Abstract classes not used as children treated as roots

[Jesper Mattsson]

Abstract node types that are not directly used as children of any node are treated as root types when giving warnings about missing equations for inherited attributes.

Example:

abstract A ::= C*;
B : A;
C : A;

aspect Test {

inh boolean C.inhTest();
eq B.getChild().inhTest() = true;

}

This gives the warning:

Warning at Test.jrag:3: missing inherited equation for attribute inhTest in class C when being child of A (path: A->C), C (path: A->C->C)