Unresolved import for a re-exported macro

[hulloitskai]

Hi, rust-analyzer appears to be giving me unresolved import when importing tokio::main:

use anyhow::Result;
use tokio::main as wrapper; // unresolved import

#[wrapper]
async fn main() → Result<()> {
  // ...
}

I do know that directly using #[tokio::main] instead of use-aliasing it will avoid the complaints from rust-analyzer; however, I believe this error points to a deeper issue with specific imports that should be addressed.

However, the code compiles properly. Upon closer inspection of the source containing the tokio::main macro, I see that it is embedded with several layers of macros to handle cfg (to only export the macro when certain tokio features are enabled):

cfg_macros! {
    /// Implementation detail of the `select!` macro. This macro is **not**
    /// intended to be used as part of the public API and is permitted to
    /// change.
    #[doc(hidden)]
    pub use tokio_macros::select_priv_declare_output_enum;

    cfg_rt! {
        cfg_rt_multi_thread! {
            // This is the docs.rs case (with all features) so make sure macros
            // is included in doc(cfg).

            #[cfg(not(test))] // Work around for rust-lang/rust#62127
            #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
            pub use tokio_macros::main;

            #[cfg_attr(docsrs, doc(cfg(feature = "macros")))]
            pub use tokio_macros::test;
        }

        cfg_not_rt_multi_thread! {
            #[cfg(not(test))] // Work around for rust-lang/rust#62127
            pub use tokio_macros::main_rt as main;
            pub use tokio_macros::test_rt as test;
        }
    }

    // Always fail if rt is not enabled.
    cfg_not_rt! {
        #[cfg(not(test))]
        pub use tokio_macros::main_fail as main;
        pub use tokio_macros::test_fail as test;
    }
}

Perhaps it is the expansion of these macros, or the #[cfg(not(test))], that is tripping up rust-analyzer?

[ArifRoktim]

Does adding

    "rust-analyzer.procMacro.enable": true,
    "rust-analyzer.cargo.loadOutDirsFromCheck": true,

to your configuration fix the issue? Proc Macro support is disabled by default.

[hulloitskai]

I already had those options enabled when I reported this issue. But good call, should have included that info in the report!

…

On Nov 7, 2020, 4:07 PM -0500, Arif Roktim ***@***.***>, wrote: Does adding "rust-analyzer.procMacro.enable": true, "rust-analyzer.cargo.loadOutDirsFromCheck": true, to your configuration fix the issue? Proc Macro support is disabled by default. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[jonas-schievink]

Perhaps it is the expansion of these macros, or the #[cfg(not(test))], that is tripping up rust-analyzer?

It is the #[cfg(not(test))]. rust-analyzer always enables the test cfg.

However it seems that the Rust issue this is working around, rust-lang/rust#62127, has been fixed, so the workaround in tokio can probably be removed now.

[jonas-schievink]

Ah nevermind it was closed as wontfix.

[Veykril]

This can be worked around by adding tokio-macros to the rust-analyzer.cargo.unsetTest setting now.