GWT - Error constructing Java AST

Question

What could possibly be causing this error during compilation?

I have generated project from this archetype https://github.com/ArcBees/Arcbees-Archetypes and I have changed only thing - update GWT to 2.8.0 and GWTP to 1.5.3.

[INFO] [ERROR] An internal compiler exception occurred
[INFO] com.google.gwt.dev.jjs.InternalCompilerException: Error constructing Java AST
[INFO]  at com.google.gwt.dev.jjs.impl.GwtAstBuilder.translateException(GwtAstBuilder.java:3099)
[INFO]  at com.google.gwt.dev.jjs.impl.GwtAstBuilder$AstVisitor.endVisit(GwtAstBuilder.java:352)
[INFO]  at org.eclipse.jdt.internal.compiler.ast.AllocationExpression.traverse(AllocationExpression.java:670)
[INFO]  at org.eclipse.jdt.internal.compiler.ast.Assignment.traverse(Assignment.java:260)
[INFO]  at org.eclipse.jdt.internal.compiler.ast.MethodDeclaration.traverse(MethodDeclaration.java:347)
[INFO]  at org.eclipse.jdt.internal.compiler.ast.TypeDeclaration.traverse(TypeDeclaration.java:1379)
[INFO]  at com.google.gwt.dev.jjs.impl.GwtAstBuilder.process(GwtAstBuilder.java:3058)
[INFO]  at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater$UnitProcessorImpl.process(CompilationStateBuilder.java:141)
[INFO]  at com.google.gwt.dev.javac.JdtCompiler$CompilerImpl.process(JdtCompiler.java:384)
[INFO]  at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:470)
[INFO]  at com.google.gwt.dev.javac.JdtCompiler.doCompile(JdtCompiler.java:985)
[INFO]  at com.google.gwt.dev.javac.CompilationStateBuilder$CompileMoreLater.compile(CompilationStateBuilder.java:339)
[INFO]  at com.google.gwt.dev.javac.CompilationStateBuilder.doBuildFrom(CompilationStateBuilder.java:580)
[INFO]  at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:513)
[INFO]  at com.google.gwt.dev.javac.CompilationStateBuilder.buildFrom(CompilationStateBuilder.java:499)
[INFO]  at com.google.gwt.dev.cfg.ModuleDef.getCompilationState(ModuleDef.java:668)
[INFO]  at com.google.gwt.dev.Precompile.precompile(Precompile.java:255)
[INFO]  at com.google.gwt.dev.Precompile.precompile(Precompile.java:229)
[INFO]  at com.google.gwt.dev.Precompile.precompile(Precompile.java:145)
[INFO]  at com.google.gwt.dev.Compiler.run(Compiler.java:206)
[INFO]  at com.google.gwt.dev.Compiler.run(Compiler.java:158)
[INFO]  at com.google.gwt.dev.Compiler$1.run(Compiler.java:120)
[INFO]  at com.google.gwt.dev.CompileTaskRunner.doRun(CompileTaskRunner.java:55)
[INFO]  at com.google.gwt.dev.CompileTaskRunner.runWithAppropriateLogger(CompileTaskRunner.java:50)
[INFO]  at com.google.gwt.dev.Compiler.main(Compiler.java:127)
[INFO] Caused by: java.lang.NullPointerException
[INFO]  at com.google.gwt.dev.jjs.impl.ReferenceMapper.get(ReferenceMapper.java:99)
[INFO]  at com.google.gwt.dev.jjs.impl.GwtAstBuilder$AstVisitor.pushNewExpression(GwtAstBuilder.java:2642)
[INFO]  at com.google.gwt.dev.jjs.impl.GwtAstBuilder$AstVisitor.endVisit(GwtAstBuilder.java:350)
[INFO]  ... 23 more
[INFO]    [ERROR] at AbstractStringBuilder.java(137): new String(buffer)
[INFO]       org.eclipse.jdt.internal.compiler.ast.AllocationExpression
[INFO] Shutting down PersistentUnitCache thread

Answer 1

The pom.xml generated GWTP archetype has an implicit dependency to gwt-dev-2.7.0, resulting in a version mismatch. Try adding an explicit dependency to 2.8.0:

    <dependency>
        <groupId>com.google.gwt</groupId>
        <artifactId>gwt-dev</artifactId>
        <version>2.8.0</version>
        <scope>provided</scope>
    </dependency>

Answer 2

A few years late, but I just ran into the same issue.

Got the same exception when trying to run GWT in Super Dev mode after adding Tomcat runtime to another project in my Eclipse workspace. Adding a Tomcat Server to one of the projects will likely add it to other projects (Eclipse Bug) and this may cause dependency issues.

To resolve it: Remove Tomcat dependency from all related projects build path, clean and rebuild.