Implement AsFilename for `AsRef<OsStr>`

[WardBrian]

This is generated by Bindgen when wrapping a dynamic library, e.g. https://github.com/rust-lang/rust-bindgen/blob/6fe53022c2506b93fa15e097d3016bb29948cbee/bindgen-tests/tests/expectations/tests/dynamic_loading_simple.rs#L21-L25

[nagisa]

Thank you for the report. This is unfortunately not trivial to do as it conflicts with pretty much any other implementation. There are a couple options here we can consider:

1. Have just AsFilename for AsRef<OsStr> for cfg(feature = "std") and the usual implementations for cfg(not(feature = "std"));
   • This effectively prevents any future evolution of AsFilename, though.
2. Update rust-bindgen to support 0.9. This is relatively easy. I made a PR for this at feat(dyngen): preconvert path to OsStr when opening the library rust-lang/rust-bindgen#3315

[WardBrian]

Thanks!

I wasn't sure if it would be better to open the issue here or against bindgen, but the changelog note file an issue if you rely on a type that no longer works. made me pick here -- ultimately, either fix makes me happy as a downstream user :)

[nagisa]

Since we've addressed the specific problem with rust-bindgen downstream I'm going to close this out as I don't think anything else needs to be done for that particular use-case. But I still welcome reports for other issues related to these traits so we can look at them.