FULL PRODUCT VERSION :
Reproduced on all recent versions. Tested most recently on 1.6.0_18

ADDITIONAL OS VERSION INFORMATION :
Windows 7 Enterprise 64-bit

A DESCRIPTION OF THE PROBLEM :
// Compiling the following causes a javac crash.

interface I<T> {}

interface A<T> extends I<A<A<T>>>{}

abstract class X {
    abstract <T> T foo(T x, T y);
    void bar(A<Integer> x, A<String> y){
        foo(x, y);
    }
}

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
compile the program appearing in the description

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Compiler produces an intelligible diagnostic about problematic inheritance hierarchy
ACTUAL -
javac consumes huge amounts of processing time and memory and finally crashes.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
interface I<T> {}

interface A<T> extends I<A<A<T>>>{}

abstract class X {
    abstract <T> T foo(T x, T y);
    void bar(A<Integer> x, A<String> y){
        foo(x, y);
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Write a program that doesn't crash javac.