case *ast.StarExpr: // possibly an embedded type literal
		r.filterType(nil, t.X)
	case *ast.UnaryExpr:
		if t.Op == token.TILDE { // approximation element
			r.filterType(nil, t.X)
		}
	case *ast.BinaryExpr:
		if t.Op == token.OR { // union
			r.filterType(nil, t.X)
			r.filterType(nil, t.Y)
		}
	case *ast.ArrayType:
		r.filterType(nil, t.Elt)
	case *ast.StructType: