[antlr-interest] Java.g4 bug? Attrib refs in lexer action

[Graham Wideman]

Hi Ter and all:

I'm working through the examples in the ANTLR 4 book, and have hit a problem using the Java.g4 grammar in example 3.3 ExtractInterfaceTool.

Attempting to generate parser code...
$ antlr4 Java.g4

... results in ...
error(128): Java.g4:670:37: attribute references not allowed in lexer actions: $type
error(128): Java.g4:674:41: attribute references not allowed in lexer actions: $type

In Java.g4 there are rules:

ENUM:   'enum' {if (!enumIsKeyword) $type=Identifier;}
    ;

ASSERT
    :   'assert' {if (!assertIsKeyword) $type=Identifier;}

... which reference $type.

Is there some option that needs to be used for this to work? 

I note that only a few days ago there was discussion thread "Bug in antlr4" discussing the skip vs channel(HIDDEN) issue, but no mention that other users were hitting the problem I report here.

Windows 7
Java 1.7.0_04
ANTLR version: antlr-4.0b2-complete.jar
Java.g4 version dated 2012-09-18, downloaded with example code tpantlr2-code.zip 2012-10-01 16:53

Thanks,

-- Graham