Member predicate NamedTypeReferent::getTypeDeclaration

Gets the source declaration of the type to which this tag refers, if any.

The source declaration of a constructor or interface type is the declaration of the type itself; the source declaration of an applied type is the source declaration of its head; the source declaration of a qualified type such as a nullable or non-nullable type is that of the underlying type.

For example, the source declaration of !Array<string> is (the declaration of) type Array, which is also the source declaration of !Array=. Primitive types, union types, and other complex kinds of types do not have a source declaration.