Use Error trait in API

[epage]

cargo-release and cargo-smart-release are interested in integrating this into their process (see crate-ci/cargo-release#62). anyhow works well for bins but doesn't integrate well with libs which would be the ideal way to integrate so we don't have to worry about what other software end-users have installed.

[o0Ignition0o]

Hey there, thanks for hopping in!

It is very true, while we first thought of cargo-breaking as a cli tool, it would actually make sense for us to eventually expose a nice library and API, probably using thiserror instead of anyhow!

I think we could make this move pretty soon, I however cannot promise we can commit to a working stable api that soon ^^'

This looks like an issue i can tackle, let's, see!

[epage]

I'm fine dealing with breakages. Things that would help through them

• An API following semver (might be good to break the API from the CLI since their versioning might need to be independent)
• Document breaking changes

[scrabsha]

An implementation detail that just popped on my head:
Due to how we interact with the Rust API and Cargo, we need to transmit the diagnostics (or any error) generated while performing analysis in the glue crate back to the library entry point. A simple way to achieve it would be to write the invocation result to a temporary file and read it back from the entry point. I'm not sure that every error object we use implements Serialize/Deserialize, though.