FULL PRODUCT VERSION :
javac 1.6.0_11
javac 1.6.0_12

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Wersja 6.0.6001]  - Microsoft Vista,
Linux 32-bit

A DESCRIPTION OF THE PROBLEM :
Compilation of the attached test case results in a java.lang.VerifyError. This is due to a bad compilation of the class (see expected and actual results).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile the attached test case. Run the test case. Observe the error. Decompile the .class file to get the bad bytecode.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Expected bytecode:

> javap -c test.Test

Compiled from "Test.java"
public class test.Test extends java.lang.Object{
public test.Test();
  Code:
   0:   aload_0
   1:   invokespecial   #8; //Method java/lang/Object."<init>":()V
   4:   return

public static void main(java.lang.String[]);
  Code:
   0:   iconst_0
   1:   istore_2
   2:   iconst_0
   3:   invokestatic    #16; //Method java/lang/Byte.valueOf:(B)Ljava/lang/Byte;
   6:   astore_1
   7:   return

}

0 is assigned to 'fi' (lines 0-1 of main()) but later a constant 0 is used for assignment to 'B' (by means of Byte.valueOf() method) as 'fi' is a compile-time constant and should be inlined.
ACTUAL -
Actual bytecode:

> javap -c test.Test

Compiled from "Test.java"
public class test.Test extends java.lang.Object{
public test.Test();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return

public static void main(java.lang.String[]);
  Code:
   0:   iload_2
   1:   i2b
   2:   invokestatic    #2; //Method java/lang/Byte.valueOf:(B)Ljava/lang/Byte;
   5:   astore_1
   6:   return

}

in line 0 of the main() method the code tries lo load a local integer variable #2 ('fi'). But there is no initialisation of that variable. The whole main() method is reduced to the 'B=fi;' assignment, but neither the constant 0 value is used nor is 'fi' initialised with 0 previously.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
> java test.Test

Exception in thread "main" java.lang.VerifyError: (class: test/Test, method: main signature: ([Ljava/lang/String;)V) Accessing value from uninitialized register 2
Could not find the main class: test.Test.  Program will exit.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package test;
 
public class Test {
 
	public static void main(String[] args) {
		Byte B;
		final int fi = 0;
		B = fi; // narrowing pri. (int -> byte) + boxing (byte -> Byte)
	}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Assignment in two steps solves the case.

class Test {
 public static void main(String[] args) {
  final int fi = 0;
  byte b = fi; // int -> byte
  Byte B = b;  // byte -> Byte
 }
}