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 */ 12