[notes]
This is a regression test for antlr/antlr4#542 "First alternative cannot
be right-associative".  https://github.com/antlr/antlr4/issues/542

[type]
Parser

[grammar]
grammar T;
s @after {<ToStringTree("$ctx"):writeln()>} : e EOF; // must indicate EOF can follow or 'a\<EOF>' won't match
e :\<assoc=right> e '*' e
  |\<assoc=right> e '+' e
  |\<assoc=right> e '?' e ':' e
  |\<assoc=right> e '=' e
  | ID
  ;
ID : 'a'..'z'+ ;
WS : (' '|'\n') -> skip ;

[start]
s

[input]
a?b=c:d

[output]
"""(s (e (e a) ? (e (e b) = (e c)) : (e d)) <EOF>)
"""