Header generation control for Rust workspace monorepo

[kriswuollett]

Say I have three packages my-error-codes, my-logging, and my-runtime. The latter packages both depend on my-error-codes and use one of its enum in return values for ffi_export functions. When I generate headers for either my-logging or my-runtime the generated header includes things like enum types from my-error-codes as well as base types like slice_ref_uint8.

I'd like to:

• generate the base safer_ffi types into a header of my choosing, say /external/safer_ffi/safer_ffi.h
• instruct the header generation to know external types should be found in certain header file paths, sort of like how one would do prost types:

    for t in vec!["Any", "Duration"] {
        builder = builder.extern_path(
            format!(".google.protobuf.{t}"),
            format!("::prost_types::{t}"),
        );
    }

• so I could then in C application code import types from appropriate header paths rather than a single one.

Is this possible to implement, both from safer_ffi new feature perspective, as well as from the Rust build perspective that would let me mix and match libraries with ffi_exports to form a final static lib?

Is my only choice at this moment just creating that final static lib package and copy and pasting ffi_export function "wrappers" for the dependencies' pure-Rust functions to get everything I want, except in a single header file?