On Tue, Sep 10, 2024 at 06:02:45PM +0000, Qing Zhao wrote:
> > #define alloc(P, FAM, COUNT) ({ \
> > __auto_type __p = &(P); \
> > __auto_type __c = (COUNT); \
> > size_t __size = sizeof(*(*__p)) + sizeof(*(*__p)->FAM) * __c; \
Shouldn't that be
size_t __size = offsetof(__typeof(*__p), FAM) + sizeof(*(*__p)->FAM) * __c; \
?
> > if ((*__p = malloc(__size))) { \
> > __auto_type ret = __builtin_counted_by_ref((*__p)->FAM); \
> > *_Generic(ret, void *: &(size_t){0}, default: ret) = __c; \
> > } \
> > })
> >
> > to have brackets around the macro arguments to avoid accidents,
> > to reduce compile time due to multiple evaluation of the macro
> > arguments, and to avoid warnings for the null pointer dereference
> > on clang.
Jakub
