480c4a18d5
Remove confusing 'while checking' note from opaque future type mismatches
Maybe I'm just misinterpreting the wording of the note. The only value I can see in this note is that it points out where the async's opaque future is coming from, but the way it's doing it is misleading IMO.
For example:
```rust
note: while checking the return type of the `async fn`
--> $DIR/dont-suggest-missing-await.rs:7:24
|
LL | async fn make_u32() -> u32 {
| ^^^ checked the `Output` of this `async fn`, found opaque type
```
We point at the type `u32` in the HIR, but then say "found opaque type". We also say "while checking"... but we're typechecking a totally different function when we get this type mismatch!
r? ``@estebank`` but feel free to reassign and/or take your time reviewing this. I'd be inclined to also discuss reworking the presentation of this type mismatch to restore some of these labels in a way that makes it more clear what it's trying to point out.
95 lines
2.6 KiB
Rust
95 lines
2.6 KiB
Rust
// edition:2018
|
|
|
|
use core::future::Future;
|
|
use core::pin::Pin;
|
|
use core::task::{Context, Poll};
|
|
|
|
struct T;
|
|
|
|
struct Tuple(i32);
|
|
|
|
struct Struct {
|
|
a: i32
|
|
}
|
|
|
|
impl Struct {
|
|
fn method(&self) {}
|
|
}
|
|
|
|
impl Future for Struct {
|
|
type Output = Struct;
|
|
fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> { Poll::Pending }
|
|
}
|
|
|
|
impl Future for Tuple {
|
|
type Output = Tuple;
|
|
fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> { Poll::Pending }
|
|
}
|
|
|
|
impl Future for T {
|
|
type Output = Result<(), ()>;
|
|
|
|
fn poll(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Self::Output> {
|
|
Poll::Pending
|
|
}
|
|
}
|
|
|
|
async fn foo() -> Result<(), ()> {
|
|
Ok(())
|
|
}
|
|
|
|
async fn bar() -> Result<(), ()> {
|
|
foo()?; //~ ERROR the `?` operator can only be applied to values that implement `Try`
|
|
//~^ NOTE the `?` operator cannot be applied to type `impl Future<Output = Result<(), ()>>`
|
|
//~| HELP the trait `Try` is not implemented for `impl Future<Output = Result<(), ()>>`
|
|
//~| HELP consider `await`ing on the `Future`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
Ok(())
|
|
}
|
|
|
|
async fn struct_() -> Struct {
|
|
Struct { a: 1 }
|
|
}
|
|
|
|
async fn tuple() -> Tuple {
|
|
Tuple(1i32)
|
|
}
|
|
|
|
async fn baz() -> Result<(), ()> {
|
|
let t = T;
|
|
t?; //~ ERROR the `?` operator can only be applied to values that implement `Try`
|
|
//~^ NOTE the `?` operator cannot be applied to type `T`
|
|
//~| HELP the trait `Try` is not implemented for `T`
|
|
//~| HELP consider `await`ing on the `Future`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
//~| NOTE in this expansion of desugaring of operator `?`
|
|
|
|
|
|
let _: i32 = tuple().0; //~ ERROR no field `0`
|
|
//~^ HELP consider `await`ing on the `Future`
|
|
//~| NOTE field not available in `impl Future`
|
|
|
|
let _: i32 = struct_().a; //~ ERROR no field `a`
|
|
//~^ HELP consider `await`ing on the `Future`
|
|
//~| NOTE field not available in `impl Future`
|
|
|
|
struct_().method(); //~ ERROR no method named
|
|
//~^ NOTE method not found in `impl Future<Output = Struct>`
|
|
//~| HELP consider `await`ing on the `Future`
|
|
Ok(())
|
|
}
|
|
|
|
async fn match_() {
|
|
match tuple() { //~ HELP consider `await`ing on the `Future`
|
|
//~^ NOTE this expression has type `impl Future<Output = Tuple>`
|
|
Tuple(_) => {} //~ ERROR mismatched types
|
|
//~^ NOTE expected opaque type, found `Tuple`
|
|
//~| NOTE expected opaque type `impl Future<Output = Tuple>`
|
|
}
|
|
}
|
|
|
|
fn main() {}
|