FULL PRODUCT VERSION :
java version "1.7.0-ea"
Java(TM) SE Runtime Environment (build 1.7.0-ea-b86)
Java HotSpot(TM) 64-Bit Server VM (build 17.0-b10, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7600]

A DESCRIPTION OF THE PROBLEM :
Code that compiles under Java 6 no longer compiles under the latest Java 7 release.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the test program.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The program should compile.
ACTUAL -
Fails to compile.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Test.java:17: type parameters of <T>T cannot be determined; no unique maximal instance exists for type variable T with upper bounds SpecialKey,K
                        m_key = makeKey(m_key);
                                       ^
  where T,K are type-variables:
    T extends K declared in method <K,T>makeKey(K)
    K extends Key declared in method <K,T>makeKey(K)
Note: Test.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
1 error

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
abstract class Key
{
}

class SpecialKey extends Key
{
}

public class Test
{
private SpecialKey m_key;

public SpecialKey getKey()
{
if (m_key == null)
{
m_key = makeKey(m_key);
}

return m_key;
}

private static <K extends Key, T extends K> T makeKey(K pk)
{
return (T)new SpecialKey();
}
}
---------- END SOURCE ----------

Release Regression From : 6
The above release value was the last known release where this
bug was not reproducible. Since then there has been a regression.