[
https://issues.apache.org/jira/browse/GROOVY-8034?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Paul King closed GROOVY-8034.
-----------------------------
> Compile error when using generic type with lower bound
> ------------------------------------------------------
>
> Key: GROOVY-8034
> URL: https://issues.apache.org/jira/browse/GROOVY-8034
> Project: Groovy
> Issue Type: Bug
> Components: Static Type Checker
> Affects Versions: 2.4.6, 2.4.7
> Environment: groovy JDK 2.4.7, 2.4.6,
> Java used: jdk1.7.0_51, jdk1.8.0_40, 9-ea+114,
> RedHat\java-1.8.0-openjdk-1.8.0.111-3
> Reporter: Yuriy Kiselev
> Assignee: Eric Milles
> Priority: Major
> Fix For: 4.0.0-alpha-3
>
>
> I'm trying to implement chained generics. It works as Java code but fails to
> compile by groovyc:
> {code}
> Error:(38, 9) Groovyc: [Static type checking] - Cannot call <C extends
> com.github.ykiselev.ChainTest.A<? super O, ?>>
> com.github.ykiselev.ChainTest$A <? super O -> java.lang.Object, ?>#andThen(C)
> with arguments [com.github.ykiselev.ChainTest$A <Double, String>]
> {code}
> Code (JUnit4 unit test)
> {code}
> package com.github.ykiselev
> import groovy.transform.TypeChecked
> import org.junit.Test
> @TypeChecked
> class ChainTest {
> static class A<I, O> {
> def <C extends A<? super O, ?>> C andThen(C next) {
> return next
> }
> }
> static <I, O, C extends A<? super O, ?>> C chain(A<I, O> self, C next) {
> self.andThen(next)
> return next
> }
> @Test
> void "should chain"() {
> def a1 = new A<String, Integer>()
> def a2 = new A<Integer, Double>()
> def a3 = new A<Double, String>()
> def a4 = new A<String, Double>()
> def a5 = new A<Number, Object>()
> a1.andThen(a2) // ok
> a2.andThen(a3) // ok
> a3.andThen(a4) // ok
> a4.andThen(a5) // ok (even without "? super O")
> chain(a1, a2).andThen(a3) // ok
> chain(chain(chain(chain(a1, a2), a3), a4), a5) // ok
> a1.andThen(a2)
> .andThen(a3) // static type checker error
> .andThen(a4)
> .andThen(a5)
> }
> }
> {code}
> This would compile if I change bounded type parameter like this:
> {code}
> def <C extends A<O, ?>> C andThen(C next) {
> return next
> }
> {code}
> but I need it bounded.
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
