src/test/ui/generator/issue-68112.rs

   1 #![feature(generators, generator_trait)]
   2
   3 use std::{
   4     cell::RefCell,
   5     sync::Arc,
   6     pin::Pin,
   7     ops::{Generator, GeneratorState},
   8 };
   9
  10 pub struct Ready<T>(Option<T>);
  11 impl<T> Generator<()> for Ready<T> {
  12     type Return = T;
  13     type Yield = ();
  14     fn resume(mut self: Pin<&mut Self>, _args: ()) -> GeneratorState<(), T> {
  15         GeneratorState::Complete(self.0.take().unwrap())
  16     }
  17 }
  18 pub fn make_gen1<T>(t: T) -> Ready<T> {
  19     Ready(Some(t))
  20 }
  21
  22 fn require_send(_: impl Send) {}
  23 //~^ NOTE required by a bound
  24 //~| NOTE required by a bound
  25 //~| NOTE required by this bound
  26 //~| NOTE required by this bound
  27
  28 fn make_non_send_generator() -> impl Generator<Return = Arc<RefCell<i32>>> {
  29     make_gen1(Arc::new(RefCell::new(0)))
  30 }
  31
  32 fn test1() {
  33     let send_gen = || {
  34         let _non_send_gen = make_non_send_generator();
  35         //~^ NOTE not `Send`
  36         yield;
  37         //~^ NOTE yield occurs here
  38         //~| NOTE value is used across a yield
  39     }; //~ NOTE later dropped here
  40     require_send(send_gen);
  41     //~^ ERROR generator cannot be sent between threads
  42     //~| NOTE not `Send`
  43 }
  44
  45 pub fn make_gen2<T>(t: T) -> impl Generator<Return = T> {
  46 //~^ NOTE appears within the type
  47 //~| NOTE expansion of desugaring
  48     || { //~ NOTE used within this generator
  49         yield;
  50         t
  51     }
  52 }
  53 fn make_non_send_generator2() -> impl Generator<Return = Arc<RefCell<i32>>> { //~ NOTE appears within the type
  54 //~^ NOTE expansion of desugaring
  55     make_gen2(Arc::new(RefCell::new(0)))
  56 }
  57
  58 fn test2() {
  59     let send_gen = || { //~ NOTE used within this generator
  60         let _non_send_gen = make_non_send_generator2();
  61         yield;
  62     };
  63     require_send(send_gen);
  64     //~^ ERROR `RefCell<i32>` cannot be shared between threads safely
  65     //~| NOTE `RefCell<i32>` cannot be shared between threads safely
  66     //~| NOTE required for
  67     //~| NOTE required by a bound introduced by this call
  68     //~| NOTE captures the following types
  69 }
  70
  71 fn main() {}