Closed
Description
rustexplorer (rustexplorer is a playground alternative, I'm using it because play.rust-lang.org doesn't exposes tracing attributes)
This is probably related to some other issues, like #71968, but I decided to open it either way because the diagnostics differ from the async and sync version.
Simplifying my real case, given some struct:
#[derive(Debug)]
struct Foo;I've tried implementing some instrumented associated async fn and hit check before finishing the code:
impl Foo {
#[tracing::instrument()]
async fn missing_implementation(&self) -> char {}
#[tracing::instrument()]
async fn missing_wrapper(&self) -> Option<char> {
'a'
}
}which gave me weird diagnostics, especially the last one:
--> src/main.rs:10:5
|
10 | #[tracing::instrument()]
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected `char`, found `()`
error[E0308]: mismatched types
--> src/main.rs:13:5
|
13 | #[tracing::instrument()]
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected enum `Option`, found `char`
|
= note: expected enum `Option<char>`
found type `char`
help: try wrapping the expression in `Some`
|
13 | Some(#[tracing::instrument()])
| +++++ +but, to my surprise, testing with the sync version:
impl Foo {
#[tracing::instrument()]
fn missing_implementation(&self) -> char {}
#[tracing::instrument()]
fn missing_wrapper(&self) -> Option<char> {
'a'
}
}outputs:
error[E0308]: mismatched types
--> src/main.rs:19:51
|
19 | fn missing_implementation(&self) -> char {}
| ^^ expected `char`, found `()`
error[E0308]: mismatched types
--> src/main.rs:23:9
|
22 | fn missing_wrapper(&self) -> Option<char> {
| ------------ expected `Option<char>` because of return type
23 | 'a'
| ^^^ expected enum `Option`, found `char`
|
= note: expected enum `Option<char>`
found type `char`
help: try wrapping the expression in `Some`
|
23 | Some('a')
| +++++ +I expect the async version outputs the same diagnostics as the sync version.