I'm working on a dependency injection / dependency inversion framework for Rust (GitHub - Leandros/ferrunix: A simple, idiomatic, and lightweight dependency injection framework for Rust.). I'm in the process of adding fallible constructors (returning Result<T>, instead of T) and adding support for async closures (so users won't have to use bare boxed futures anymore, no more Box::pin(async move { ... })).
Unfortunately, async closures don't support restricting the bounds of the future in stable Rust (in nightly this can be enabled); therefore, a workaround is required.
This workaround, generally, works, however, it seems to break type inference in rustc (interestingly, rust analyzer can correctly infer the types).
I've created a small example, which, unfortunately, is still almost 300 lines long. The two interesting parts are the workaround AsyncCtor and AsyncCtorLifetime, and the invocation in main.
Has anyone got any idea how I could convince rustc to properly infer the types? If the workaround is removed, inference works, but the actual implementation on line 92 and 93 needs to be replaced by a todo! to see it in action.