I created a demo project here: https://github.com/confile/Realtime-JSON-Test
It compile with GWT compile without any problems from Eclipse. When I run the app in SuperDevMode the first compile failed with the following errors: Compiling 1 permutation Compiling permutation 0... [ERROR] An internal compiler exception occurred com.google.gwt.dev.jjs.InternalCompilerException: Unexpected error during visit. at com.google.gwt.dev.jjs.ast.JVisitor.translateException(JVisitor.java:121) at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:140) at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:132) at com.google.gwt.dev.jjs.impl.Devirtualizer.getStaticImpl(Devirtualizer.java:562) at com.google.gwt.dev.jjs.impl.Devirtualizer.access$400(Devirtualizer.java:75) at com.google.gwt.dev.jjs.impl.Devirtualizer$RewriteVirtualDispatches.ensureDevirtualVersionExists(Devirtualizer.java:184) at com.google.gwt.dev.jjs.impl.Devirtualizer$RewriteVirtualDispatches.endVisit(Devirtualizer.java:101) at com.google.gwt.dev.jjs.ast.JMethod.traverse(JMethod.java:580) at com.google.gwt.dev.jjs.ast.JModVisitor$ListContextImmutable.traverse(JModVisitor.java:183) at com.google.gwt.dev.jjs.ast.JModVisitor.acceptWithInsertRemoveImmutable(JModVisitor.java:355) at com.google.gwt.dev.jjs.ast.JInterfaceType.traverse(JInterfaceType.java:75) at com.google.gwt.dev.jjs.ast.JModVisitor.traverse(JModVisitor.java:380) at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:292) at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:284) at com.google.gwt.dev.jjs.ast.JProgram.visitModuleTypes(JProgram.java:1192) at com.google.gwt.dev.jjs.ast.JProgram.traverse(JProgram.java:1156) at com.google.gwt.dev.jjs.ast.JModVisitor.traverse(JModVisitor.java:380) at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:292) at com.google.gwt.dev.jjs.ast.JModVisitor.accept(JModVisitor.java:284) at com.google.gwt.dev.jjs.impl.Devirtualizer.execImpl(Devirtualizer.java:320) at com.google.gwt.dev.jjs.impl.Devirtualizer.exec(Devirtualizer.java:218) at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler$MonolithicPermutationCompiler.normalizeSemantics(MonolithicJavaToJavaScriptCompiler.java:95) at com.google.gwt.dev.jjs.JavaToJavaScriptCompiler$PermutationCompiler.compilePermutation(JavaToJavaScriptCompiler.java:290) at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler.compilePermutation(MonolithicJavaToJavaScriptCompiler.java:296) at com.google.gwt.dev.jjs.UnifiedAst.compilePermutation(UnifiedAst.java:143) at com.google.gwt.dev.CompilePerms.compile(CompilePerms.java:197) at com.google.gwt.dev.ThreadedPermutationWorkerFactory$ThreadedPermutationWorker.compile(ThreadedPermutationWorkerFactory.java:50) at com.google.gwt.dev.PermutationWorkerFactory$Manager$WorkerThread.run(PermutationWorkerFactory.java:74) at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.NullPointerException at com.google.gwt.dev.jjs.ast.JVisitor.accept(JVisitor.java:137) ... 27 more [ERROR] <no source info>: <source info not available> [ERROR] at JsonElement.java(19): public abstract JsonElement clear(); com.google.gwt.dev.jjs.ast.JMethod [ERROR] at JsonElement.java(18): interface JsonElement extends Serializable com.google.gwt.dev.jjs.ast.JInterfaceType [ERROR] at Unknown(0): <JProgram> com.google.gwt.dev.jjs.ast.JProgram [ERROR] Unrecoverable exception, shutting down com.google.gwt.core.ext.UnableToCompleteException: (see previous log entries) at com.google.gwt.dev.javac.CompilationProblemReporter.logAndTranslateException(CompilationProblemReporter.java:106) at com.google.gwt.dev.jjs.JavaToJavaScriptCompiler$PermutationCompiler.compilePermutation(JavaToJavaScriptCompiler.java:367) at com.google.gwt.dev.jjs.MonolithicJavaToJavaScriptCompiler.compilePermutation(MonolithicJavaToJavaScriptCompiler.java:296) at com.google.gwt.dev.jjs.UnifiedAst.compilePermutation(UnifiedAst.java:143) at com.google.gwt.dev.CompilePerms.compile(CompilePerms.java:197) at com.google.gwt.dev.ThreadedPermutationWorkerFactory$ThreadedPermutationWorker.compile(ThreadedPermutationWorkerFactory.java:50) at com.google.gwt.dev.PermutationWorkerFactory$Manager$WorkerThread.run(PermutationWorkerFactory.java:74) at java.lang.Thread.run(Thread.java:745) [ERROR] Not all permutation were compiled , completed (0/1) [WARN] recompile failed [WARN] continuing to serve previous version The library uses the *<super-source path="super" />* tag. From the GWT documentation I found ( http://www.gwtproject.org/doc/latest/DevGuideOrganizingProjects.html) " In development mode, the native JRE classes always supercede classes compiled from source." This is a problem because I cannot use the lib in SuperDevMode. *Is there any way to fix this?* -- You received this message because you are subscribed to the Google Groups "GWT Contributors" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit-contributors+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/google-web-toolkit-contributors/ac0446bb-1db6-49ea-bc6a-817810d15b9b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.