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Posted to notifications@groovy.apache.org by "Eric Milles (Jira)" <ji...@apache.org> on 2020/10/06 14:18:00 UTC
[jira] [Commented] (GROOVY-9762) Wrong type resolved if method
reference used with typed method
[ https://issues.apache.org/jira/browse/GROOVY-9762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17208786#comment-17208786 ]
Eric Milles commented on GROOVY-9762:
-------------------------------------
Can you retest with Groovy 3.0.6? There was a change for method pointers/references to inference the closure return type.
> Wrong type resolved if method reference used with typed method
> --------------------------------------------------------------
>
> Key: GROOVY-9762
> URL: https://issues.apache.org/jira/browse/GROOVY-9762
> Project: Groovy
> Issue Type: Bug
> Components: Compiler
> Affects Versions: 3.0.5
> Reporter: Marcin Zajaczkowski
> Assignee: Eric Milles
> Priority: Minor
>
> I've encountered a problem with type checking if a method reference is used.
> In following (stripped down from the original production case) code in the line with the error variable the following error is reported:
> {code:java}
> > Task :compileTestGroovy
> startup failed:
> /home/foobar.../MethodReferenceProblemWithType.groovy: 15: [Static type checking] - Cannot assign value of type java.lang.Object to variable of type java.util.List <Integer>
> @ line 15, column 31.
> List<Integer> error = opt.map(this::just).get() {code}
> {code:java}
> @CompileStatic
> class MethodReferenceProblemWithType {
> static void reproduce() {
> Optional<Integer> opt = Optional.ofNullable(Integer.valueOf(1))
> List<Integer> ok = opt.map(o -> just(o)).get() //ok
> List<Integer> error = opt.map(this::just).get() //problem
> }
> private static <T> List<T> just(T data) {
> return new ArrayList<T>();
> }
> } {code}
> If `@CompileStatic` is removed, I still see a type incompatibility warning in Idea. Switching to lambda is a workaround, therefore it's just a minor glitch. Tested with Groovy 3.0.5.
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