I got the following during a build:

CLASSPATH=. /bin/javac -nowarn -d . Revision.java
java.lang.NullPointerException
at sun.tools.java.MethodSet.lookupSig(Compiled Code)
at sun.tools.java.ClassDefinition.collectOneClass(Compiled Code)
at sun.tools.java.ClassDefinition.collectInheritedMethods(Compiled Code)
at sun.tools.java.BinaryClass.basicCheck(Compiled Code)
at sun.tools.java.ClassDeclaration.getClassDefinition(Compiled Code)
at sun.tools.java.Environment.getQualifiedClassDefinition(Compiled Code)
at sun.tools.java.Environment.resolve(Compiled Code)
at sun.tools.tree.IdentifierExpression.toResolvedType(IdentifierExpression.java:312)
at sun.tools.tree.IdentifierExpression.checkAmbigName(Compiled Code)
at sun.tools.tree.MethodExpression.checkValue(Compiled Code)
at sun.tools.tree.MethodExpression.check(MethodExpression.java:575)
at sun.tools.tree.ExpressionStatement.check(Compiled Code)
at sun.tools.tree.Statement.checkBlockStatement(Compiled Code)
at sun.tools.tree.CompoundStatement.check(Compiled Code)
at sun.tools.tree.Statement.checkMethod(Statement.java:92)
at sun.tools.javac.SourceMember.check(Compiled Code)
at sun.tools.javac.SourceClass.checkMembers(Compiled Code)
at sun.tools.javac.SourceClass.checkInternal(Compiled Code)
at sun.tools.javac.SourceClass.check(SourceClass.java:511)
at sun.tools.javac.Main.compile(Compiled Code)
at sun.tools.javac.Main.main(Main.java:733)
error: An exception has occurred in the compiler; please file a bug report (http://java.sun.com/cgi-bin/bugreport.cgi).

simmonmt @ install-bldx: java -fullversion
java full version "Solaris_JDK_1.2.1_03_pre_SC50"
simmonmt @ install-bldx: uname -a
SunOS install-bldx 5.8 s28_24 i86pc i386 i86pc
simmonmt @ install-bldx: cat /etc/release
                              Solaris 8 s28_24 INTEL
           Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
                             Assembled 01 June 1999

See /ws/admininstall-28-gate/src/bundled/app/webstart/prodreg.