proc_macro_attribute dependency

[exellian]

Let's assume you have two user defined proc_macro_attributes in the following order:

struct Test {}

#[depends_on_inner]
impl Test {

    #[inner]
    fn test() {

    }
}

Is there any way to hand over information between these two macro executions, so that depends_on_inner knows that impl Test has a function with a #[inner] attribute?

[ehuss]

I'm uncertain if there's a common way to relay information. depends_on_inner can parse its input and notice the presence of the inner attribute, but I'm uncertain if that's guaranteed (see #692 and its linked issues).

Questions like these should be asked on one of the user forums, like https://users.rust-lang.org/.

[exellian]

Ok thanks!

[Caellian]

For future reference if anyone stumbles upon this issue:

Instead of defining #[inner] as a separate macro, process it (assuming you're using syn) by detecting it from ImplItem::attributes and then passing it to the same processor fn you otherwise would. If you need #[inner] to work on its own you must name the version bound to #[depends_on_inner] differently as order of expansion is not guaranteed and might change depending on target/version.