You are viewing a plain text version of this content. The canonical link for it is here.
Posted to notifications@groovy.apache.org by "Yuriy Kiselev (JIRA)" <ji...@apache.org> on 2017/01/04 23:35:58 UTC
[jira] [Updated] (GROOVY-8034) Compile error when using generic
type with lower bound
[ https://issues.apache.org/jira/browse/GROOVY-8034?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Yuriy Kiselev updated GROOVY-8034:
----------------------------------
Description:
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
"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.
was:
I'm trying to implement chained generics. It works as Java code but failed 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
"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.
> 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
> Affects Versions: 2.4.6
> Environment: org.codehaus.groovy:groovy-all:2.4.6 in maven project
> Reporter: Yuriy Kiselev
>
> 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
> "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
(v6.3.4#6332)