We are experiencing 'java.lang.AssertionError' error while compiling VM
testbase. It does not happen every time but rather often for production
environment - usually at least once per week on nightly clean builds.

Note that we were trying to track it down but without luck -
we always start from clean build (i.e. removing all class files
before any compilation takes place) but error is not reproduced always.
However, it always happens at the same place of building process (see below).

Another note that we observe this error on different platforms.
Last time it happened on Niagara and before we saw it on linux-i586 and
linux-amd64 at very least (so probably bug is platform-independent).

We are using ant to build workspace and ant uses javac API
(it actually uses "com.sun.tools.javac.Main", see below)
instead of executing javac executable.

Here are thesteps how to try to reproduce:

1. login on one of following machines:
   vmsqe-amd-04.russia.sun.com (linux-i586)
   vmsqe-amd-03.russia.sun.com (linux-amd64)
   vmsqe-t2000.russia.sun.com (solaris-sparcv9)

2. cd /set/vmsqe/misc/bugs/javac_1/vm_testbase/vm/ant-build

3. bash build.sh linux-i586 spb classes-all
   or
   bash build.sh linux-amd64 spb classes-all
   or
   bash build.sh solaris-sparc spb classes-all

   build.sh in particular calls 'ant'
   (located in /set/vmsqe/misc/bugs/javac_1/vm_testbase/share/lib/apache-ant-1.6.5)
   and passes the parameters cfg (=linux-i586, ...), cfgset (=spb), target (=classes)

   The full error we get is:

   classes-jdwp:
     [echo] classes: nsk/jdwp
    [javac] Compiling 222 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/classes
    [javac] Note: /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/src/nsk/jdwp/Event/CLASS_UNLOAD/clsunload001/clsunload001.java
            uses or overrides a deprecated API.
    [javac] Note: Recompile with -Xlint:deprecation for details.
    [javac] Compiling 2 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/newclass
     [echo] classes: nsk/jdwp/Method/VariableTable/vartable001
    [javac] Compiling 2 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/classes
     [echo] classes: nsk/jdwp/StackFrame/GetValues/getvalues001
    [javac] Compiling 2 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/classes
     [echo] classes: nsk/jdwp/StackFrame/SetValues/setvalues001
    [javac] Compiling 2 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/classes
     [echo] classes: nsk/jdwp/Method/VariableTableWithGeneric/vartblwithgen001
    [javac] Compiling 2 source files to /net/vmsqe.russia/export1/vmsqe/testbase/builds/testbase_SPB_1.6.0-NIGHTLY/vm/bin/classes

    [javac] An exception has occurred in the compiler (1.6.0-rc). 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.

    [javac] java.lang.AssertionError
    [javac] at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2676)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2616)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2552)
    [javac] at com.sun.tools.javac.comp.Attr.visitClassDef(Attr.java:525)
    [javac] at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:575)
    [javac] at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:360)
    [javac] at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:397)
    [javac] at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2685)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2616)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2552)
    [javac] at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1036)
    [javac] at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:765)
    [javac] at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:730)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:328)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:254)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:245)
    [javac] at com.sun.tools.javac.Main.compile(Main.java:69)
    [javac] at sun.reflect.GeneratedMethodAccessor55.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:589)
    [javac] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:55)
    [javac] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:931)
    [javac] at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:757)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:64)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:378)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:64)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:378)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:64)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:378)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:64)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:378)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:275)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:364)
    [javac] at org.apache.tools.ant.Target.execute(Target.java:341)
    [javac] at org.apache.tools.ant.Target.performTasks(Target.java:369)
    [javac] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1216)
    [javac] at org.apache.tools.ant.Project.executeTarget(Project.java:1185)
    [javac] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:40)
    [javac] at org.apache.tools.ant.Project.executeTargets(Project.java:1068)
    [javac] at org.apache.tools.ant.Main.runBuild(Main.java:668)
    [javac] at org.apache.tools.ant.Main.startAnt(Main.java:187)
    [javac] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:246)
    [javac] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:67)

    The error happens while we are trying to execute 'classes-jdwp' target
    (which is part of "classes-all" target, see vm/ant-build/all.xml).
    The error always happens at this place.

    Once again, note that we use ant without forking
    javac to compile the sources.
    Indeed ant uses "com.sun.tools.javac.Main" to instantiate Javac
    instance. Still, I'd expect javac to be robust in this mode too.

    Here is source code from ant:

    -------------------------------------------------
    public boolean execute() throws BuildException {
        attributes.log("Using modern compiler", Project.MSG_VERBOSE);
        Commandline cmd = setupModernJavacCommand();

        // Use reflection to be able to build on all JDKs >= 1.1:
        try {
            Class c = Class.forName ("com.sun.tools.javac.Main");
            Object compiler = c.newInstance ();
            Method compile = c.getMethod ("compile",
                new Class [] {(new String [] {}).getClass ()});
            int result = ((Integer) compile.invoke
                          (compiler, new Object[] {cmd.getArguments()}))
                .intValue ();
            return (result == MODERN_COMPILER_SUCCESS);
        } catch (Exception ex) {
            if (ex instanceof BuildException) {
                throw (BuildException) ex;
            } else {
                throw new BuildException("Error starting modern compiler",
                                         ex, location);
            }
        }
    }
    -------------------------------------------------

    Looking at this code the only thing that comes to my mind is that javac
    might have some static state and this state eventually gets corrupted.
    However, this does not explain why this problem is not reproducible
    always on the same set of input data files.

    Let me know if you need any more details.

-katya