The interop is already great via PyO3, except when people want to build the Rust part from source, but are grumpy about having to install the Rust compiler.
This hack is a Rust compiler back-end. Backends get platform-specific instructions as an input, so non-trivial generated C code won't be portable. Users will need to either get pre-generated platform-specific source, or install the Rust compiler and this back-end to generate one themselves.
They are grumpy about having to install the Rust compiler for a good reason. You can’t compile for Rust on Windows without using MSVC via Visual Studio Build Tools, which has a restrictive license.
> When targeting the MSVC ABI, Rust additionally requires an installation of Visual Studio so rustc can use its linker and libraries.
> When targeting the GNU ABI, no additional software is strictly required for basic use. However, many library crates will not be able to compile until the full MSYS2 with MinGW has been installed.
...
> Since the MSVC ABI provides the best interoperation with other Windows software it is recommended for most purposes. The GNU toolchain is always available, even if you don’t use it by default.
This hack is a Rust compiler back-end. Backends get platform-specific instructions as an input, so non-trivial generated C code won't be portable. Users will need to either get pre-generated platform-specific source, or install the Rust compiler and this back-end to generate one themselves.