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https://issues.apache.org/jira/browse/GROOVY-9998?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Eric Milles updated GROOVY-9998:
--------------------------------
Fix Version/s: 3.0.20
> Wildcards with a lower bound fail static type checking
> ------------------------------------------------------
>
> Key: GROOVY-9998
> URL: https://issues.apache.org/jira/browse/GROOVY-9998
> Project: Groovy
> Issue Type: Bug
> Components: Static compilation, Static Type Checker
> Affects Versions: 3.0.7
> Reporter: Lyuben Atanasov
> Assignee: Eric Milles
> Priority: Major
> Fix For: 4.0.0-alpha-3, 3.0.20
>
>
> The following code fails to compile when using {{@CompileStatic}}:
> {code}
> class A {
> public final int order;
>
> public A(int order) {
> this.order = order;
> }
> }
> class B extends A {
> public B(int order) {
> super(order);
> }
> }
> class Test {
> public void test() {
> Comparator<? super A> comparator = (a1, a2) ->
> Integer.compare(a1.order, a2.order);
> List<B> list = [new B(2), new B(3), new B(1), new B(0)];
> list.stream().sorted(comparator);
> }
> }
> {code}
> The error is:
> {noformat}
> Exception in thread "main"
> org.codehaus.groovy.control.MultipleCompilationErrorsException: startup
> failed:
> Script_49a5c0348548765c6a0257437aa3b031.groovy: 19: [Static type checking] -
> Cannot call java.util.stream.Stream <B>#sorted(java.util.Comparator <? super
> B>) with arguments [java.util.Comparator <A>]
> @ line 19, column 3.
> list.stream().sorted(comparator);
> ^
> {noformat}
> For some reason the type checker is confused when we have a method with a
> generic parameter that has a wildcard with a lower bound. The same code
> compiles with javac if I move the A and B classes to separate files and
> create the list java-style.
> Curiously, if I change the comparator's type from {{Comparator<? super A>}}
> to {{Comparator<? extends A>}}, the code compiles successfully in Groovy (and
> it shouldn't!), but causes compilation failure in Java.
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