Name: rmT116609 Date: 03/25/2004


FULL PRODUCT VERSION :
java version "1.5.0-beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b32c)
Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Windows XP Professional

EXTRA RELEVANT SYSTEM CONFIGURATION :
-source 1.5 is used to compile generic code

A DESCRIPTION OF THE PROBLEM :
When you create a generic method the takes a generic type and an array type the compiler allows you to call with two different types. Best in code.

public static <Var> void transferBug(Var[] from, Collection<Var> to){
       to.add(from[0]);
}

The above method can be called with this snippet.

Object[] objArray = {new Object()};
ArrayList<String> strList = new ArrayList<String>();
transferBug(a, strList);

Which results in an Object in an ArrayList designed to only hold strings
Continuing the code this would cause a Class cast exception, but not be noted on compile.

String str = strList.get(0);


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run the sample code provided

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Shoud the compiler generate an error like the following.

<Var>transferBug(Var[], java.util.ArrayList<Var>)
cannot be applied to (java.lang.Object,java.util.ArrayList<java.lang.String>)
; no instance(s) of type variable(s) Var exist so that argument type java.util.ArrayList<java.lang.S
tring> conforms to formal parameter type Object


ACTUAL -
With the error in place it will compile and generate the following exception

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.ClassCastException: java.lang.Object
        at BugDemo.main(BugDemo.java:11)


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.ArrayList;
import java.util.Collection;

public class BugDemo{

    public static void main(String[] args){
        Object[] objArray = {new Object()};
        ArrayList<String> strList = new ArrayList<String>();
        transferBug(objArray, strList);
        String str = strList.get(0);
}

public static <Var> void transferBug(Var[] from, Collection<Var> to){
    to.add(from[0]);
}
}
---------- END SOURCE ----------
(Incident Review ID: 244871)
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