Invalid macro expansion when async-trait and duplicate_item macros are used together

[Veetaha]

I think this is a regression. I don't know when it happened, but judging by the commit date of the code where I see this broken today, it was 5 months ago (May 26th, 2022). I wouldn't leave it like this if it didn't work at that time for sure.

Reproduction repository.

Screenshot

Code:

use async_trait::async_trait;
use duplicate::duplicate_item;

#[async_trait]
pub trait Foo {
    #[duplicate_item(
        var;
        [foo];
    )]
    async fn foo(&self);
}

pub fn foo(val: &dyn Foo) {


    let _ = val.foo();
}

Result of "Expand macro recursively":

// Recursive expansion of async_trait! macro
// ==========================================

pub trait Foo {
    compile_error! {
      "Unexpected token. Expected substitution identifier or ';' instead."
    }
}

Expected

The usage of duplicate_item here is actually noop. I.e. it just leaves the decorated trait method as is. Rust-analyzer should see this, and correctly resolve the trait method.

Actual

Rust-analyzer fails to expand the macro, so the trait method isn't seen in completions and isn't highlighted.

Meta

rust-analyzer version: 0.3.1258-standalone

rustc version: 1.64.0 (a55dd71d5 2022-09-19)

relevant settings:

This works both with async-trait macro enabled and disabled in the settings via:

"rust-analyzer.procMacro.ignored": {
    "async-trait": ["async_trait"]
}

I have it disabled in the settings during regular development