Wrong report for index out of bounds

[huanghaifeng]

Below is a simple code:

#define M 2

struct Key {
  int sts;
};
typedef struct Key keytype;

typedef struct page {
  keytype key[2 * M];
} *pageptr;

pageptr NewPage();

void BkSplit(pageptr p, int k) {
  int j, m;
  pageptr q;

  if (k <= M) {
    m = M;
  } else {
    m = M + 1;
  }

  q = Newpage();
   for (j = m + 1; j <= 2 * M; j++) {
     q->key[j-m-1] = p->key[j-1];
   }
}

When I run cppcheck, It outputs below error:

[C:/Users/xxxx/Desktop/cppcheck.c:27] (error) Array 'q->key[4]' accessed at index -1, which is out of bounds. [negativeIndex]

I can sure there is no 'index out of bounds.

How to solve this problem?

[CHR]

Thanks for reporting this false positive. Ticket is here: https://trac.cppcheck.net/ticket/11844