Two weeks ago, I came across an interesting bug. The convert() function below returns 0x80000001 when p points to 0x01, 0x00, 0x00, 0x80, but the expected return value is 0x00000001 instead.

int32_t convert(const uint8_t *restrict p) {
  uint32_t x = (                  p[0] +
                256 *             p[1] +
                256 * 256 *       p …