diff options
Diffstat (limited to 'bits')
| -rw-r--r-- | bits/wchar.h | 28 |
1 files changed, 26 insertions, 2 deletions
diff --git a/bits/wchar.h b/bits/wchar.h index eb07151152..ef93d0e784 100644 --- a/bits/wchar.h +++ b/bits/wchar.h @@ -19,7 +19,31 @@ #ifndef _BITS_WCHAR_H #define _BITS_WCHAR_H 1 -#define __WCHAR_MIN (-2147483647 - 1) -#define __WCHAR_MAX (2147483647) +/* The fallback definitions, for when __WCHAR_MAX__ or __WCHAR_MIN__ + are not defined, give the right value and type as long as both int + and wchar_t are 32-bit types. Adding L'\0' to a constant value + ensures that the type is correct; it is necessary to use (L'\0' + + 0) rather than just L'\0' so that the type in C++ is the promoted + version of wchar_t rather than the distinct wchar_t type itself. + Because wchar_t in preprocessor #if expressions is treated as + intmax_t or uintmax_t, the expression (L'\0' - 1) would have the + wrong value for WCHAR_MAX in such expressions and so cannot be used + to define __WCHAR_MAX in the unsigned case. */ + +#ifdef __WCHAR_MAX__ +# define __WCHAR_MAX __WCHAR_MAX__ +#elif L'\0' - 1 > 0 +# define __WCHAR_MAX (0xffffffffu + L'\0') +#else +# define __WCHAR_MAX (0x7fffffff + L'\0') +#endif + +#ifdef __WCHAR_MIN__ +# define __WCHAR_MIN __WCHAR_MIN__ +#elif L'\0' - 1 > 0 +# define __WCHAR_MIN (L'\0' + 0) +#else +# define __WCHAR_MIN (-__WCHAR_MAX - 1) +#endif #endif /* bits/wchar.h */ |