[antlr-interest] Decision can match input such as "'*'" using multiple alternatives: 1, 2

[Sergei Politov]

Hello,

  I'm new to ANTLR. I tried to port my grammar from Boost.Spirit to ANTLR
and faced the following warning:
Decision can match input such as "'*'" using multiple alternatives: 1, 2

  I made a minimal grammar to reproduce it (also in attach):
======================
grammar X ;

s : e EOF ;
e : t ;
t : f ('*' f)* ;
f : NUM | '-' e ;

NUM : '0'..'9'+ ;
======================

  Really I don't understand the described issue.
  I don't know input that could match in multiple ways.

  Please clarify the situation.

Best Regards,
  Sergey
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