1 #define MASK ((1 << __CHAR_BIT__) - 1)
   2 
   3 void foo(void)
   4 {
   5         _Static_assert((char) -1 == (-1 & MASK), "plain char is not unsigned");
   6 }
   7 
   8 /*
   9  * check-name: fsigned-char
  10  * check-command: sparse -funsigned-char -Wno-decl $file
  11  */