`Pin<_>` errors on tokio::try_join

[Pauline]

Version

│   ├── tokio v1.36.0
│   │   └── tokio-macros v2.2.0 (proc-macro)
│   ├── tokio-native-tls v0.3.1
│   │   └── tokio v1.36.0 (*)
│   │   │   ├── tokio v1.36.0 (*)
│   │   │   ├── tokio-util v0.7.10
│   │   │   │   ├── tokio v1.36.0 (*)
│   │   │   ├── tokio v1.36.0 (*)
│   │   │   │   ├── tokio v1.36.0 (*)
│   │   │   │   │   ├── tokio v1.36.0 (*)
│   │   │   ├── tokio v1.36.0 (*)
│   │   │   ├── tokio-native-tls v0.3.1 (*)
│   │   ├── tokio v1.36.0 (*)
│   │   ├── tokio-native-tls v0.3.1 (*)
│   │   ├── tokio-util v0.7.10 (*)
│   └── tokio v1.36.0 (*)
│   │   │   ├── tokio v1.36.0 (*)
│   │   │   ├── tokio-util v0.7.10 (*)
│   │   │   ├── tokio v1.36.0 (*)
│   │   ├── tokio v1.36.0 (*)
│   │   ├── tokio-util v0.7.10 (*)
│   ├── tokio v1.36.0 (*)
├── tokio v1.36.0 (*)
├── tokio-stream v0.1.15
│   └── tokio v1.36.0 (*)
├── tokio v1.36.0 (*)
└── tokio v1.36.0 (*)

Platform
MacOS Sonoma 14.4.1

Description
I am trying to make a wrapper over tokio::try_join! , which accepts multiple async outputs that are awaited on with custom logic and then added to the try_join! block.

I tried this code:

#[macro_export]
macro_rules! tokio_test {
    () => {
        {
            paste::paste! {
                tokio::try_join! (
                    $( [ <name $task>] ),+
                )
            }
        }
    }
 }

I expected to see this happen: All async tasks would be added and run in the try_join! block with no errors.

Instead, this happened: I recieved two errors, one type annotations needed at try_join.rs:(174, 93), and another no method named take_outputfound for structPin<>in the current scope method not found inPin<>`` error at try_join.rs(196, 26).

[Alice Ryhl]

Your current example doesn't invoke the macro, so it does not trigger the error. Please provide a more complete reproducer.

[Alice Ryhl]

I tried using what you gave me, but it fails with unrelated errors:

   Compiling playground v0.0.1 (/playground)
error: expected expression, found `$`
  --> src/main.rs:7:29
   |
7  |               let increment = $total / num_futures as f64;
   |                               ^^^^^^ expected expression
...
34 |           let (clusters, users) = tokio_test! {
   |  _________________________________-
35 | |               Some("loading core features");
36 | |               clusters_in,
37 | |               users_in,
38 | |         }?;
   | |_________- in this macro invocation
   |
   = note: this error originates in the macro `tokio_test` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: could not find `count` in the crate root
  --> src/main.rs:6:39
   |
6  |               let num_futures = $crate::count!($($task)*);
   |                                         ^^^^^ could not find `count` in the crate root
...
34 |           let (clusters, users) = tokio_test! {
   |  _________________________________-
35 | |               Some("loading core features");
36 | |               clusters_in,
37 | |               users_in,
38 | |         }?;
   | |_________- in this macro invocation
   |
   = note: this error originates in the macro `tokio_test` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0308]: mismatched types
  --> src/main.rs:33:5
   |
32 |   async fn main() {
   |                  - expected `()` because of default return type
33 | /     Box::pin(async move {
34 | |         let (clusters, users) = tokio_test! {
35 | |               Some("loading core features");
36 | |               clusters_in,
37 | |               users_in,
38 | |         }?;
39 | |     })
   | |______^ expected `()`, found `Pin<Box<...>>`
   |
   = note: expected unit type `()`
                 found struct `Pin<Box<{async block@src/main.rs:33:14: 39:6}>>`

Some errors have detailed explanations: E0308, E0433.
For more information about an error, try `rustc --explain E0308`.
error: could not compile `playground` (bin "playground") due to 3 previous errors

Click here for playground

I can't tell what the problem is from just looking at your code, so I really need a complete example that I can run myself. Without code that I can run and tweak myself, I can't help you.