From: Arnd Bergmann > Sent: 24 July 2024 18:32 > > On Wed, Jul 24, 2024, at 16:29, David Laight wrote: > > > +#define __if_constexpr(expr, if_const, if_not_const) \ > > + _Generic(0 ? ((void *)((long)(expr) * 0l)) : (char *)0, \ > > + char *: (if_const), \ > > + void *: (if_not_const)) > > + > > -#define __is_constexpr(x) \ > > - (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8))) > > +#define __is_constexpr(expr) __if_constexpr((expr), 1, 0) > > I don't immediately see anything wrong with this, but I'm > still scared of any change to it, especially if this is > meant to go straight into mainline. Well it would be -rc1 (or maybe -rc2). > Would it be possible to do patch 4/7 without the new > __if_constexpr() and instead still using __builtin_choose_expr()? The safer option would be to add __if_constexpr() but leave the change to __is_constexpr() for 'next'. David > > Arnd - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
