| //@ edition:2018 |
| #![allow(dead_code)] |
| use std::future::Future; |
| use std::pin::Pin; |
| |
| type BoxFuture<'a, T> = Pin<Box<dyn Future<Output = T> + Send + 'a>>; |
| // ^^^^^^^^^ This would come from the `futures` crate in real code. |
| |
| fn foo<F: Future<Output=i32> + Send + 'static>(x: F) -> BoxFuture<'static, i32> { |
| // We could instead use an `async` block, but this way we have no std spans. |
| x //~ ERROR mismatched types |
| } |
| |
| fn bar<F: Future<Output=i32> + Send + 'static>(x: F) -> BoxFuture<'static, i32> { |
| Box::new(x) //~ ERROR mismatched types |
| } |
| |
| fn baz<F: Future<Output=i32> + Send + 'static>(x: F) -> BoxFuture<'static, i32> { |
| Pin::new(x) //~ ERROR mismatched types |
| //~^ ERROR E0277 |
| } |
| |
| fn qux<F: Future<Output=i32> + Send + 'static>(x: F) -> BoxFuture<'static, i32> { |
| Pin::new(Box::new(x)) //~ ERROR E0277 |
| } |
| |
| fn zap() -> BoxFuture<'static, i32> { |
| async { //~ ERROR mismatched types |
| 42 |
| } |
| } |
| |
| fn main() {} |