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stddef.h: Add C2x unreachable macro

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C2x adds a macro unreachable to stddef.h, with the same semantics as
__builtin_unreachable.  Define this macro accordingly.

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

gcc/
	* ginclude/stddef.h [__STDC_VERSION__ > 201710L] (unreachable):
	New macro.

gcc/testsuite/
	* gcc.dg/c11-unreachable-1.c, gcc.dg/c2x-unreachable-1.c: New
	tests.
This commit is contained in:
Joseph Myers 2022-09-09 14:11:21 +00:00
parent e230f11e97
commit a1a53dc7d8
3 changed files with 42 additions and 0 deletions
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4
gcc/ginclude/stddef.h
View file

@ -451,6 +451,10 @@ typedef struct {
#endif
#endif /* C23. */
#if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710L
#define unreachable() (__builtin_unreachable ())
#endif
#endif /* _STDDEF_H was defined this time */
#endif /* !_STDDEF_H && !_STDDEF_H_ && !_ANSI_STDDEF_H && !__STDDEF_H__

9
gcc/testsuite/gcc.dg/c11-unreachable-1.c Normal file
View file

@ -0,0 +1,9 @@
/* Test unreachable not defined in <stddef.h> for C11. */
/* { dg-do preprocess } */
/* { dg-options "-std=c11 -pedantic-errors" } */
#include <stddef.h>
#ifdef unreachable
#error "unreachable defined"
#endif

29
gcc/testsuite/gcc.dg/c2x-unreachable-1.c Normal file
View file

@ -0,0 +1,29 @@
/* Test unreachable in <stddef.h> for C2x. */
/* { dg-do run } */
/* { dg-options "-std=c2x -pedantic-errors -O2" } */
#include <stddef.h>
#ifndef unreachable
#error "unreachable not defined"
#endif
extern void *p;
extern __typeof__ (unreachable ()) *p;
volatile int x = 1;
extern void not_defined (void);
extern void exit (int);
int
main ()
{
if (x == 2)
{
unreachable ();
not_defined ();
}
exit (0);
}