text: #define	MASK ((1 << __CHAR_BIT__) - 1)
  
  void foo(void)
  {
  	_Static_assert((char) -1 == (-1 & MASK), "plain char is not unsigned");
  }
  
  /*
   * check-name: funsigned-char
   * check-command: sparse -funsigned-char -Wno-decl $file
   */
  