modules work, but you have to manually add them to your Visual Studio project."
    ftm:
      - name: __cpp_lib_modules
        value: 202207L

  - desc: "`std::forward_like()`"
    paper: P2445
    lib: true
    support:
      - GCC 14
      - Clang 16
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_forward_like
        value: 202207L

  - desc: "Support exclusive mode for `std::fstream`"
    paper: P2467
    lib: true
    support:
      - GCC 12
      - Clang 18
      - MSVC 14.36
      - Xcode 16
    ftm:
      - name: __cpp_lib_ios_noreplace
        value: 202207L

  - desc: "`views::repeat()`"
    paper: P2474
    lib: true
    support:
      - GCC 13
      - Clang 17
      - MSVC 14.36
      - Xcode 15
    ftm:
      - name: __cpp_lib_ranges_repeat
        value: 202207L

  - desc: "Relaxing range adaptors to allow for move-only types"
    paper: P2494
    lib: true
    support:
      - GCC 14
      - Clang 17
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_ranges
        value: 202207L

  - desc: "`std::basic_string_view` range constructor should be `explicit`"
    paper: P2499
    lib: true
    support:
      - GCC 12.2
      - Clang 16
      - MSVC 14.34
      - Xcode 15

  - desc: "`std::generator`: synchronous coroutine generator for ranges"
    paper: [P2502, P2787]
    content: generator.md
    lib: true
    support: [GCC 14, MSVC 14.43]
    ftm:
      - name: __cpp_lib_generator
        value: 202207L

  - desc: "`std::basic_format_string`"
    paper: P2508
    lib: true
    support:
      - GCC 13
      - Clang 15
      - MSVC 14.35
      - Xcode 14.3

  - desc: "Add a conditional `noexcept` specification to `std::apply()`"
    paper: P2517
    lib: true
    support:
      - GCC 10
      - Clang 18
      - MSVC 14.34
      - Xcode 16

  - desc: "`std::move_iterator<T*>` should be a random access iterator"
    paper: P2520
    lib: true
    support:
      - GCC 12.3
      - Clang 17
      - MSVC 14.34
      - Xcode 15
    ftm:
      - name: __cpp_lib_move_iterator_concept
        value: 202207L

  - desc: "Improve default container formatting"
    paper: P2585
    lib: true
    support:
      - GCC 15
      - Clang 16 (partial)
      - Clang 17
      - Xcode 15
      - MSVC 14.42
    hints:
      - target: Clang 16
        msg: "Specializations for string and debug_string are not done."
    ftm:
      - name: __cpp_lib_format_ranges
        value: 202207L

  - desc: "Explicit lifetime management (`std::start_lifetime_as()`)"
    paper: [P2590, P2679]
    lib: true
    support: [GCC 16]
    ftm:
      - name: __cpp_lib_start_lifetime_as
        value: 202207L

  - desc: "`static operator[]`"
    paper: P2589
    content: static-subscript-operator.md
    support:
      - GCC 13
      - Clang 16
      - MSVC 14.44
      - Xcode 16
    ftm:
      - name: __cpp_multidimensional_subscript
        value: 202211L

  - desc: "Permitting static `constexpr` variables in `constexpr` functions"
    paper: P2647
    support:
      - GCC 13
      - Clang 16
      - Xcode 16
    ftm:
      - name: __cpp_constexpr
        value: 202211L

  - desc: "`consteval` needs to propagate up"
    paper: P2564
    summary: "consteval calls in default arguments work correctly."
    support:
      - GCC 14
      - Clang 17
      - Xcode 16
    ftm:
      - name: __cpp_consteval
        value: 202211L

  - desc: "Meaningful exports"
    paper: P2615
    support:
      - GCC 15
      - Clang 17
      - MSVC 14.28

  - desc: "Extending the lifetime of temporaries in range-based `for` loop initializer"
    paper: [P2644, P2718]
    support:
      - GCC 15
      - Clang 19 (partial)
      - Clang 20
      - Xcode 16.3
    hints:
      - target: Clang 19
        msg: "Misses lifetime extension of temporaries in `mem-default-init` cases."
    ftm:
      - name: __cpp_range_based_for
        value: 202211L
    keywords: ["safety"]

  - desc: "Poison Pills are Too Toxic"
    paper: P2602
    lib: true
    support:
      - GCC 14
      - Clang 19
      - MSVC 14.36
      - Xcode 16.3
    ftm:
      - name: __cpp_lib_ranges
        value: 202211L

  - desc: "Monadic operations for `std::expected` (`and_then()`, `or_else()`, `transform()`)"
    paper: P2505
    lib: true
    support:
      - GCC 13
      - Clang 17
      - MSVC 14.36
      - Xcode 15
    ftm:
      - name: __cpp_lib_expected
        value: 202211L

  - desc: "Referencing the Unicode Standard"
    paper: P2736
    lib: true
    support:
      - GCC
      - Clang
      - Xcode
      - MSVC 14.37

  - desc: "Proposed resolution for [CWG2692](https://wg21.link/CWG2692) static and explicit object member functions with the same parameter-type-lists"
    paper: P2797
    support:
      - GCC 14
      - Clang 19
      - MSVC 14.50
      - Xcode 16.3

  - desc: "Stashing stashing iterators for proper flattening"
    paper: P2770
    lib: true
    support:
      - GCC 14
      - Clang 21
      - MSVC 14.37

  - desc: "`views::enumerate()`"
    paper: P2164
    content: enumerate.md
    lib: true
    support: [GCC 13, MSVC 14.37]
    ftm:
      - name: __cpp_lib_ranges_enumerate
        value: 202302L

  - desc: "Making multi-param constructors of views explicit"
    paper: P2711
    lib: true
    support:
      - GCC 16
      - Clang 17 (partial)
      - Clang 21
      - MSVC 14.36 (hint)
      - Xcode 15
    hints:
      - target: Clang 17
        msg: "`join_with_view` has not been done yet since this type is not implemented yet."
      - target: MSVC 14.36
        msg: "Treated as a defect report against C++20."

  - desc: "Relaxing Ranges Just A Smidge"
    paper: P2609
    lib: true
    support:
      - GCC 15
      - Clang 20
      - MSVC 14.37
      - Xcode 26
    ftm:
      - name: __cpp_lib_ranges
        value: 202302L

  - desc: "Escaping improvements in `std::format()`"
    paper: P2713
    lib: true
    support:
      - GCC 15
      - Clang 19
      - MSVC 14.37
      - Xcode 16.4

  - desc: "Improving `std::format()`'s width estimation"
    paper: P2675
    lib: true
    support:
      - GCC 14
      - Clang 17
      - MSVC 14.38
      - Xcode 16.1

  - desc: "`std::format()` fill character allowances"
    paper: P2572
    lib: true
    support:
      - GCC 14
      - Clang 17
      - MSVC 14.37

  - desc: "Formatting `std::thread::id` and `std::stacktrace`"
    paper: P2693
    lib: true
    support:
      - GCC 14
      - Clang 17 (partial)
      - MSVC 14.38
      - Xcode 15
    hints:
      - target: Clang 17
        msg: "`std::stacktrace` is not implemented yet."
    ftm:
      - name: __cpp_lib_formatters
        value: 202302L

  - desc: "A trait for implicit lifetime types (`std::is_implicit_lifetime`)"
    paper: P2674
    lib: true
    support:
      - GCC 16
      - Clang 20
      - MSVC 14.51
      - Xcode 26
    ftm:
      - name: __cpp_lib_is_implicit_lifetime
        value: 202302L

  - desc: "`std::common_reference_t` of `std::reference_wrapper` should be a reference type"
    paper: P2655
    lib: true
    support:
      - GCC 16
      - Clang 21 (hint)
      - MSVC 14.37
    hints:
      - target: Clang 21
        msg: "The feature is implemented as a defect report to C++20."
    ftm:
      - name: __cpp_lib_common_reference
        value: 202302L
      - name: __cpp_lib_common_reference_wrapper
        value: 202302L

  - desc: "Disallowing user specialization of `std::allocator_traits`"
    paper: P2652
    lib: true
    support: [Clang 19, MSVC 14.37]

  - desc: "Deprecating `std::numeric_limits::has_denorm`"
    paper: P2614
    lib: true
    support:
      - Clang 18
      - MSVC 14.37
      - Xcode 16

  - desc: "`std::barrier`'s phase completion guarantees"
    paper: P2588
    lib: true
    support: [MSVC 14.28 (hint), MSVC 14.36]
    hints:
      - target: MSVC 14.28
        msg: "Implemented, but no feature-testing macro is available."
    ftm:
      - name: __cpp_lib_barrier
        value: 202302L

  - desc: "Declarations and where to find them"
    paper: P1787
    support: [MSVC]