I'm using JDK 6, IntelliJ 7.0.4 build 7962, ANTLR 3.1.1, and the latest ANTLRWorks plug-in to work through a copy of the Pragmatic "Definitive ANTLR".
When I get to section 3.3, 'Evaluating Expressions Using An AST Intermediate Form', ANTLRWorks fails me. I get a pop-up that says "cannot find tokens file <unset-dir>\Expr.tokens" whenever I try to generate code.
When I ran org.antlr.Tools on the command line, I found out about the -lib parameter. I tried setting that in ANTLRWorks, but it still couldn't find the .tokens file.
When I generated code on the command line without ANTLRWorks, all was well. It appears that ANTLRWorks is not using the ANTLR options properly.