Attr.checkId()方法

1、符号sym是TYP02

举个例子，如下：

package bazola;
class Point {
	// ...
}
class Tree<A> {
	class AttrVisitor {
		// ...
	}
}
class PointTree extends Tree<Point> {
	public void test(){
		// 会将PointTree.AttrVisitor更改为Tree<Point>.AttrVisitor
		PointTree.AttrVisitor x = null;
	}
}

方法各个参数值如下：

JCTree tree = PointTree.AttrVisitor
Type site = bazola.PointTree
Symbol sym = bazola.Tree.AttrVisitor
Env<AttrContext> env = Env[AttrContext[Scope[ | | super, this]],outer=Env[AttrContext[Scope[bazola.PointTree, bazola.Tree, bazola.Point, bazola.Gabriel]]]]　　

int protoKindsSymbol = 2
Type protoTypesTagType = <none>
boolean useVarargs = false

normOuter = bazola.Tree<bazola.Point>

2、符号sym是VAR04

3、符号sym是MTH16

4、符号sym是PCK01或者ERR31