Name: nt126004 Date: 09/20/2002


FULL PRODUCT VERSION :
java version "1.4.0-beta3"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-beta3-b84)
Java HotSpot(TM) Client VM (build 1.4.0-beta3-b84, mixed mode)


FULL OPERATING SYSTEM VERSION :

glibc-2.2.4-19.3
Linux quaffle 2.4.9-31smp #1 SMP Tue Feb 26 06:55:00 EST
2002 i686 unknown
/etc/redhat-release

ADDITIONAL OPERATING SYSTEMS :

The bug is OS independent, so all systems are affected

A DESCRIPTION OF THE PROBLEM :
The Javac compiler fails to correctly compile switch
  statements. As a result, the class files either have
VerifyErrors, of variables are lost because of cross-scoping
issues.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. `javac Foo.java`
2. `java Foo`
3. `java Bar a b`

EXPECTED VERSUS ACTUAL BEHAVIOR :
Step 1. Compilation should and does succeed - both classes
are legal: even though the declaration of i occurs in dead
code (as evidenced by the fact that the initializer
expression is not even emitted in bytecode), i is in scope
for case 2.

Step 2. Actual results should be similar to
"[Ljava.lang.String;@3f5d07", not "Exception in thread
"main" java.lang.VerifyError: (class: Foo, method: main
signature: ([Ljava/lang/String;)V) Accessing value from
uninitialized register 0".

Step 3. Actual results should be similar to
"[Ljava.lang.String;@3f5d07", not "2".

I think the bug is occuring because i is declared in a dead
code region. The compiler is not properly assigning it a
unique local variable number, but is using slot 0 instead.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
Exception in thread "main" java.lang.VerifyError: (class: Foo, method: main
signature: ([Ljava/lang/String;)V) Accessing value from uninitialized register 0

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
class Foo {
   public static void main(String[] args) {
     switch (args.length) {
     case 1:
       if (true)
         return;
       int i = 1;
     case 2:
       i = 2;
     }
     System.out.println(args);
   }
}

class Bar {
  public static void main(String[] args) {
    switch (args.length) {
    case 1:
      if (true)
        return;
      Object i = "1";
    case 2:
      i = "2";
    }
    System.out.println(args);
  }
}

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

CUSTOMER WORKAROUND :
Do not declare variables in dead code regions of switch
blocks.
(Review ID: 153809)
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