src/test/ui/unboxed-closures/issue-30906.rs

   1 #![feature(fn_traits, unboxed_closures)]
   2
   3 // revisions: base nll
   4 // ignore-compare-mode-nll
   5 //[nll] compile-flags: -Z borrowck=mir
   6
   7 fn test<F: for<'x> FnOnce<(&'x str,)>>(_: F) {}
   8
   9 struct Compose<F, G>(F, G);
  10 impl<T, F, G> FnOnce<(T,)> for Compose<F, G>
  11 where
  12     F: FnOnce<(T,)>,
  13     G: FnOnce<(F::Output,)>,
  14 {
  15     type Output = G::Output;
  16     extern "rust-call" fn call_once(self, (x,): (T,)) -> G::Output {
  17         (self.1)((self.0)(x))
  18     }
  19 }
  20
  21 fn bad<T>(f: fn(&'static str) -> T) {
  22     test(Compose(f, |_| {}));
  23     //~^ ERROR: implementation of `FnOnce` is not general enough
  24 }
  25
  26 fn main() {}