Keep a changelog

[RazrFalcon]

As an author of a cargo plugin, it's extremely hard to update to a newer cargo version, since changes are undocumented.

The only "solution" is to look up in commits history and git blame.

[matklad]

@RazrFalcon we don't really officially support using Cargo as a library, it is 0.x and unstable. Would it be possible to use tools like cargo metadata or --message-format=json (docs) for your plugin? These are interfaces which are guaranteed to be stable.

[RazrFalcon]

I see. I have to run the build process thought my plugin, so I need an access to the core::compiler::Compilation struct. And I'm not sure it's possible via cargo metadata.

[matklad]

@RazrFalcon yep, metadata won't help with Compliation. However cargo build --message-format=json or cargo +nightly build --build-plan -Z unstable-options (currently unstable, https://doc.rust-lang.org/beta/cargo/reference/unstable.html#build-plan) might help

[RazrFalcon]

Will give it a try.

By the way, is this ok that json output is malformed?

[matklad]

No, it is not ok :) --message-format and --build-plan should have stdout as a series of newline separated JSON objects (we use that instead of a single array to allow streaming), and nothing else should be printed to stdout.

[RazrFalcon]

Oh, I see. Than it's fine.

[RazrFalcon]

Hi. I've tried to use the json output and looks like it will be enough for my needs. The current problem is that I don't know how to get Compilation::target_dylib_path, aka the dir that contains rust std libraries. Can I get it via cli?