The composite type of two compatible array types is an array with
the composite element type. The sizes of both original types must be equivalent
if they are known.
If the size of only one of the original array types
is known, then the composite type has that size. For example: char ex3[];
char ex4[42];
The composite type of
ex3 and
ex4 is
char[42].
If one of the original types is a variable length array, the composite type
is that type.