$ cat q.c
#include <stdio.h>
int main()
{
  int x[24]; int y=0; int z=x[--y];
  printf("y: %d", z);
  return 0;
}
$ gcc q.c -Wall -Wextra -Wuninitialized
q.c: In function ‘main’:
q.c:4:27: warning: ‘x[y]’ is used uninitialized in this function [-Wuninitialized]
    4 |   int x[24]; int y=0; int z=x[--y];
      |
$ cppcheck q.c  --enable=all
Checking q.c ...
q.c:4:30: error: Array 'x[24]' accessed at index -1, which is out of bounds. [negativeIndex]
  int x[24]; int y=0; int z=x[--y];
                             ^
q.c:4:20: note: Assignment 'y=0', assigned value is 0
  int x[24]; int y=0; int z=x[--y];
                   ^
q.c:4:30: note: Negative array index
  int x[24]; int y=0; int z=x[--y];
                             ^
q.c:4:7: style: Variable 'x' is not assigned a value. [unassignedVariable]
  int x[24]; int y=0; int z=x[--y];
      ^
nofile:0:0: information: Cppcheck cannot find all the include files (use --check-config for details) [missingIncludeSystem]