--- /dev/null
+// check-pass
+
+#![allow(unreachable_code, unused)]
+
+use std::marker::PhantomData;
+
+struct FsmBuilder<TFsm> {
+ _fsm: PhantomData<TFsm>,
+}
+
+impl<TFsm> FsmBuilder<TFsm> {
+ fn state(&mut self) -> FsmStateBuilder<TFsm> {
+ todo!()
+ }
+}
+
+struct FsmStateBuilder<TFsm> {
+ _state: PhantomData<TFsm>,
+}
+
+impl<TFsm> FsmStateBuilder<TFsm> {
+ fn on_entry<TAction: Fn(&mut StateContext<'_, TFsm>)>(&self, _action: TAction) {}
+}
+
+trait Fsm {
+ type Context;
+}
+
+struct StateContext<'a, TFsm: Fsm> {
+ context: &'a mut TFsm::Context,
+}
+
+fn main() {
+ let mut builder: FsmBuilder<usize> = todo!();
+ builder.state().on_entry(|_| {});
+}