features_c23.yaml

---
features:
  - desc: "`static_assert` with no message"
    paper: N2265
    support:
      - GCC 9
      - Clang 9
      - MSVC
      - Xcode 11.4
  - desc: "`[[nodiscard]]`"
    paper: N2267
    summary: "Marks a return value that should not be ignored."
    support:
      - GCC 10
      - Clang 9
      - Xcode 11.4
    content: c-nodiscard.md
  - desc: "`[[maybe_unused]]`"
    paper: N2270
    support:
      - GCC 10
      - Clang 9
      - Xcode 11.4
  - desc: "`[[deprecated]]`"
    paper: N2334
    support:
      - GCC 10
      - Clang 9
      - Xcode 11.4
  - desc: "[Attributes](https://cppreference.com/c/language/attributes)"
    paper:
      - N2335
      - N2554
    content: c-attributes.md
    support:
      - GCC 10
      - Clang 9
      - Xcode 11.4
  - desc: "IEEE 754 decimal floating-point types"
    paper: N2341
    support:
      - GCC 4.2 (partial)
      - GCC 12
  - desc: "`[[fallthrough]]`"
    paper: N2408
    support:
      - GCC 10
      - Clang 9
      - Xcode 11.4
  - desc: "[u8 character constants](https://cppreference.com/c/language/character_constant)"
    paper: N2418
    support:
      - GCC 10
      - Clang 15
      - Xcode 15
  - desc: "Removal of [function definitions](https://cppreference.com/c/language/function_definition) without prototype"
    paper: N2432
    support:
      - GCC 10
      - Clang 15
      - Xcode 16.1
  - desc: "`[[nodiscard]]` with message"
    paper: N2448
    support:
      - GCC 11
      - Clang 10
      - Xcode 14
  - desc: "Unnamed parameters in function definitions"
    paper: N2480
    support:
      - GCC 11
      - Clang 11
      - Xcode 13
  - desc: "[Labels](https://cppreference.com/c/language/statements#Labels) before declarations and end of blocks"
    paper: N2508
    support:
      - GCC 11
      - Clang 16 (partial)
      - Clang 18
      - MSVC (partial)
      - Xcode 15
    hints:
      - target: Clang 16
        msg: "Only labels at the end of a block are supported"
  - desc: "[Binary integer constants](https://cppreference.com/c/language/integer_constant)"
    paper: N2549
    content: c-binary-literals.md
    support:
      - GCC 4.3 (hint)
      - GCC 11
      - Clang 2.9 (hint)
      - Clang 9
      - MSVC 14.0 (hint)
      - Xcode 7 (hint)
      - Xcode 16.3
      - owcc
      - TinyCC
    hints:
      - target: GCC 4.3
        msg: "Supported as an extension."
      - target: Clang 2.9
        msg: "Supported as an extension."
      - target: MSVC 14.0
        msg: "Supported as an extension."
      - target: Xcode 7
        msg: "Supported as an extension."
  - desc: "[__has_c_attribute](https://cppreference.com/c/language/attributes#Attribute_testing) in preprocessor conditionals"
    paper: N2553
    support:
      - GCC 11
      - Clang 9
      - Xcode 11.4
  - desc: "Allow duplicate attributes"
    paper: N2557
    support:
      - GCC 11
      - Clang 13
      - Xcode 11.4
  - desc: "IEEE 754 interchange and extended types"
    paper: N2601
    support:
      - GCC 7 (partial)
      - GCC 14
      - Clang 6 (partial)
      - Xcode (partial)
    hints:
      - target: GCC 7
        msg: "Only TS 18661-3 mentioned; the status of conformance is unknown."
      - target: Clang 6
        msg: "Only `_Float16` is supported."
      - target: Xcode
        msg: "Only `_Float16` is supported."
  - desc: "Compatibility of Pointers to Arrays with Qualifiers"
    paper: N2607
    support:
      - GCC 5
      - Clang 3
  - desc: "Digit separators"
    paper: N2626
    content: c-digit-separators.md
    support:
      - GCC 12
      - Clang 13
      - MSVC 14.0 (hint)
      - Xcode 13.4
    hints:
      - target: MSVC 14.0
        msg: "Supported as an extension."
  - desc: "[`#elifdef` and `#elifndef`](https://cppreference.com/c/preprocessor/conditional)"
    paper: N2645
    content: c-elifdef.md
    support:
      - GCC 12
      - Clang 13
      - MSVC 14.40
      - Xcode 13.3
  - desc: "Type change of [u8 string literals](https://cppreference.com/c/language/string_literal) to `char8_t[]`"
    paper: N2653
    support:
      - GCC 13
      - Clang 19
  - desc: "`[[maybe_unused]]` for labels"
    paper: N2662
    support:
      - GCC 11
      - Clang 16
      - Xcode 16.1
  - desc: "`#warning`"
    paper: N2686
    support:
      - GCC
      - Clang
      - Xcode 16.1
      - owcc
      - TinyCC
  - desc: "Bit-precise integer types (`_BitInt`)"
    paper: N2763
    content: c-bitint.md
    support:
      - GCC 14 (partial)
      - Clang 15
      - Xcode 15
    hints:
      - target: GCC 14
        msg: "Only supported on IA-32, x86-64 and AArch64 LE."
  - desc: "`[[noreturn]]`"
    paper: N2764
    support:
      - GCC 13
      - Clang 15
      - Xcode 15
  - desc: "Suffixes for bit-precise integer constants"
    paper: N2775
    support:
      - GCC 14
      - Clang 15
      - Xcode 16.1
  - desc: "Require support for variably modified types"
    paper: N2778
    support:
      - GCC
      - Clang
      - Xcode
      - TinyCC 0.9.28
  - desc: "`__has_include` in preprocessor conditionals"
    paper: N2799
    support:
      - GCC 5
      - Clang
      - MSVC 14.11
      - Xcode
      - TinyCC
  - desc: "Identifier Syntax using Unicode Standard Annex 31"
    paper: N2836
    support:
      - GCC 13
      - Clang 15
      - Xcode 16.1
  - desc: "Removal of [function declarations](https://cppreference.com/c/language/function_declaration) without prototype"
    paper: N2841
    support:
      - GCC 13
      - Clang 15
      - Xcode 16.1
  - desc: "[Empty initializers](https://cppreference.com/c/language/initialization#Empty_initialization)"
    paper: N2900
    content: c-empty-init.md
    support:
      - GCC 13 (hint)
      - Clang 17 (hint)
      - Xcode (partial)
    hints:
      - target: GCC 13
        msg: "Partially supported as an extension before."
      - target: Clang 17
        msg: "Supported as an extension before without support for scalars and variable-length arrays (VLAs)."
      - target: Xcode
        msg: "Supported as an extension. Missing support for scalars and variable-length arrays (VLAs)."
  - desc: "`typeof` and `typeof_unqual`"
    paper:
      - N2927
      - N2930
    content: c-typeof.md
    support:
      - GCC 13 (hint)
      - Clang 16 (hint)
      - MSVC 14.39
      - Xcode (partial)
    hints:
      - target: GCC 13
        msg: "Prior to GCC 13: Supported as an extension. Only typeof (and `__typeof__` in strict modes) supported."
      - target: Clang 16
        msg: "Prior to Clang 16: Supported as an extension. Only typeof (and `__typeof__` in strict modes) supported."
      - target: Xcode
        msg: "Supported as an extension. Only typeof (and `__typeof__` in strict modes) supported."
  - desc: "New spelling of keywords"
    paper: N2934
    support:
      - GCC 13
      - Clang 16 (partial)
      - Xcode 16.1
  - desc: "Predefined `true` and `false`"
    paper: N2935
    content: c-bool-true-false.md
    support:
      - GCC 13
      - Clang 15
      - Xcode 16.1
  - desc: "`[[unsequenced]]` and `[[reproducible]]`"
    paper: N2956
    content: c-unreachable.md
    support:
      - GCC 15
  - desc: "Relax requirements for [variadic parameter list](https://cppreference.com/c/language/variadic)"
    paper: N2975
    support:
      - GCC 13
      - Clang 16
      - Xcode 16.1
  - desc: "Type inference in object definitions (`auto`)"
    paper: N3007
    content: c-auto.md
    support:
      - GCC 13
      - Clang 18
      - Xcode 16.4
  - desc: "`#embed`"
    paper: N3017
    content: c-embed.md
    support:
      - GCC 15
      - Clang 19
      - Xcode 26
  - desc: "`constexpr` objects"
    paper: N3018
    content: c-constexpr.md
    support:
      - GCC 13
      - Clang 19
      - Xcode 16.4
  - desc: "Improved Normal Enumerations"
    paper: N3029
    support:
      - GCC 13
      - Clang 20 (hint)
      - Xcode 16.1
    hints:
      - target: Clang 20
        msg: "Supported as an extension with incomplete diagnostics in earlier versions."
  - desc: "Enumerations with fixed underlying types"
    paper: N3030
    content: c-fixed-enum.md
    support:
      - GCC 13
      - Clang 20 (hint)
      - Xcode 16.1
    hints:
      - target: Clang 20
        msg: "Supported as an extension with incomplete diagnostics in earlier versions."
  - desc: "`__VA_OPT__`"
    paper: N3033
    content: c-va-opt.md
    support:
      - GCC 8
      - GCC 13
      - Clang 12 (partial)
      - MSVC 14.39
      - Xcode 14
  - desc: "Improved tag compatibility"
    paper: N3037
    support:
      - GCC 14
      - Clang 21 (partial)
  - desc: "Storage-class specifiers for compound literals"
    paper: N3038
    support:
      - GCC 13
  - desc: "`nullptr`"
    paper: N3042
    content: c-nullptr.md
    support:
      - GCC 13
      - Clang 16 (partial)
      - Xcode 16.1
  - desc: "Partial program correctness"
    paper: N3128
    support:
      - GCC (partial)
    hints:
      - target: GCC
        msg: "Not guaranteed for volatile accesses"