1#ifndef __wint_t_defined
2#define __wint_t_defined 1
3
4/* Some versions of stddef.h provide wint_t, even though neither the
5 C nor C++ standards, nor POSIX, specifies this. We assume that
6 stddef.h will define the macro _WINT_T if and only if it provides
7 wint_t, and conversely, that it will avoid providing wint_t if
8 _WINT_T is already defined. */
9#ifndef _WINT_T
10#define _WINT_T 1
11
12/* Integral type unchanged by default argument promotions that can
13 hold any value corresponding to members of the extended character
14 set, as well as at least one value that does not correspond to any
15 member of the extended character set. */
16#ifndef __WINT_TYPE__
17# define __WINT_TYPE__ unsigned int
18#endif
19
20typedef __WINT_TYPE__ wint_t;
21
22#endif /* _WINT_T */
23#endif /* bits/types/wint_t.h */
24

source code of glibc/wcsmbs/bits/types/wint_t.h