Add a bindings-only version of `Future::register_callback`

While we could, in theory, add support to the bindings logic to map
`Box<dyn Trait>`, there isn't a whole lot of use doing so when its
incredibly trivial to do directly.

This adds a trivial wrapper around `Future::register_callback` that
is only built in bindings and which is linked in the
`register_callback` docs for visibility.

diff --git a/lightning/src/util/wakers.rs b/lightning/src/util/wakers.rs
index e49c832ef67fd8aeb0dd25f193eb3fe179bb57c1..166771948fad62bc2f10078b5360fb67207f50f5 100644 (file)
--- a/lightning/src/util/wakers.rs
+++ b/lightning/src/util/wakers.rs
@@ -163,6 +163,8 @@ pub struct Future {
 impl Future {
        /// Registers a callback to be called upon completion of this future. If the future has already
        /// completed, the callback will be called immediately.
+       ///
+       /// (C-not exported) use the bindings-only `register_callback_fn` instead
        pub fn register_callback(&self, callback: Box<dyn FutureCallback>) {
                let mut state = self.state.lock().unwrap();
                if state.complete {
@@ -172,6 +174,16 @@ impl Future {
                        state.callbacks.push(callback);
                }
        }
+
+       // C bindings don't (currently) know how to map `Box<dyn Trait>`, and while it could add the
+       // following wrapper, doing it in the bindings is currently much more work than simply doing it
+       // here.
+       /// Registers a callback to be called upon completion of this future. If the future has already
+       /// completed, the callback will be called immediately.
+       #[cfg(c_bindings)]
+       pub fn register_callback_fn<F: 'static + FutureCallback>(&self, callback: F) {
+               self.register_callback(Box::new(callback));
+       }
 }
 
 mod std_future {