Require a pointer + macro arg protection

include/grpc/support/useful.h

@@ -52,13 +52,13 @@
     b = x;               \
   } while (0)
 
-/** Set the \a n-th bit of \a i */
-#define GPR_BITSET(i, n) (i |= (1u << n))
+/** Set the \a n-th bit of \a i (a mutable pointer). */
+#define GPR_BITSET(i, n) ((*(i)) |= (1u << n))
 
-/** Clear the \a n-th bit of \a i */
-#define GPR_BITCLEAR(i, n) (i &= ~(1u << n))
+/** Clear the \a n-th bit of \a i (a mutable pointer). */
+#define GPR_BITCLEAR(i, n) ((*(i)) &= ~(1u << n))
 
 /** Get the \a n-th bit of \a i */
-#define GPR_BITGET(i, n) ((i & (1u << n)) != 0)
+#define GPR_BITGET(i, n) (((i) & (1u << n)) != 0)
 
 #endif  /* GRPC_SUPPORT_USEFUL_H */

test/core/support/useful_test.c

@@ -56,10 +56,10 @@ int main(int argc, char **argv) {
   GPR_ASSERT(GPR_ARRAY_SIZE(four) == 4);
   GPR_ASSERT(GPR_ARRAY_SIZE(five) == 5);
 
-  GPR_ASSERT(GPR_BITSET(bitset, 3) == 8);
+  GPR_ASSERT(GPR_BITSET(&bitset, 3) == 8);
   GPR_ASSERT(GPR_BITGET(bitset, 3) == 1);
-  GPR_ASSERT(GPR_BITSET(bitset, 1) == 10);
-  GPR_ASSERT(GPR_BITCLEAR(bitset, 3) == 2);
+  GPR_ASSERT(GPR_BITSET(&bitset, 1) == 10);
+  GPR_ASSERT(GPR_BITCLEAR(&bitset, 3) == 2);
   GPR_ASSERT(GPR_BITGET(bitset, 3) == 0);
 
   return 0;