I really want C to have a slice/fat-pointer-array type, because C is the least common denominator for ABIs and any kind of FFI, and since it doesn't have something like that, it complicates FFI from languages that have a more sane way of handling arrays.

I'd even be happy if the standard just included a macro like:

#define ARRAY(T) struct { T *ptr, size_t len }

Along with a few functions for working with such types.

Although that would be kind of unwieldy to use in C, since you would need a typedef to actually use any specific types.