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https://issues.apache.org/jira/browse/GROOVY-9956?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Eric Milles resolved GROOVY-9956.
---------------------------------
Fix Version/s: 4.0.0-alpha-3
Resolution: Fixed
> Cannot infer correct type argument when passing a subtype of the declared
> type argument
> ---------------------------------------------------------------------------------------
>
> Key: GROOVY-9956
> URL: https://issues.apache.org/jira/browse/GROOVY-9956
> Project: Groovy
> Issue Type: Bug
> Components: Static compilation, Static Type Checker
> Affects Versions: 3.0.7, 4.0.0-alpha-2
> Reporter: Stefanos Chaliasos
> Assignee: Eric Milles
> Priority: Major
> Fix For: 4.0.0-alpha-3
>
>
> I have the following Groovy program.
> {code:groovy}
> class Foo<T> {
> T f;
> Foo (T f) {
> this.f = f;
> }
> }
> interface Bar{}
> class Baz<T> implements Bar {}
> @groovy.transform.TypeChecked
> class Main {
> public static void main(String[] args) {
> Foo<Bar> x1 = new Foo<Bar>(new Baz<Integer>()) // Compiles
> Foo<Bar> x2 = new Foo<>(new Baz<Integer>()) // Does not compile
> }
> }
> {code}
> h2. Actual Behavior
> The program does not compile, and I get the following error.
> {code:java}
> org.codehaus.groovy.control.MultipleCompilationErrorsException: startup
> failed:
> Main.groovy: 16: [Static type checking] - Incompatible generic argument
> types. Cannot assign Foo <Baz> to: Foo <Bar>
> @ line 16, column 19.
> Foo<Bar> x2 = new Foo<>(new Baz<Integer>())
> ^
> 1 error
> {code}
> h2. Expected Behavior
> Compile successfully.
> h2. Affected Version
> I have also tested it with the compiler from Master (commit:
> 666627b3be7718e3265fc42b473060bc73f42e2f).
> h2. Comment
> If I remove the type parameter from Baz, then it only fails when compiled
> with the compiler from the Master.
> Specifically, the following test case compiles with 3.0.7 and 4.0.0-alpha-2
> compilers but fails with the same message as the previous test case when
> using the compiler from the Master.
> {code:groovy}
> class Foo<T> {
> T f;
> Foo (T f) {
> this.f = f;
> }
> }
> interface Bar{}
> class Baz implements Bar {}
> @groovy.transform.TypeChecked
> class Main {
> public static void main(String[] args) {
> Foo<Bar> x1 = new Foo<Bar>(new Baz()) // Compiles
> Foo<Bar> x2 = new Foo<>(new Baz()) // Does not compile
> }
> }
> {code}
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