antlr 4.2.2 output to console warning (157)

Question

I downloaded latest release of ANTLR - 4.2.2 (antlr-4.2.2-complete.jar) When I use it to generate parsers for grammar file Java.g4 it prints me some warnings like: "Java.g4:525:16: rule 'expression' contains an 'assoc' terminal option in an unrecognized location"

Files was generated but didn't compile

Previous version works fine.

Whats wrong?

Forepeak

This problem (with the Java.g4 file that comes with the source code zip file for the book The Definitive ANTLR 4 Reference (The Pragmatic Bookshelf, January 2013)) persists, amazingly enough, deep into 2022. There are also pretty ugly lines in the example code and deprecation warnings. That book needs a "revised edition". – Golgi

Answer 1

The <assoc> should now be moved left of the "expression".

It must be placed always right to the surrounding |:

Look here: https://theantlrguy.atlassian.net/wiki/display/ANTLR4/Left-recursive+rules

 ...
 |   expression '&&' expression
    |   expression '||' expression
    |   expression '?' expression ':' expression
    |<assoc=right>   expression
        (   '='
        |   '+='
        |   '-='
        |   '*='
        |   '/='
        |   '&='
        |   '|='
        |   '^='
        |   '>>='
        |   '>>>='
        |   '<<='
        |   '%='
        )
        expression

Moir

and how do you get access to "theantlrguy" ? – Clari

@WeaponX seems it is no longer public – Moir

Maybe it can now be found on GitHub. github.com/antlr/antlr4/blob/master/doc/left-recursion.md – Moir

Confirmed. Search for assoc on this page – Moir