FULL PRODUCT VERSION :
java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) Server VM (build 19.1-b02, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux 2.6.18-238.5.1.el5 #1 SMP Mon Feb 21 05:53:18 EST 2011 i686 i686 i386 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
I compiled the following program. Instead of compiling, javac aborted with the following stack dump.

===program===
public class Boom {
    Object a[];
    Object o = (a = null)[0];
}
===end===
===shell command and output===
javac Boom.java
An exception has occurred in the compiler (1.6.0_24). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
at com.sun.tools.javac.code.Types.erasure(Types.java:1490)
at com.sun.tools.javac.jvm.Code.emitop0(Code.java:455)
at com.sun.tools.javac.jvm.Items$IndexedItem.load(Items.java:305)
at com.sun.tools.javac.jvm.Gen.visitAssign(Gen.java:1752)
at com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:1342)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:818)
at com.sun.tools.javac.jvm.Gen.visitExec(Gen.java:1605)
at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1074)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:686)
at com.sun.tools.javac.jvm.Gen.genStats(Gen.java:737)
at com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1013)
at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:893)
at com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:866)
at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:639)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2198)
at com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:617)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1289)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1259)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
at com.sun.tools.javac.main.Main.compile(Main.java:353)
at com.sun.tools.javac.main.Main.compile(Main.java:279)
at com.sun.tools.javac.main.Main.compile(Main.java:270)
at com.sun.tools.javac.Main.compile(Main.java:69)
at com.sun.tools.javac.Main.main(Main.java:54)


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
$ cat > Boom.java
public class Boom {
    Object a[];
    Object o = (a = null)[0];
}
^D

$ javac Boom.java

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Javac compiles my program.
ACTUAL -
Javac aborted with a stack dump.


ERROR MESSAGES/STACK TRACES THAT OCCUR :
An exception has occurred in the compiler (1.6.0_24). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.NullPointerException
at com.sun.tools.javac.code.Types.erasure(Types.java:1490)
at com.sun.tools.javac.jvm.Code.emitop0(Code.java:455)
at com.sun.tools.javac.jvm.Items$IndexedItem.load(Items.java:305)
at com.sun.tools.javac.jvm.Gen.visitAssign(Gen.java:1752)
at com.sun.tools.javac.tree.JCTree$JCAssign.accept(JCTree.java:1342)
at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:818)
at com.sun.tools.javac.jvm.Gen.visitExec(Gen.java:1605)
at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1074)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:686)
at com.sun.tools.javac.jvm.Gen.genStats(Gen.java:737)
at com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:1013)
at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:739)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:700)
at com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:893)
at com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:866)
at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:639)
at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:665)
at com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2198)
at com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:617)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1289)
at com.sun.tools.javac.main.JavaCompiler.generate(JavaCompiler.java:1259)
at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
at com.sun.tools.javac.main.Main.compile(Main.java:353)
at com.sun.tools.javac.main.Main.compile(Main.java:279)
at com.sun.tools.javac.main.Main.compile(Main.java:270)
at com.sun.tools.javac.Main.compile(Main.java:69)
at com.sun.tools.javac.Main.main(Main.java:54)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
public class Boom {
    Object a[];
    Object o = (a = null)[0];
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Don't write such a silly program.