Work around for using proc-macro libs

[Christian-Prather]

Hello,
I am currently evaluating using Corrosion to simplify some existing cmake magic in a project. The general structure is that there is a top level cmake and Cargo.toml file which defines a workspace of packages. One of these packages is a macro library which leverages proc-macro.

Unfortunately since Corrosion only supports staticlib, cdylib, and dylib AND because proc-macro libs cannot be built in combination with any of those I am unable to use Corrosion to build this package.

I am at a bit of a loss of how to go about this as I would love to get this working and this package is a core dependency for many of my other crates.

Any advice would be greatly appreciated!

[jschwe]

Could you elaborate on your problem? proc macro crates will be built perfectly fine as dependencies, since Corrosion invokes cargo build.
Is there any reason you need to expose the proc macro lib as a CMake target?

[Christian-Prather]

Thanks for the reply,

We currently have a package callled custom_macros with a toml file that looks something like this

[package]
name = "custom_macros"

[lib]
proc-macro = true

[dependencies]
syn = "2.0"
quote = "1.0"
proc-macro2 = "1.0"
darling = "0.20.1"
itertools = "0.11"

This crate is then itself a dependency for others in our workspace that I am trying to build with Corrosion.

[dependencies]
async-trait = "0.1.68"
custom_macros = "*"

If there is something inherently wrong with this I am open to how it should be done. Thank you in advance!

[Christian-Prather]

I actually think I may have just been misunderstanding my errors. I believe the core issue is actually that Corrosion doesnt seem to be correctly picking up clippy allows and thus the proc-macros lib is panicking at compile time. I currently have this line in my custom_macros lib.rs #![allow(clippy::expect_used, clippy::unwrap_used, clippy::panic)] which was needed prior to my use of Corrosion but when I build with Corrosion I get errors around macros not used.

error: fields `fields` are never read
   |
23 | pub struct Variant {
   |            ------- fields in this struct
...
39 |     pub fields: proc_macro2::TokenStream,
   |         ^^^^^^

[jschwe]

Your error doesn't look like a clippy error and instead more like something that needs
#[allow(dead_code)] or similar.

[Christian-Prather]

Yes that was it thank you!