diff options
| -rw-r--r-- | futures/src/subscription.rs | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/futures/src/subscription.rs b/futures/src/subscription.rs index 4d5a1192..1ee291c1 100644 --- a/futures/src/subscription.rs +++ b/futures/src/subscription.rs @@ -89,14 +89,22 @@ impl<Message> Subscription<Message> { } /// Transforms the [`Subscription`] output with the given function. - pub fn map<A>( - mut self, - f: impl Fn(Message) -> A + MaybeSend + Clone + 'static, - ) -> Subscription<A> + /// + /// # Panics + /// The closure provided must be a non-capturing closure. The method + /// will panic in debug mode otherwise. + pub fn map<F, A>(mut self, f: F) -> Subscription<A> where Message: 'static, + F: Fn(Message) -> A + MaybeSend + Clone + 'static, A: 'static, { + debug_assert!( + std::mem::size_of::<F>() == 0, + "the closure {} provided in `Subscription::map` is capturing", + std::any::type_name::<F>(), + ); + Subscription { recipes: self .recipes |