[GROOVY-7307] Narrower generic type not taken into account when calling another generic method

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4.0, 2.4.1
• Fix Version/s: 2.4.3
• Component/s: Static Type Checker
• Assignee: Cédric Champeau
• Reporter: Frank Pavageau
• Created: 18/Feb/15 07:16
• Updated: 31/Mar/15 06:08
• Resolved: 20/Mar/15 07:17

Description

Given the following class:

@TypeChecked
class A { 
    static <T extends Number> T id(T value) {
        value
    }   

    // Narrower generic type: doesn't compile
    static <T extends Integer> T id2(T value) {
        id(value)
    }   

    // Narrower generic type: doesn't compile either
    static <T extends Integer> T id3(T value) {
        A.<T>id(value)
    }   

    // Fixed type: compiles
    static Integer id4(Integer value) {
        id(value)
    }   
}

id2 and id3 generate compilation errors by the static type checker:

[ERROR] Failed to execute goal org.codehaus.gmavenplus:gmavenplus-plugin:1.3:compile (default) on project generic-return-type: Error occurred while calling a method on a Groovy class from classpath. InvocationTargetException: startup failed: 
[ERROR] /Users/fpavageau/devs/bugs/generic-return-type/src/main/groovy/A.groovy: 26: [Static type checking] - Cannot return value of type T on method returning type T
[ERROR] @ line 26, column 9.
[ERROR] id(value)
[ERROR] ^
[ERROR] 
[ERROR] /Users/fpavageau/devs/bugs/generic-return-type/src/main/groovy/A.groovy: 31: [Static type checking] - Cannot return value of type T on method returning type T
[ERROR] @ line 31, column 9.
[ERROR] A.<T>id(value)
[ERROR] ^
[ERROR] 
[ERROR] 2 errors

I've attached a test case, which is also available on Github. It also contains a Java class (B) doing the same things, but without error.

Issue Links

• relates to: GROOVY-6757 Explicit type hints are not respected