class Test {
    // Checking that if one checker finds a Java error
    // and therefor does not set a root, then
    // checkers relying on that checker should also not run.
    // otherwise, it might access a subchecker whose "root" has not been set.
    // (See AnnotatedTypeFactory.setRoot(CompilationUnitTree) )
    void foo() {
        Object a;
        // :: error: variable a is already defined in method foo()
        Object a;
    }
}