[GROOVY-10222] Unable to infer the type parameter of a parameterized function

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-beta-2
• Component/s: Static Type Checker
• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 10/Sep/21 12:53
• Updated: 18/May/22 19:54
• Resolved: 12/Oct/21 15:31

Description

I have the following program

class A {
    static <T> T foo() {
        return null;
    }
}
class Test<T> {
    void bar() {
        T x = A.foo();
    }
}

Actual Behaviour

org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
groovy11.groovy: 9: [Static type checking] - Cannot assign value of type #T to variable of type T
 @ line 9, column 15.
           T x = A.foo();
                 ^1 error

Expected Behaviour

Compile successfully

 

I don't know however, if this is a limitation of the inference engine of groovyc or a bug. Note that the Java compiler compiles the above program successfully. Also note that if I replace "T x = A.foo()" with "String x = A.foo()", groovyc compiles the updated program.

 

Issue Links

• relates to: GROOVY-10342 STC is unable to infer type parameter of parameterized method call