MDEV-20377: Fix -Wunused-but-set-variable

storage/innobase/data/data0data.cc

@@ -194,29 +194,20 @@ dtuple_validate(
 /*============*/
 	const dtuple_t*	tuple)	/*!< in: tuple */
 {
-	const dfield_t*	field;
-	ulint		n_fields;
-	ulint		len;
-	ulint		i;
-
 	ut_ad(tuple->magic_n == DATA_TUPLE_MAGIC_N);
+#ifdef HAVE_valgrind_or_MSAN
+	const ulint n_fields = dtuple_get_n_fields(tuple);
 
-	n_fields = dtuple_get_n_fields(tuple);
-
-	/* We dereference all the data of each field to test
-	for memory traps */
-
-	for (i = 0; i < n_fields; i++) {
-
-		field = dtuple_get_nth_field(tuple, i);
-		len = dfield_get_len(field);
+	for (ulint i = 0; i < n_fields; i++) {
+		const dfield_t*	field = dtuple_get_nth_field(tuple, i);
 
 		if (!dfield_is_null(field)) {
-			MEM_CHECK_DEFINED(dfield_get_data(field), len);
+			MEM_CHECK_DEFINED(dfield_get_data(field),
+					  dfield_get_len(field));
 		}
 	}
-
-	ut_a(dtuple_check_typed(tuple));
+#endif /* HAVE_valgrind_or_MSAN */
+	ut_ad(dtuple_check_typed(tuple));
 
 	return(TRUE);
 }