Given a rule like:

rule "test case"
when
Number() from accumulate(
not Number(),
init( double total = 0; ),
action( ),
reverse( ),
result( new Double( total ) )
)
then
// no op
end

the following exception is thrown:

java.lang.ClassCastException: org.drools.compiler.lang.descr.NotDescr cannot be cast to org.drools.compiler.lang.descr.PatternDescr
at org.drools.compiler.lang.descr.AccumulateDescr.getInputPattern(AccumulateDescr.java:194)
at org.drools.compiler.rule.builder.util.PackageBuilderUtil.isReadLocalsFromTuple(PackageBuilderUtil.java:21)
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.build(JavaAccumulateBuilder.java:93)
at org.drools.compiler.rule.builder.dialect.java.JavaAccumulateBuilder.build(JavaAccumulateBuilder.java:66)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:320)
at org.drools.compiler.rule.builder.PatternBuilder.build(PatternBuilder.java:138)
at org.drools.compiler.rule.builder.GroupElementBuilder.build(GroupElementBuilder.java:66)
at org.drools.compiler.rule.builder.RuleBuilder.build(RuleBuilder.java:89)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.addRule(KnowledgeBuilderImpl.java:1652)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileRules(KnowledgeBuilderImpl.java:968)
at org.drools.compiler.builder.impl.KnowledgeBuilderImpl.compileAllRules(KnowledgeBuilderImpl.java:844)
at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.buildRules(CompositeKnowledgeBuilderImpl.java:279)
at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.buildPackages(CompositeKnowledgeBuilderImpl.java:103)
at org.drools.compiler.builder.impl.CompositeKnowledgeBuilderImpl.build(CompositeKnowledgeBuilderImpl.java:91)
at org.drools.compiler.kie.builder.impl.AbstractKieModule.buildKnowledgePackages(AbstractKieModule.java:220)
at org.drools.compiler.kie.builder.impl.AbstractKieProject.verify(AbstractKieProject.java:43)
at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildKieProject(KieBuilderImpl.java:208)
at org.drools.compiler.kie.builder.impl.KieBuilderImpl.buildAll(KieBuilderImpl.java:177)
at regressions.DroolsCompilerBugTest.bug(DroolsCompilerBugTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)