FULL PRODUCT VERSION :
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-b64)
Java HotSpot(TM) Client VM (build 1.5.0-b64, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Linux 2.4.22-1.2199.nptl #1 Wed Aug 4 12:25:07 EDT 2004 i686 athlon i386 GNU/Linux
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
As mentioned on the forums:
http://forum.java.sun.com/thread.jsp?forum=316&thread=563260

The type-safety provided by compile-time warnings can be circumvented through the use of a parameterised method, where the parameter is bound to a raw type.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the provided code, note the lack of any warnings. A String is added to a Collection<Integer>, resulting in a ClassCastException at runtime - exactly the sort of behaviour that the compiler is supposed to catch.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Warnings will always be emitted when type-safety is compromised when no explicit casting is done.
ACTUAL -
There are no warnings for the type-unsafe behaviour described in this report.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Paradoxically, if there were any, this wouldn't be an error.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.*;

public class TypeUnsafe
{
	static public <T extends Collection> void workaround(T a, T b)
	{
		a.addAll(b);
	}

	static public void main(String[] args)
	{
		Collection<Integer> a = new ArrayList<Integer>();
		Collection<String> b = new ArrayList<String>();
		b.add("Bwahahaha");
		workaround(a, b);
		System.out.println(a.iterator().next().intValue()); // ClassCastException
	}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Don't use methods with parameters bound to raw types, or don't trust that you will be warned about type-unsafe behaviour if you do.
###@###.### 10/21/04 17:15 GMT