From: David Laight > Sent: 28 July 2024 19:15 > > From: Linus Torvalds > > Sent: 28 July 2024 17:57 > > > > On Sun, 28 Jul 2024 at 07:21, David Laight <David.Laight@xxxxxxxxxx> wrote: > > > > > > +/* Allow if both x and y are valid for either signed or unsigned compares. */ > > > +#define __types_ok(x, y) \ > > > + ((__is_ok_signed(x) && __is_ok_signed(y)) || \ > > > + (__is_ok_unsigned(x) && __is_ok_unsigned(y))) > > > > This seems horrendous, exactly because it expands both x and y twice. > > And the "expand multiple times" was really the fundamental problem. > > This version is better than the previous one ;-) > > > Why not just change the model to say it's a bitmask of "signedness > > bits", the bits are "signed ok" and "unsigned ok", and turn it into > > > > /* Signedness matches? */ > > #define __types_ok(x, y) \ > > (__signedness_bits(x) & __signedness_bits(y)) > > Something like that might work, but it would take some effort to get right. Actually it doesn't work. The checks are is_signed((x) + 0) and is_unsigned((x)) so that 'unsigned char' can be compared against both 'int' and 'unsigned int'. But the signedness tests can use _unique_x which is trivially short. That needs a pre-change to pass __COUNTER__ through (as in min3()). David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
