ANTLR Parser Generator Early Access Version 3.0b5 (??, 2006) 1989-2006
error: (10) internal error: T.g : java.lang.NullPointerException
org.antlr.codegen.ActionTranslatorLexer.mDYNAMIC_ABSOLUTE_INDEXED_SCOPE_ATTR(ActionTranslatorLexer.java:1340)
org.antlr.codegen.ActionTranslatorLexer.mTokens(ActionTranslatorLexer.java:2917)
org.antlr.codegen.ActionTranslatorLexer.nextToken(ActionTranslatorLexer.java:217)
org.antlr.codegen.ActionTranslatorLexer.translateToChunks(ActionTranslatorLexer.java:102)
org.antlr.codegen.CodeGenerator.translateAction(CodeGenerator.java:833)
org.antlr.codegen.CodeGenerator.translateActionAttributeReferencesForSingleScope(CodeGenerator.java:502)
org.antlr.codegen.CodeGenerator.translateActionAttributeReferences(CodeGenerator.java:485)
org.antlr.codegen.CodeGenerator.genRecognizer(CodeGenerator.java:323)
org.antlr.Tool.processGrammar(Tool.java:340)
org.antlr.Tool.process(Tool.java:269)
org.antlr.Tool.main(Tool.java:72)

from parsing things like:

block
scope symtab;
@init {
    $block::symbols = new ArrayList();
    level++;
}