src/test/compile-fail/impl-trait/auto-trait-leak.rs

   1 // Copyright 2016 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // ignore-tidy-linelength
  12
  13 #![feature(conservative_impl_trait)]
  14
  15 use std::cell::Cell;
  16 use std::rc::Rc;
  17
  18 // Fast path, main can see the concrete type returned.
  19 fn before() -> impl Fn(i32) {
  20     let p = Rc::new(Cell::new(0));
  21     move |x| p.set(x)
  22 }
  23
  24 fn send<T: Send>(_: T) {}
  25
  26 fn main() {
  27     send(before());
  28     //~^ ERROR the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` is not satisfied
  29     //~| NOTE trait `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` not satisfied
  30     //~| NOTE `std::rc::Rc<std::cell::Cell<i32>>` cannot be sent between threads safely
  31     //~| NOTE required because it appears within the type `[closure
  32     //~| NOTE required because it appears within the type `impl std::ops::Fn<(i32,)>`
  33     //~| NOTE required by `send`
  34
  35     send(after());
  36     //~^ ERROR the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` is not satisfied
  37     //~| NOTE trait `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` not satisfied
  38     //~| NOTE `std::rc::Rc<std::cell::Cell<i32>>` cannot be sent between threads safely
  39     //~| NOTE required because it appears within the type `[closure
  40     //~| NOTE required because it appears within the type `impl std::ops::Fn<(i32,)>`
  41     //~| NOTE required by `send`
  42 }
  43
  44 // Deferred path, main has to wait until typeck finishes,
  45 // to check if the return type of after is Send.
  46 fn after() -> impl Fn(i32) {
  47     let p = Rc::new(Cell::new(0));
  48     move |x| p.set(x)
  49 }
  50
  51 // Cycles should work as the deferred obligations are
  52 // independently resolved and only require the concrete
  53 // return type, which can't depend on the obligation.
  54 fn cycle1() -> impl Clone {
  55     send(cycle2().clone());
  56     //~^ ERROR the trait bound `std::rc::Rc<std::string::String>: std::marker::Send` is not satisfied
  57     //~| NOTE trait `std::rc::Rc<std::string::String>: std::marker::Send` not satisfied
  58     //~| NOTE `std::rc::Rc<std::string::String>` cannot be sent between threads safely
  59     //~| NOTE required because it appears within the type `impl std::clone::Clone`
  60     //~| NOTE required by `send`
  61
  62     Rc::new(Cell::new(5))
  63 }
  64
  65 fn cycle2() -> impl Clone {
  66     send(cycle1().clone());
  67     //~^ ERROR the trait bound `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` is not satisfied
  68     //~| NOTE trait `std::rc::Rc<std::cell::Cell<i32>>: std::marker::Send` not satisfied
  69     //~| NOTE `std::rc::Rc<std::cell::Cell<i32>>` cannot be sent between threads safely
  70     //~| NOTE required because it appears within the type `impl std::clone::Clone`
  71     //~| NOTE required by `send`
  72
  73     Rc::new(String::from("foo"))
  74 }