generics - GroovyAST 在编译时添加通用字段

Question

我想在编译时向某些类添加通用字段。为了这个目标，我按照官方 documentation 实现了自己的 AST 注释和转换类。并使用 AST 注释来注释所需的类。

但是我在编译时收到此错误:

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed: /home/.../groovy/Sample.groovy: -1: A transform used a generics containing ClassNode java.util.HashSet for the field x directly. You are not supposed to do this. Please create a new ClassNode referring to the old ClassNode and use the new ClassNode instead of the old one. Otherwise the compiler will create wrong descriptors and a potential NullPointerException in TypeResolver in the OpenJDK. If this is not your own doing, please report this bug to the writer of the transform. @ line -1, column -1.

我是不是搞错了？

示例代码

例如，假设我想添加 HashSet<Long>字段，名为 x ，对于每个由 MyAST 注释的类注释。

我的 AST 注释类:

@Retention(RetentionPolicy.SOURCE)
@Target(ElementType.TYPE)
@GroovyASTTransformationClass(classes = [MyASTTransformation.class])
public @interface MyAST {
}

我的 AST 转换类:

@CompileStatic
@GroovyASTTransformation(phase = CompilePhase.SEMANTIC_ANALYSIS)
public class MyASTTransformation implements ASTTransformation {

@Override
public void visit(ASTNode[] nodes, SourceUnit sourceUnit) {
     ClassNode clazz = (ClassNode) nodes[1];
     ClassNode longHashSetClass = new ClassNode(HashSet.class);
     longHashSetClass.setGenericsTypes([new GenericsType(new ClassNode(Long.class))] as GenericsType[]);
     FieldNode field = new FieldNode("x", FieldNode.ACC_PRIVATE, longHashSetClass, clazz, new ConstantExpression(null));
     clazz.addField(field);
 }
}

带注释的类示例:

@MyAST
public class Sample {
}

注意

当我删除行 longHashSetClass.setGenericsTypes([new GenericsType(new ClassNode(Long.class))] as GenericsType[]); 时，一切正常，但类型为 x是 HashSet而不是HashSet<Long>在运行时。

Answer 1

您应该使用ClassHelper或GenericUtils来创建ClassNode:

import static org.codehaus.groovy.ast.ClassHelper.make
import static org.codehaus.groovy.ast.tools.GenericsUtils.makeClassSafeWithGenerics

...

ClassNode hashSet = makeClassSafeWithGenerics(HashSet, make(Long))