neatogen cmpitem: rephrase comparator to avoid arithmetic

cccb8b1d22a18031fc92d93133c7fa14ef7e1361 fixed an integer overflow in a
`memcmp`-/`strcmp`-like comparator. The same situation exists in the code
touched in this commit. Rather than wait for an edge case to expose an overflow
here, this change makes the same update, removing arithmetic and the consequent
possibility of overflow.

diff --git a/lib/neatogen/constraint.c b/lib/neatogen/constraint.c
index a6ad8caa162d83d30cbfe4af3009698ed163522c..1cc689774298d9ffea009db4dcd3aea0f84f77f4 100644 (file)
--- a/lib/neatogen/constraint.c
+++ b/lib/neatogen/constraint.c
@@ -38,7 +38,13 @@ static int cmpitem(Dt_t * d, int *p1, int *p2, Dtdisc_t * disc)
     (void)d;
     (void)disc;
 
-    return (*p1 - *p2);
+    if (*p1 < *p2) {
+        return -1;
+    }
+    if (*p1 > *p2) {
+        return 1;
+    }
+    return 0;
 }
 
 static Dtdisc_t constr = {