On 02/04/2017 15:31, Eduardo Habkost wrote: > When trying to change OBJECT and OBJECT_CHECK, I've found a > problem: gcc 6.2.1 can't evaluate typeof(*a) if *a has an > incomplete type, even inside the (const typeof(*(t)0) *) > expression used in QUALIFIED_CAST. It works on clang, though. > > I'm not sure we want to introduce something that would report > errors only on clang only[1]. Especially when the error messages > look like this: > hw/mem/pc-dimm.c:248:23: error: passing 'typeof (_Generic((const typeof > (*((typeof ((a)))0)) *)0, typeof ((a)): (const Object *)(0), default: (Object > *)(0)))' (aka 'const struct Object *') to parameter of type 'Object *' (aka > 'struct Object *') discards qualifiers > [-Werror,-Wincompatible-pointer-types-discards-qualifiers] > PCDIMMDevice *x = PC_DIMM(a); > > Lucikly all the OBJECT_CLASS usage I've found never involved > incomplete types, but they are more common when dealing with > object pointers. > > We could also require all users of OBJECT(x) to include the > header that defines the struct type of x. But I'm not sure it's > worth the effort.
Fair enough! Thanks for trying. Paolo
