public boolean grammarSymbolCausesIssueInGeneratedCode(GrammarAST idNode) {
		switch (idNode.getParent().getType()) {
			case ANTLRParser.ASSIGN:
				switch (idNode.getParent().getParent().getType()) {
					case ANTLRParser.ELEMENT_OPTIONS:
					case ANTLRParser.OPTIONS:
						return false;

					default:
						break;
				}

				break;

			case ANTLRParser.AT:
			case ANTLRParser.ELEMENT_OPTIONS:
				return false;

			case ANTLRParser.LEXER_ACTION_CALL:
				if (idNode.getChildIndex() == 0) {
					// first child is the command name which is part of the ANTLR language
					return false;
				}

				// arguments to the command should be checked
				break;

			default:
				break;
		}

		return getReservedWords().contains(idNode.getText());
	}
How many bits should be used to do inline token type tests? Java assumes
 a 64-bit word for bitsets.  Must be a valid wordsize for your target like
 8, 16, 32, 64, etc...

 @since 4.5
tool/src/org/antlr/v4/codegen/Target.java