[GROOVY-10371] STC involves improper subtyping rules for parameterized types with wildcard types

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 5.0.0-alpha-12
• Component/s: Static Type Checker

Language

groovy

• Assignee: Eric Milles
• Reporter: Thodoris Sotiropoulos
• Created: 16/Nov/21 15:27
• Updated: 13/Nov/24 13:37
• Resolved: 13/Nov/24 13:37

Description

The following program should not type check

class A<T> {}

class B<T> extends A<T> {}

class Test {
  B<? extends Number> x = new B<Double>();
  A<Number> y = x;
}

Expected behaviour

the compiler should have rejected the program and produced an error of the form (like javac does):

 error: incompatible types: B<CAP#1> cannot be converted to A<Number>
  A<Number> y = x;
                ^
  where CAP#1 is a fresh type-variable:
    CAP#1 extends Number from capture of ? extends Number
1 error

Tested against master

Issue Links

• is related to: GROOVY-9074 CompileStatic does not throw expected exception