anchor.diff:  
   blockItem
       :   statement
  -    |   declaration
  +//    |   declaration
       ;
   
   expressionStatement
  
positive.code:     :   Identifier
      ;
  
  declarator
      :   directDeclarator
      ;
  
  directDeclarator
      :   Identifier
      |   '(' declarator ')'
      |   directDeclarator '(' parameterTypeList ')'
      |   directDeclarator '(' identifierList? ')'
      |   Identifier ':' DigitSequence  // bit field
      ;
  
  parameterTypeList
      :   parameterList
      |   parameterList ',' '...'
      ;
  
  parameterList
      :   parameterDeclaration
      |   parameterList ',' parameterDeclaration
      ;
  
  parameterDeclaration
      :   declarationSpecifiers declarator
      ;
  
  identifierList
      :   Identifier
  
negative.code:     ;
  
  labeledStatement
      :   'case' constantExpression ':' statement
      |   'default' ':' statement
      ;
  
  