[antlr-interest] Potential gotcha - could it be warned?

[Gavin Lambert]

At 23:10 25/11/2007, Steve Bennett wrote:
 >I just spent the last hour tracking down one stupid error in my
 >code:
 >a rule that looked like this:
 >
 >foo:  (| bar);
 >
 >It was enough to make the debugger fail on any input, and go 
into
 >an infinite loop upon pressing the "back" button.
 >
 >Perhaps ANTLRWorks could detect this kind of rule and either 
warn
 >or refuse to compile?

That's a valid construct, though.  It's essentially identical to:
   foo: bar?;

(Now, if you used that as the only contents of a loop, you'd have 
a problem.)