Is it possible to have one crate with both procedural macros and logic?

Question

When you want to share a library that uses a procedural macro, is the dual crate approach foo/foo_derive inevitable?

I would like to provide a crate that has the logic and the macros. The first thing I tried was:

my_proc_macro
├── Cargo.toml
├── src/lib.rs
└── my_crate
    ├── Cargo.toml
    └── src/lib.rs

In the my_proc_macro crate, I tried to pub use my_crate::*; but it is forbidden to do so: the compiler refused to build this.

Is it possible to do this the other way around? I mean: import the procedural macro crate into the library and then reexport the macro?

I'm quite sure it can be done the other way around, but I'm not sure how. Look for example at [`rental`](https://crates.io/crates/rental), it has `rental-impl` as a dependency, but the user code does not have to write `extern crate rental_impl` so the `rental!` macro must be reexported by the main crate. — rodrigo, Oct 22 '18 at 14:12
@rodrigo Unfortunately, I do not think that's what `rental` does: it exports [a "regular" macro](https://github.com/jpernst/rental/blob/master/src/lib.rs#L220) that does the derive — Boiethios, Oct 22 '18 at 14:31

score 6 · Accepted Answer · answered Oct 22 '18 at 15:26

It's actually quite straight-forward to re-export macros. Simply use

#[macro_use]
extern crate my_proc_macro;

in the root of my_crate.

1 Answers1