// check-pass // pretty-expanded FIXME #23616 #![feature(fn_traits, unboxed_closures)] use std::ops::Fn; trait Response { fn dummy(&self) { } } trait Request { fn dummy(&self) { } } trait Ingot<R, S> { fn enter(&mut self, _: &mut R, _: &mut S, a: &mut Alloy) -> Status; } #[allow(dead_code)] struct HelloWorld; struct SendFile; struct Alloy; enum Status { Continue } impl Alloy { fn find<T>(&self) -> Option<T> { None } } impl<'b> Fn<(&'b mut (dyn Response + 'b),)> for SendFile { extern "rust-call" fn call(&self, (_res,): (&'b mut (dyn Response + 'b),)) {} } impl<'b> FnMut<(&'b mut (dyn Response + 'b),)> for SendFile { extern "rust-call" fn call_mut(&mut self, (_res,): (&'b mut (dyn Response+'b),)) { self.call((_res,)) } } impl<'b> FnOnce<(&'b mut (dyn Response + 'b),)> for SendFile { type Output = (); extern "rust-call" fn call_once(self, (_res,): (&'b mut (dyn Response+'b),)) { self.call((_res,)) } } impl<Rq: Request, Rs: Response> Ingot<Rq, Rs> for HelloWorld { fn enter(&mut self, _req: &mut Rq, res: &mut Rs, alloy: &mut Alloy) -> Status { let send_file = alloy.find::<SendFile>().unwrap(); send_file(res); Status::Continue } } fn main() {}