In PL/I you can declare arrays with a length descriptor, thus allocating storage for the length, like in mostly safe systems languages.

Alternatively when allocating the array storage define its access to be pointer based.

This means no length descriptor will be stored alongside the array, and the access to array elements will be done via the given pointer.

It is up to the programmer not to mess up then.

Unfortunately C authors never added a way to do the former, given their experience with PL/I and Multics.

I am aware we are finally going into that direction.