src/test/ui/lang-items/lang-item-missing-generator.rs

   1 // error-pattern: requires `generator` lang_item
   2 #![feature(no_core, lang_items, unboxed_closures, tuple_trait)]
   3 #![no_core]
   4
   5 #[lang = "sized"] pub trait Sized { }
   6
   7 #[lang = "tuple_trait"] pub trait Tuple { }
   8
   9 #[lang = "fn_once"]
  10 #[rustc_paren_sugar]
  11 pub trait FnOnce<Args: Tuple> {
  12     type Output;
  13
  14     extern "rust-call" fn call_once(self, args: Args) -> Self::Output;
  15 }
  16
  17 pub fn abc() -> impl FnOnce(f32) {
  18     |_| {}
  19 }
  20
  21 fn main() {}