Is there a non-array incomplete type?

Question

All I have found in C11 Standard for incomplete types are incomplete array types.

I was wondering if there is a non-array incomplete type.

Answer 1

An incomplete type is a type that describes an identifier but lacks information needed to determine the size of the identifier. An "incomplete type" can be

• A structure type whose members you have not yet specified.

• A union type whose members you have not yet specified.

• An array type whose dimension you have not yet specified.

The void type is an incomplete type that cannot be completed