Thodoris Sotiropoulos created GROOVY-11446:
----------------------------------------------
Summary: Missing type mismatch when dealing with a polymorphic
function expecting a wildcard
Key: GROOVY-11446
URL: https://issues.apache.org/jira/browse/GROOVY-11446
Project: Groovy
Issue Type: Bug
Components: Static Type Checker
Reporter: Thodoris Sotiropoulos
I have the following program
{code:java}
class Test {
public static void main(String[] args) {
List<?> d = ["fda"];
List<Number> x = m(d);
x[0].intValue();
}
public static <T> List<T> m(List<? extends T> x) { return x }
} {code}
h3. Actual behavior
The code compiles, but when running the program I receive the following
exception
{code:java}
Exception in thread "main" java.lang.ClassCastException: class java.lang.String
cannot be cast to class java.lang.Number (java.lang.String and java.lang.Number
are in module java.base of loader 'bootstrap')
at Test.main(test.groovy:5) {code}
h3. Expected behavior
The code should have been rejected, as the return type of method `m()` is
List<?>, which is incompatible with the expected type List<Number>
h3. Notes
Notably, when changing the signature of method m as
{code:java}
public static <T> List<T> m(List<T> x) { return null; } {code}
the code is rejected as expected.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
