From: Zhangjin Wu > Sent: 07 August 2023 06:58 ... > +/* __auto_type is used instead of __typeof__ to workaround the build error > + * 'error: assignment of read-only variable' when the argument has 'const' in > + * the type, but __auto_type is a new feature from newer gcc version and it > + * only works with 'const' from gcc 11.0 (__GXX_ABI_VERSION = 1016) > + * https://gcc.gnu.org/legacy-ml/gcc-patches/2013-11/msg01378.html > + */ You can use typeof((x) + 0) to lose the 'const' flag. The only downside is that char/short become int. > + > +#if __GXX_ABI_VERSION >= 1016 > +#define __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT > +#endif > + > +#ifdef __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT > +#define __sysret(arg) \ > +({ \ > + __auto_type __ret = (arg); \ > + if (__is_signed_type(__typeof__(arg))) { \ > + if (__ret < 0) { \ > + SET_ERRNO(-(long)__ret); \ > + __ret = (__typeof__(arg))(-1L); \ > + } \ > + } else { \ > + if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \ > + SET_ERRNO(-(long)__ret); \ > + __ret = (__typeof__(arg))(-1L); \ > + } \ > + } \ > + __ret; \ > +}) > + > +#else /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */ > +#define __sysret(arg) \ > +({ \ > + long __ret = (long)(arg); \ > + if (__is_signed_type(__typeof__(arg))) { \ > + if (__ret < 0) { \ > + SET_ERRNO(-__ret); \ > + __ret = -1L; \ > + } \ > + } else { \ > + if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \ > + SET_ERRNO(-__ret); \ > + __ret = -1L; \ > + } \ > + } \ > + (__typeof__(arg))__ret; \ > +}) > +#endif /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */ with (retyped so it may be wrong): #define is_constexpr(x) sizeof(*(0 ? (void *)((long)(x) * 0) : (int *)0)) == 1) and (because even (void *)0 isn't completely constant): #define is_pointer(x) (!is_constexpr((typeof(x))0)) You can probably do: #define __sysret(arg) \ ({ \ typeof((arg) + 0) __ret = arg; \ if (__built_choose_expr(is_pointer(arg), (unsigned long)-(MAX_ERRNO+1), __ret) \ < (__built_choose_expr(is_pointer(arg), (unsigned long)__ret, 0)) { \ SET_ERRNO(-__ret); \ __reg = typeof(ret)-1L; \ } \ __ret; \ }) Apart from the annoyance of having to reverse the conditional that only has one copy of the check. Using two __builtin_choose_expr() saves you having to write two comparisons that are valid for both pointer and integer. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
