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[C99] Fix definitions of INTn_C macros (#133916)
C99 introduced macros of the form `INTn_C(v)` which expand to a signed or unsigned integer constant with the specified value `v` and the type `int_leastN_t`. Clang's initial implementation of these macros used token pasting to form the integer constants, but this means that users cannot define a macro named `L`, `U`, `UL`, etc before including `<stdint.h>` (in freestanding mode, where Clang's header is being used) because that could form invalid token pasting results. The new definitions now use the predefined `__INTn_C` macros instead of using token pasting. This matches the behavior of GCC. Fixes #85995
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‎clang/docs/ReleaseNotes.rst‎

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@@ -337,6 +337,9 @@ Bug Fixes in This Version
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- Fixed a problematic case with recursive deserialization within ``FinishedDeserializing()`` where
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``PassInterestingDeclsToConsumer()`` was called before the declarations were safe to be passed. (#GH129982)
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- Fixed a modules crash where an explicit Constructor was deserialized. (#GH132794)
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- Defining an integer literal suffix (e.g., ``LL``) before including
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``<stdint.h>`` in a freestanding build no longer causes invalid token pasting
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when using the ``INTn_C`` macros. (#GH85995)
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Bug Fixes to Compiler Builtins
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

‎clang/lib/Headers/stdint.h‎

Lines changed: 18 additions & 129 deletions
Original file line numberDiff line numberDiff line change
@@ -317,166 +317,55 @@ typedef __UINTMAX_TYPE__ uintmax_t;
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* integer width that the target implements, so corresponding macros are
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* defined below, too.
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*
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* These macros are defined using the same successive-shrinking approach as
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* the type definitions above. It is likewise important that macros are defined
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* in order of decending width.
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*
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* Note that C++ should not check __STDC_CONSTANT_MACROS here, contrary to the
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* claims of the C standard (see C++ 18.3.1p2, [cstdint.syn]).
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*/
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328-
#define __int_c_join(a, b) a ## b
329-
#define __int_c(v, suffix) __int_c_join(v, suffix)
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#define __uint_c(v, suffix) __int_c_join(v##U, suffix)
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332-
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#ifdef __INT64_TYPE__
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# undef __int64_c_suffix
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# undef __int32_c_suffix
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# undef __int16_c_suffix
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# undef __int8_c_suffix
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# ifdef __INT64_C_SUFFIX__
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# define __int64_c_suffix __INT64_C_SUFFIX__
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# define __int32_c_suffix __INT64_C_SUFFIX__
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# define __int16_c_suffix __INT64_C_SUFFIX__
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# define __int8_c_suffix __INT64_C_SUFFIX__
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# endif /* __INT64_C_SUFFIX__ */
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#endif /* __INT64_TYPE__ */
345-
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#ifdef __int_least64_t
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# ifdef __int64_c_suffix
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# define INT64_C(v) __int_c(v, __int64_c_suffix)
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# define UINT64_C(v) __uint_c(v, __int64_c_suffix)
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# else
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# define INT64_C(v) v
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# define UINT64_C(v) v ## U
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# endif /* __int64_c_suffix */
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#define INT64_C(v) __INT64_C(v)
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#define UINT64_C(v) __UINT64_C(v)
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#endif /* __int_least64_t */
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#ifdef __INT56_TYPE__
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# undef __int32_c_suffix
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# undef __int16_c_suffix
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# undef __int8_c_suffix
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# ifdef __INT56_C_SUFFIX__
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# define INT56_C(v) __int_c(v, __INT56_C_SUFFIX__)
363-
# define UINT56_C(v) __uint_c(v, __INT56_C_SUFFIX__)
364-
# define __int32_c_suffix __INT56_C_SUFFIX__
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# define __int16_c_suffix __INT56_C_SUFFIX__
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# define __int8_c_suffix __INT56_C_SUFFIX__
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# else
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# define INT56_C(v) v
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# define UINT56_C(v) v ## U
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# endif /* __INT56_C_SUFFIX__ */
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#define INT56_C(v) __INT56_C(v)
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#define UINT56_C(v) __UINT56_C(v)
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#endif /* __INT56_TYPE__ */
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#ifdef __INT48_TYPE__
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# undef __int32_c_suffix
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# undef __int16_c_suffix
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# undef __int8_c_suffix
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# ifdef __INT48_C_SUFFIX__
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# define INT48_C(v) __int_c(v, __INT48_C_SUFFIX__)
380-
# define UINT48_C(v) __uint_c(v, __INT48_C_SUFFIX__)
381-
# define __int32_c_suffix __INT48_C_SUFFIX__
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# define __int16_c_suffix __INT48_C_SUFFIX__
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# define __int8_c_suffix __INT48_C_SUFFIX__
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# else
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# define INT48_C(v) v
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# define UINT48_C(v) v ## U
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# endif /* __INT48_C_SUFFIX__ */
337+
#define INT48_C(v) __INT48_C(v)
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#define UINT48_C(v) __UINT48_C(v)
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#endif /* __INT48_TYPE__ */
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#ifdef __INT40_TYPE__
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# undef __int32_c_suffix
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# undef __int16_c_suffix
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# undef __int8_c_suffix
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# ifdef __INT40_C_SUFFIX__
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# define INT40_C(v) __int_c(v, __INT40_C_SUFFIX__)
397-
# define UINT40_C(v) __uint_c(v, __INT40_C_SUFFIX__)
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# define __int32_c_suffix __INT40_C_SUFFIX__
399-
# define __int16_c_suffix __INT40_C_SUFFIX__
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# define __int8_c_suffix __INT40_C_SUFFIX__
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# else
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# define INT40_C(v) v
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# define UINT40_C(v) v ## U
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# endif /* __INT40_C_SUFFIX__ */
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#define INT40_C(v) __INT40_C(v)
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#define UINT40_C(v) __UINT40_C(v)
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#endif /* __INT40_TYPE__ */
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408-
#ifdef __INT32_TYPE__
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# undef __int32_c_suffix
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# undef __int16_c_suffix
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# undef __int8_c_suffix
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# ifdef __INT32_C_SUFFIX__
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# define __int32_c_suffix __INT32_C_SUFFIX__
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# define __int16_c_suffix __INT32_C_SUFFIX__
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# define __int8_c_suffix __INT32_C_SUFFIX__
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# endif /* __INT32_C_SUFFIX__ */
417-
#endif /* __INT32_TYPE__ */
418-
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#ifdef __int_least32_t
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# ifdef __int32_c_suffix
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# define INT32_C(v) __int_c(v, __int32_c_suffix)
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# define UINT32_C(v) __uint_c(v, __int32_c_suffix)
423-
# else
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# define INT32_C(v) v
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# define UINT32_C(v) v ## U
426-
# endif /* __int32_c_suffix */
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#define INT32_C(v) __INT32_C(v)
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#define UINT32_C(v) __UINT32_C(v)
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#endif /* __int_least32_t */
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#ifdef __INT24_TYPE__
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# undef __int16_c_suffix
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# undef __int8_c_suffix
433-
# ifdef __INT24_C_SUFFIX__
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# define INT24_C(v) __int_c(v, __INT24_C_SUFFIX__)
435-
# define UINT24_C(v) __uint_c(v, __INT24_C_SUFFIX__)
436-
# define __int16_c_suffix __INT24_C_SUFFIX__
437-
# define __int8_c_suffix __INT24_C_SUFFIX__
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# else
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# define INT24_C(v) v
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# define UINT24_C(v) v ## U
441-
# endif /* __INT24_C_SUFFIX__ */
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#define INT24_C(v) __INT24_C(v)
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#define UINT24_C(v) __UINT24_C(v)
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#endif /* __INT24_TYPE__ */
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445-
#ifdef __INT16_TYPE__
446-
# undef __int16_c_suffix
447-
# undef __int8_c_suffix
448-
# ifdef __INT16_C_SUFFIX__
449-
# define __int16_c_suffix __INT16_C_SUFFIX__
450-
# define __int8_c_suffix __INT16_C_SUFFIX__
451-
# endif /* __INT16_C_SUFFIX__ */
452-
#endif /* __INT16_TYPE__ */
453-
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#ifdef __int_least16_t
455-
# ifdef __int16_c_suffix
456-
# define INT16_C(v) __int_c(v, __int16_c_suffix)
457-
# define UINT16_C(v) __uint_c(v, __int16_c_suffix)
458-
# else
459-
# define INT16_C(v) v
460-
# define UINT16_C(v) v ## U
461-
# endif /* __int16_c_suffix */
361+
#define INT16_C(v) __INT16_C(v)
362+
#define UINT16_C(v) __UINT16_C(v)
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#endif /* __int_least16_t */
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464365

465-
#ifdef __INT8_TYPE__
466-
# undef __int8_c_suffix
467-
# ifdef __INT8_C_SUFFIX__
468-
# define __int8_c_suffix __INT8_C_SUFFIX__
469-
# endif /* __INT8_C_SUFFIX__ */
470-
#endif /* __INT8_TYPE__ */
471-
472366
#ifdef __int_least8_t
473-
# ifdef __int8_c_suffix
474-
# define INT8_C(v) __int_c(v, __int8_c_suffix)
475-
# define UINT8_C(v) __uint_c(v, __int8_c_suffix)
476-
# else
477-
# define INT8_C(v) v
478-
# define UINT8_C(v) v ## U
479-
# endif /* __int8_c_suffix */
367+
#define INT8_C(v) __INT8_C(v)
368+
#define UINT8_C(v) __UINT8_C(v)
480369
#endif /* __int_least8_t */
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482371

@@ -938,8 +827,8 @@ typedef __UINTMAX_TYPE__ uintmax_t;
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#endif
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940829
/* 7.18.4.2 Macros for greatest-width integer constants. */
941-
#define INTMAX_C(v) __int_c(v, __INTMAX_C_SUFFIX__)
942-
#define UINTMAX_C(v) __int_c(v, __UINTMAX_C_SUFFIX__)
830+
#define INTMAX_C(v) __INTMAX_C(v)
831+
#define UINTMAX_C(v) __UINTMAX_C(v)
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944833
/* C23 7.22.3.x Width of other integer types. */
945834
#if defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L

‎clang/test/C/drs/dr209.c‎

Lines changed: 2 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -4,6 +4,7 @@
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RUN: %clang_cc1 -std=c17 -ffreestanding -fsyntax-only -verify -pedantic %s
55
RUN: %clang_cc1 -std=c2x -ffreestanding -fsyntax-only -verify -pedantic %s
66
*/
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// expected-no-diagnostics
78

89
/* WG14 DR209: partial
910
* Problem implementing INTN_C macros
@@ -33,8 +34,7 @@ void dr209(void) {
3334
(void)_Generic(INT16_C(0), __typeof__(+(int_least16_t){0}) : 1);
3435
(void)_Generic(INT32_C(0), __typeof__(+(int_least32_t){0}) : 1);
3536
(void)_Generic(INT64_C(0), __typeof__(+(int_least64_t){0}) : 1);
36-
// FIXME: This is not the expected behavior; the type of the expanded value
37-
// in both of these cases should be 'int',
37+
// The type of the expanded value in both of these cases should be 'int',
3838
//
3939
// C99 7.18.4p3: The type of the expression shall have the same type as would
4040
// an expression of the corresponding type converted according to the integer
@@ -53,8 +53,6 @@ void dr209(void) {
5353
//
5454
(void)_Generic(UINT8_C(0), __typeof__(+(uint_least8_t){0}) : 1);
5555
(void)_Generic(UINT16_C(0), __typeof__(+(uint_least16_t){0}) : 1);
56-
// expected-error@-2 {{controlling expression type 'unsigned int' not compatible with any generic association type}}
57-
// expected-error@-2 {{controlling expression type 'unsigned int' not compatible with any generic association type}}
5856
(void)_Generic(UINT32_C(0), __typeof__(+(uint_least32_t){0}) : 1);
5957
(void)_Generic(UINT64_C(0), __typeof__(+(uint_least64_t){0}) : 1);
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}

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