anchor.diff:  assignmentExpression
       :   conditionalExpression
       |   unaryExpression assignmentOperator assignmentExpression
  +    |   DigitSequence // for
       ;
   
   assignmentOperator
  
positive.code:     ;
  
  iterationStatement
      :   'while' '(' expression ')' statement
      |   'do' statement 'while' '(' expression ')' ';'
      |   'for' '(' expression? ';' expression? ';' expression? ')' statement
      |   'for' '(' declaration expression? ';' expression? ')' statement
      ;
  
  jumpStatement
  
negative.code:     |   directDeclarator '[' typeQualifierList? '*' ']'
      |   directDeclarator '(' parameterTypeList ')'
      |   directDeclarator '(' identifierList? ')'
      |   Identifier ':' DigitSequence  // bit field
      ;
  
  gccDeclaratorExtension
  