Generators are not supported by TokenStream

[QuentinPerez]

I tried this code:

#[proc_macro_attribute]
pub fn test_generatror(
    _: proc_macro::TokenStream,
    _: proc_macro::TokenStream,
) -> proc_macro::TokenStream {
    quote! {
        pub async gen fn my_gen_fn() -> u32 {
            0
        }
    }
    .into()
}

I expected to see this happen: No error

Instead, this happened: I got this error

#[test_generatror]
   | ^^^^^^^^^^^^ the visibility
   |
   = help: you likely meant to define an item, e.g., `pub fn foo() {}`
   = note: this error originates in the attribute macro `test_generatror` (in Nightly builds, run with -Z macro-backtrace for more info)

If bandwidth is limited, I'm willing to attempt integration. Could you please provide some guidance on how to proceed?

Meta

rustc --version --verbose:

rustc 1.79.0-nightly (1388d7a06 2024-03-20)
binary: rustc
commit-hash: 1388d7a069d872bcfe5e5dd97ef61fa0a586fac0
commit-date: 2024-03-20
host: aarch64-apple-darwin
release: 1.79.0-nightly
LLVM version: 18.1.2

[Nilstrieb]

That's not quite the entire error, could you post that, including a full reproduction? I don't think there is anything about proc macros that is wrong here... are you using syn?

[taiki-e]

pub async gen fn is not supported in the first place, right? The error can be reproduced without TokenStream: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=9680400c367f31fd92047c1b422bee9a

[fmease]

You need to use Rust 2024.

[taiki-e]

Ah, I missed that. In that case, I guess the problem may be that the crate that defines macro is a pre-2024 edition since call_site span inherits its edition and the error message seems to be the same as the one that occurs when using it in older editions. (Although, I do not know what the edition actually is, as a complete reproduction is not provided.)

[QuentinPerez]

You need to use Rust 2024.

You right, I forgot to add it in the proc macro lib. Thank you !