ANTLR v3 Test case for an error in syntactic predicate backtracking

footer.g

grammar footer;
options {
    language=Python;
    output=AST;
}

header_file
  : header_element+
  ;

header_element
  : (COMMENT function_prototype)=> foo=documented_function
  | COMMENT
  | bar=function_prototype
  ;

documented_function
  : COMMENT function_prototype
  ;

function_prototype
  : IDENTIFIER
  ;

IDENTIFIER : LETTER (LETTER|'0'..'9')* ;
fragment LETTER : '$' | 'A'..'Z' | 'a'..'z' | '_' ;

COMMENT : '/*' (options {greedy=false;} : .)* '*/' ;

WS : (' '|'\r'|'\t'|'\u000C'|'\n') {$channel=HIDDEN;} ;