Use proper cfg

src/build/app/mod.rs

@@ -1435,13 +1435,12 @@ impl<'b> App<'b> {
 
         self._derive_display_order();
         self._create_help_and_version();
+
         // Perform expensive debug assertions
-        debug_assert!({
+        #[cfg(debug_assertions)]
         for a in self.args.args.iter() {
             self._arg_debug_asserts(a);
         }
-            true
-        });
 
         let mut pos_counter = 1;
         for a in self.args.args.iter_mut() {