FULL PRODUCT VERSION :
java version "1.6.0_26"
Java(TM) SE Runtime Environment (build 1.6.0_26-b03)
Java HotSpot(TM) Client VM (build 20.1-b02, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows 7 x64

A DESCRIPTION OF THE PROBLEM :
C:\netspace\guava-libraries-read-only>ant
Buildfile: C:\netspace\guava-libraries-read-only\build.xml

compile:
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] Compiling 201 source files to C:\netspace\guava-libraries-read-only\build\classes
    [javac] An exception has occurred in the compiler (1.6.0_26). Please file a bug at the Java Developer Connection (http://java.sun.com/we
bapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you
.
    [javac] java.lang.NullPointerException
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleConcretes(Check.java:1215)
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleSupertypes(Check.java:1567)
    [javac] at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2674)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2628)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2564)
    [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:353)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:279)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:270)
    [javac] at com.sun.tools.javac.Main.compile(Main.java:69)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:56)
    [javac] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1134)
    [javac] at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.Target.execute(Target.java:390)
    [javac] at org.apache.tools.ant.Target.performTasks(Target.java:411)
    [javac] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    [javac] at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    [javac] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    [javac] at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    [javac] at org.apache.tools.ant.Main.runBuild(Main.java:809)
    [javac] at org.apache.tools.ant.Main.startAnt(Main.java:217)
    [javac] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
    [javac] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)

BUILD FAILED
C:\netspace\guava-libraries-read-only\build.xml:61: The following error occurred while executing this line:
C:\netspace\guava-libraries-read-only\build.xml:329: Compile failed; see the compiler error output for details.

  Total time: 5 seconds


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
checkout guava from svn
ant


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
successful build
ACTUAL -
C:\netspace\guava-libraries-read-only>ant
Buildfile: C:\netspace\guava-libraries-read-only\build.xml

compile:
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] Compiling 201 source files to C:\netspace\guava-libraries-read-only\build\classes
    [javac] An exception has occurred in the compiler (1.6.0_26). Please file a bug at the Java Developer Connection (http://java.sun.com/we
bapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you
.
    [javac] java.lang.NullPointerException
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleConcretes(Check.java:1215)
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleSupertypes(Check.java:1567)
    [javac] at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2674)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2628)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2564)
    [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:353)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:279)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:270)
    [javac] at com.sun.tools.javac.Main.compile(Main.java:69)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:56)
    [javac] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1134)
    [javac] at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.Target.execute(Target.java:390)
    [javac] at org.apache.tools.ant.Target.performTasks(Target.java:411)
    [javac] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    [javac] at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    [javac] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    [javac] at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    [javac] at org.apache.tools.ant.Main.runBuild(Main.java:809)
    [javac] at org.apache.tools.ant.Main.startAnt(Main.java:217)
    [javac] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
    [javac] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)

BUILD FAILED
C:\netspace\guava-libraries-read-only\build.xml:61: The following error occurred while executing this line:
C:\netspace\guava-libraries-read-only\build.xml:329: Compile failed; see the compiler error output for details.

  Total time: 5 seconds


ERROR MESSAGES/STACK TRACES THAT OCCUR :
C:\netspace\guava-libraries-read-only>ant
Buildfile: C:\netspace\guava-libraries-read-only\build.xml

compile:
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] C:\netspace\guava-libraries-read-only\build.xml:329: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=
last; set to false for repeatable builds
    [javac] Compiling 201 source files to C:\netspace\guava-libraries-read-only\build\classes
    [javac] An exception has occurred in the compiler (1.6.0_26). Please file a bug at the Java Developer Connection (http://java.sun.com/we
bapps/bugreport) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you
.
    [javac] java.lang.NullPointerException
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleConcretes(Check.java:1215)
    [javac] at com.sun.tools.javac.comp.Check.checkCompatibleSupertypes(Check.java:1567)
    [javac] at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:2674)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2628)
    [javac] at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:2564)
    [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:353)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:279)
    [javac] at com.sun.tools.javac.main.Main.compile(Main.java:270)
    [javac] at com.sun.tools.javac.Main.compile(Main.java:69)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    [javac] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.taskdefs.compilers.Javac13.execute(Javac13.java:56)
    [javac] at org.apache.tools.ant.taskdefs.Javac.compile(Javac.java:1134)
    [javac] at org.apache.tools.ant.taskdefs.Javac.execute(Javac.java:912)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.Sequential.execute(Sequential.java:68)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.taskdefs.MacroInstance.execute(MacroInstance.java:398)
    [javac] at org.apache.tools.ant.UnknownElement.execute(UnknownElement.java:291)
    [javac] at sun.reflect.GeneratedMethodAccessor4.invoke(Unknown Source)
    [javac] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [javac] at java.lang.reflect.Method.invoke(Method.java:597)
    [javac] at org.apache.tools.ant.dispatch.DispatchUtils.execute(DispatchUtils.java:106)
    [javac] at org.apache.tools.ant.Task.perform(Task.java:348)
    [javac] at org.apache.tools.ant.Target.execute(Target.java:390)
    [javac] at org.apache.tools.ant.Target.performTasks(Target.java:411)
    [javac] at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1399)
    [javac] at org.apache.tools.ant.Project.executeTarget(Project.java:1368)
    [javac] at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
    [javac] at org.apache.tools.ant.Project.executeTargets(Project.java:1251)
    [javac] at org.apache.tools.ant.Main.runBuild(Main.java:809)
    [javac] at org.apache.tools.ant.Main.startAnt(Main.java:217)
    [javac] at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
    [javac] at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)

BUILD FAILED
C:\netspace\guava-libraries-read-only\build.xml:61: The following error occurred while executing this line:
C:\netspace\guava-libraries-read-only\build.xml:329: Compile failed; see the compiler error output for details.

  Total time: 5 seconds


REPRODUCIBILITY :
This bug can be reproduced always.