Crate caller_modpath

Getting the module path of the caller within a #[proc_macro_attribute].

This crate provides two items:

• #[expose_caller_modpath]
• CallerModpath::caller_modpath

The first makes the second available; see the documentation on each for more information.

Example

#[caller_modpath::expose_caller_modpath]
#[proc_macro_attribute]
pub fn test(_attr: TokenStream, _input: TokenStream) -> TokenStream {
    let modpath: String = proc_macro::Span::caller_modpath();
    // now do something with it. For example, just panic to have the compiler display the result:
    panic!(
        "module path of call site: {}",
        modpath
    );
}

Nightly Requirement

This crate internally uses the proc_macro_span feature. This is only used to test the equality of two Spans. If you know how to do this without nightly, file an issue or PR on the upstream GitHub repo. Help is greatly appreciated!

Backend

This crate causes the macro invoker to call rustc on itself. #[expose_caller_modpath] performans some setup such that on the meta-call the target macro essentially expands to module_path!() with some additional identifiers. These identifiers are read within CallerModpath::caller_modpath, which does the rustc meta-call, parsing and returning the value.

Because this crate does some terribly non-standard stuff, issues are bound to occur. If you run into something, file an issue at the upstream GitHub repo.

Traits

CallerModpath

Provides a way to fetch the module path of the caller.

Attribute Macros

expose_caller_modpath

Makes Span::caller_modpath() available to the applied macro, and all functions which it calls.