[jira] [Comment Edited] (GROOVY-10631) Unable to instantiate type parameter of method with a valid type

["Thodoris Sotiropoulos (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/GROOVY-10631?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17540360#comment-17540360 ] 

Thodoris Sotiropoulos edited comment on GROOVY-10631 at 5/21/22 6:45 AM:
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It doesn't matter. The compiler infers the type of type variable T by considering *both* argument and return type. Based on these constraints, the only assignment of T that is valid is type A<? extends Object>.


was (Author: theosot):
It doesn't matter. The compiler infers the type of type variable T by considering *both* argument and return type. Based on this constraints, the only assignment of T that is valid is type A<? extends Object>.

> Unable to instantiate type parameter of method with a valid type
> ----------------------------------------------------------------
>
>                 Key: GROOVY-10631
>                 URL: https://issues.apache.org/jira/browse/GROOVY-10631
>             Project: Groovy
>          Issue Type: Bug
>          Components: Static Type Checker
>            Reporter: Thodoris Sotiropoulos
>            Assignee: Eric Milles
>            Priority: Major
>
> I have the following program
> {code}
> class A<T> {}
> class Test {
>     static <T> T m(T x, T y) { return null; }
>     static void test() {
>         A<? extends Object> x = m(new A<Boolean>(), new A<String>());
>     }
> }
> {code}
> h3. Actual behaviour
> {code}
> org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
> test.groovy: 8: [Static type checking] - Cannot call <T> Test#m(T, T) with arguments [A<java.lang.Boolean>, A<java.lang.String>]
>  @ line 8, column 33.
>            A<? extends Object> x = m(new A<Boolean>(), new A<String>());
>                                    ^
> 1 error
> {code}
> h3. Expected behavior
> Compile successfully
> Tested against master (commit: a976ecdee1f17f7fafc55767de2d857c44d44697)



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