Difference between revisions of "c/23"

Latest revision as of 21:39, 9 February 2024

The next generation of the C standard.

The latest publicly available WD of C23 (n3301, 2024-07-28).
The latest WD of C23 (n3149, 2023-07-09, a password-protected zip archive, see n3150).

[edit] Obsolete

[edit] Removed

Old-style function declarations and definitions
Representations for signed integers other than two's complement
Permission that u/U-prefixed character constants and string literals may be not UTF-16/32
Mixed wide string literal concatenation
Support for calling realloc() with zero size (the behavior becomes undefined)
__alignof_is_defined and __alignas_is_defined
static_assert is not provided as a macro defined in <assert.h> (becomes a keyword)
thread_local is not provided as a macro defined in <threads.h> (becomes a keyword)

[edit] Deprecated

<stdnoreturn.h>
Old feature-test macros
- __STDC_IEC_559__
- __STDC_IEC_559_COMPLEX__
_Noreturn function specifier
_Noreturn attribute token
asctime()
ctime()
DECIMAL_DIG (use the appropriate type-specific macro (FLT_DECIMAL_DIG, etc) instead)
Definition of following numeric limit macros in <math.h> (they should be used via <float.h>)
__bool_true_false_are_defined

[edit] New language features

Decimal floating-point types (_Decimal32, _Decimal64, and _Decimal128)
Bit-precise integers (_BitInt)
Binary integer constants
u8 character constants
Type change of u8 string literals
Digit separator '
Empty initializer ={}
Attributes
- [[deprecated]]
- [[fallthrough]]
- [[maybe_unused]]
- [[nodiscard]]
- [[noreturn]]
- [[reproducible]]
- [[unsequenced]]
Unnamed parameters in function definitions
Identical cvr-qualifications for array types and their element types
Single-argument _Static_assert
static_assert becomes a keyword (may be a predefined macro for compatibility reasons)
thread_local becomes a keyword (may be a predefined macro for compatibility reasons)
Labels followed by declarations and }
nullptr constant and the associated nullptr_t type
true and false become keywords (may be predefined macros for compatibility reasons)
New preprocessor directives
Pragmas for rounding direction
- STDC FENV_ROUND
- STDC FENV_DEC_ROUND

[edit] Feature test macros for optional features

__STDC_IEC_60559_BFP__
- Indicates IEEE-754 binary floating-point arithmetic and required math functions are supported.
This macro supersedes __STDC_IEC_559__.
__STDC_IEC_60559_DFP__
- Indicates IEEE-754 decimal floating-point arithmetic and required math functions are supported.
__STDC_IEC_60559_COMPLEX__
- Indicates IEEE-754 complex arithmetic and required math functions are supported.
This macro supersedes __STDC_IEC_559_COMPLEX__.

[edit] New library features

[edit] New headers

<stdbit.h>
<stdckdint.h>

[edit] Library features

Extended binary floating-point math functions
Decimal floating-point math functions
- -dN variants for existing and new floating-point math functions
- quantizedN()
- samequantumdN()
- quantumdN()
- llquantexpdN()
- encodedecdN()
- decodedecdN()
- encodebindN()
- decodebindN()
Floating-point formatting functions
Library support for UTF-8
- char8_t type alias
- mbrtoc8()
- c8rtomb()
- atomic_char8_t type alias
- ATOMIC_CHAR8_T_LOCK_FREE test macro
memset_explicit()
POSIX functions
- memccpy()
- strdup()
- strndup()
- gmtime_r()
- localtime_r()
- Extensions for strftime() and wcsftime()
Extensions for fscanf() and fprintf() function families
- wN and wfN length modifiers for [u]intN_t and [u]int_fastN_t respectively
- H, D, and DD length modifiers for _Decimal32, _Decimal64, and _Decimal128 respectively
- b conversion specifier for unsigned integer types
timespec_getres()
Macro constants for width of integer types
Additional numeric limit macros for floating-point types
Library version-test macros

[edit] Defect reports

Defect Reports fixed in C23 (? defects)
DR 440 DR 432 DR 467 DR 476 DR 482 DR 488 DR 489 DR 494 DR 496 DR 497 DR 499 DR 500 DR 501

[edit] Compiler support

[edit] C23 core language features

C23 feature	Paper(s)	GCC	Clang	MSVC	Apple Clang	EDG eccp	Intel C++	IBM XL C++	IBM Open XL C++ for AIX	IBM Open XL C++ for z/OS	Sun/Oracle C++	Embarcadero C++ Builder	Cray	Nvidia HPC C++ (ex PGI)*	Nvidia nvcc
`_Static_assert` with no message	N2265	9	9	Yes	Yes	6.5	2021.1.2 (clang based)
`[[nodiscard]]`	N2267	10	9		Yes	6.4	2021.1.2 (clang based)
`[[maybe_unused]]`	N2270	10	9		Yes	6.4	2021.1.2 (clang based)
`[[deprecated]]`	N2334	10	9		Yes	6.4	2021.1.2 (clang based)
Attributes	N2335 N2554	10	9		Yes	6.4	2021.1.2 (clang based)
IEEE 754 decimal floating-point types	N2341	4.2 (partial)* 12					13.0 (partial)*
`[[fallthrough]]`	N2408	10	9		Yes	6.4	2021.1.2 (clang based)
`u8` character constants	N2418	10	15			6.5	2022.2
Removal of function definitions without prototype	N2432	10	15				2022.2
`[[nodiscard]]` with message	N2448	11	10		Yes	6.4	2021.1.2 (clang based)
Unnamed parameters in function definitions	N2480	11	11		Yes	6.4	2021.1.2 (clang based)
Labels before declarations and end of blocks	N2508	11	16	Partial*		6.5	17.0*
Binary integer constants	N2549	4.3* 11	2.9* 9	19.0 (2015)**	Yes	6.5	11.0*
`__has_c_attribute` in preprocessor conditionals	N2553	11	9		Yes	6.5	2021.1.2 (clang based)
Allow duplicate attributes	N2557	11	13		Yes	6.5	2021.4 (clang-based
IEEE 754 interchange and extended types	N2601	7 (partial)* 14	6 (partial)*		Partial*
Digit separators	N2626	12	13	19.0 (2015)**	Yes	6.5	18.0*
`#elifdef` and `#elifndef`	N2645	12	13	19.40*	13.1.6*	6.5	2021.4
Type change of `u8` string literals	N2653	13
`[[maybe_unused]]` for labels	N2662	11	16			6.5	2022.2
`#warning`	N2686	Yes	Yes		Yes	6.5	Yes
Bit-precise integer types (_BitInt)	N2763	14 (partial)*	15			6.5	2022.2
`[[noreturn]]`	N2764	13	15			6.5	2022.2
Suffixes for bit-precise integer constants	N2775	14	15				2022.2
`__has_include` in preprocessor conditionals	N2799	5	Yes	19.11*	Yes	6.5	18.0
Identifier Syntax using Unicode Standard Annex 31	N2836	13	15			6.5	2022.2
Removal of function declarations without prototype	N2841	13	15				2022.2
Empty initializers	N2900	Partial* 13	Partial*		Partial*	Partial*	Partial*
`typeof` and `typeof_unqual`	N2927 N2930	Partial* 13	Partial* 16	19.39*	Partial*	Partial*	Partial*						Partial*
New spelling of keywords	N2934	13	16			6.5
Predefined `true` and `false`	N2935	13	15				2022.2
`[[unsequenced]]` and `[[reproducible]]`	N2956	15
Relax requirements for variadic parameter list	N2975	13	16			6.5	2023.1
Type inference in object definitions	N3007	13	18
`#embed`	N3017	15	19
`constexpr` objects	N3018	13	19
Improved Normal Enumerations	N3029	13	20*
Enumerations with fixed underlying types	N3030	13	20*
`__VA_OPT__`	N3033	8 13	12	19.39*		6.5
Storage-class specifiers for compound literals	N3038	13
`nullptr`	N3042	13	16
C23 feature	Paper(s)	GCC	Clang	MSVC	Apple Clang	EDG eccp	Intel C++	IBM XL C++	IBM Open XL C++ for AIX	IBM Open XL C++ for z/OS	Sun/Oracle C++	Embarcadero C++ Builder	Cray	Nvidia HPC C++ (ex PGI)*	Nvidia nvcc

[edit] C23 library features

@@ Line 4: / Line 4: @@
 The next generation of the C standard.
-See: {{stddoc|n2984|The current IS schedule for C23}}.
+* {{stddoc latest draft|The latest publicly available WD of C23}} ({{stdinfo latest draft docnum}}, {{stdinfo latest draft docdate}}).
+* {{stddoc|N3149.zip|The latest WD of C23}} (n3149, 2023-07-09, a password-protected zip archive, see {{stddoc|n3150.htm|n3150}}).
-{{todo| accepted changes not yet included in the working draft}}
+{{todo|accepted changes not yet included in the working draft}}
-== Obsolete ==
+==Obsolete==
 ===Removed===
 * Old-style function [[c/language/function declaration|declarations]] and [[c/language/function definition|definitions]]
 * Representations for [[c/language/arithmetic types|signed integers]] other than two's complement
-* Permission that {{c|u}}/{{c|U}}-prefixed [[c/language/character_constant|character constants]] and [[c/language/string_literal|string literals]] may be not UTF-16/32
+* Permission that {{c|u}}/{{c|U}}-prefixed {{lt|c/language/character constant}}s and {{lt|c/language/string literal}}s may be not UTF-16/32
 * Mixed wide [[c/language/string literal|string literal]] concatenation
 * Support for calling {{ltf|c/memory/realloc}} with zero size (the behavior becomes undefined)
 * {{ltt|c/types|__alignof_is_defined}} and {{ltt|c/types|__alignas_is_defined}}
+* {{ltt|c/error/static_assert}} is not provided as a macro defined in {{header|assert.h}} (becomes a keyword)
+* {{ltt|c/thread/thread_local}} is not provided as a macro defined in {{header|threads.h}} (becomes a keyword)
 ===Deprecated===
+* {{header|stdnoreturn.h}}
 * Old feature-test macros
 ** {{ltt|c/preprocessor/replace|__STDC_IEC_559__}}
 ** {{ltt|c/preprocessor/replace|__STDC_IEC_559_COMPLEX__}}
-* {{ltt|c/types/limits|DECIMAL_DIG}}
+* {{ltt|c/language/_Noreturn}} function specifier
-* Definition of following numeric limit macros in {{tt|<math.h>}} (they should be used via {{tt|<limits.h>}})
+* {{ltt|c/language/attributes/noreturn|_Noreturn}} attribute token
+* {{lc|asctime()}}
+* {{lc|ctime()}}
+* {{ltt|c/types/limits|DECIMAL_DIG}} (use the appropriate type-specific macro ({{ltt|c/types/limits#Limits of floating-point types|FLT_DECIMAL_DIG}}, etc) instead)
+* Definition of following numeric limit macros in {{header|math.h}} (they should be used via {{header|float.h}})
 ** {{ltt|c/numeric/math|INFINITY}}
 ** {{ltt|c/numeric/math|DEC_INFINITY}}
 ** {{ltt|c/numeric/math|NAN}}
 ** {{ltt|c/numeric/math|DEC_NAN}}
-* {{ltt|c/language/_Noreturn}} function specifier
-* {{ltt|c/language/attributes/noreturn|_Noreturn}} attribute token
 * {{ltt|c/types|__bool_true_false_are_defined}}
-== New language features ==
+==New language features==
 * [[c/language/arithmetic types|Decimal floating-point types]] ({{ltt|c/keyword/_Decimal32}}, {{ltt|c/keyword/_Decimal64}}, and {{ltt|c/keyword/_Decimal128}})
+* [[c/language/arithmetic types|Bit-precise integers]] ({{ltt|c/keyword/_BitInt}})
 * [[c/language/integer constant|Binary integer constants]]
 * [[c/language/character constant|{{tt|u8}} character constants]]
 * Type change of [[c/language/string literal|{{tt|u8}} string literals]]
 * Digit separator {{tt|'}}
-* Empty [[c/language/initialization|initializer]] {{c|1== {} }}
+* Empty [[c/language/initialization|initializer]] {{c|1=={}<!---->}}
 * [[c/language/attributes|Attributes]]
-** {{cattr|deprecated}}
+** {{attr|deprecated}}
-** {{cattr|fallthrough}}
+** {{attr|fallthrough}}
-** {{cattr|maybe_unused}}
+** {{attr|maybe_unused}}
-** {{cattr|nodiscard}}
+** {{attr|nodiscard}}
-* Unnamed parameters in [[c/language/function definition|function definitions]]
+** {{attr|noreturn}}
-* Identical cvr-qualifcations for [[c/language/array|array types]] and their element types
+** {{attr|reproducible}}
+** {{attr|unsequenced}}
+* Unnamed parameters in {{lt|c/language/function definition}}s
+* Identical cvr-qualifications for [[c/language/array|array types]] and their element types
 * Single-argument {{ltt|c/language/_Static_assert}}
+* {{ltt|c/keyword/static_assert}} becomes a keyword (may be a predefined macro for compatibility reasons)
+* {{ltt|c/keyword/thread_local}} becomes a keyword (may be a predefined macro for compatibility reasons)
 * [[c/language/goto|Labels]] followed by declarations and {{ttb|}<nowiki/>}}
+* {{ltt|c/keyword/nullptr}} constant and the associated {{ltt|c/types/nullptr_t}} type
+* {{ltt|c/keyword/true}} and {{ltt|c/keyword/false}} become keywords (may be predefined macros for compatibility reasons)
 * New preprocessor directives
 ** {{ltt|c/preprocessor/conditional|#elifdef}}
 ** {{ltt|c/preprocessor/conditional|#elifndef}}
-** {{ltt|c/preprocessor/warning|#warning}}
+** {{ltt|c/preprocessor/error|#warning}}
+** {{ltt|c/preprocessor/embed|#embed}}
 * Pragmas for rounding direction
 ** {{tt|STDC}} {{ltt|c/preprocessor/impl|FENV_ROUND}}
@@ Line 66: / Line 81: @@
 *: This macro supersedes {{ltt|c/preprocessor/replace|__STDC_IEC_559_COMPLEX__}}.
-== New library features ==
+==New library features==
+===New headers===
+* {{header|stdbit.h}}
+* {{header|stdckdint.h}}
+===Library features===
 * Extended binary floating-point math functions
 ** {{todo|List TBD}}
@@ Line 84: / Line 105: @@
 ** {{ltf|c/string/multibyte/mbrtoc8}}
 ** {{ltf|c/string/multibyte/c8rtomb}}
+** {{ltt|c/thread|atomic_char8_t}} type alias
+** {{ltt|c/atomic/ATOMIC_LOCK_FREE_consts|ATOMIC_CHAR8_T_LOCK_FREE}} test macro
+* {{ltf|c/string/byte/memset|memset_explicit}}
 * POSIX functions
 ** {{ltf|c/string/byte/memccpy}}
 ** {{ltf|c/string/byte/strdup}}
 ** {{ltf|c/string/byte/strndup}}
-** {{ltf|c/chrono/asctime|asctime_r}}
-** {{ltf|c/chrono/ctime|ctime_r}}
 ** {{ltf|c/chrono/gmtime|gmtime_r}}
 ** {{ltf|c/chrono/localtime|localtime_r}}
 ** Extensions for {{ltf|c/chrono/strftime}} and {{ltf|c/chrono/wcsftime}}
 * Extensions for {{ltf|c/io/fscanf}} and {{ltf|c/io/fprintf}} function families
 ** {{tt|w''N''}} and {{tt|wf''N''}} length modifiers for {{ltt|c/types/integer|[u]int''N''_t}} and {{ltt|c/types/integer|[u]int_fast''N''_t}} respectively
 ** {{tt|H}}, {{tt|D}}, and {{tt|DD}} length modifiers for {{c|_Decimal32}}, {{c|_Decimal64}}, and {{c|_Decimal128}} respectively
 ** {{tt|b}} conversion specifier for unsigned integer types
@@ Line 107: / Line 129: @@
 ** {{ltt|c/numeric/tgmath|__STDC_VERSION_TGMATH_H__}}
 ** {{ltt|c/chrono|__STDC_VERSION_TIME_H__}}
+** {{ltt|__STDC_VERSION_STDCKDINT_H__}}
+** {{ltt|__STDC_VERSION_STDBIT_H__}}
-== Defect reports ==
+==Defect reports==
 {{c/language/history/DR23}}
-== Compiler support ==
+==Compiler support==
 {{c/compiler support/23}}
 {{langlinks|ar|cs|de|es|fr|it|ja|ko|pl|pt|ru|tr|zh}}

Compiler support
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Program utilities
Variadic function support
Error handling
Dynamic memory management
Strings library
Algorithms
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Date and time utilities
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Difference between revisions of "c/23"

Latest revision as of 21:39, 9 February 2024

Contents

[edit] Obsolete

[edit] Removed

[edit] Deprecated

[edit] New language features

[edit] Feature test macros for optional features

[edit] New library features

[edit] New headers

[edit] Library features

[edit] Defect reports

[edit] Compiler support

[edit] C23 core language features

[edit] C23 library features

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