anchor.diff:  assignmentExpression
       :   conditionalExpression
       |   unaryExpression assignmentOperator assignmentExpression
  +    |   DigitSequence // for
       ;
   
   assignmentOperator
  
positive.code:     :   unaryExpression
      |   '(' typeName ')' castExpression
      |   '__extension__' '(' typeName ')' castExpression
      ;
  
  multiplicativeExpression
  
negative.code:     |   directDeclarator '[' typeQualifierList? '*' ']'
      |   directDeclarator '(' parameterTypeList ')'
      |   directDeclarator '(' identifierList? ')'
      |   Identifier ':' DigitSequence  // bit field
      ;
  
  gccDeclaratorExtension
  