Fetch directly from crates.io if given a crate name

[thesamesam]

It'd be nice if pycargoebuild could fetch directly from crates.io when given a crate name.

This would be useful for two reasons:

1. Laziness: right now, I have to grab whatever the ebuild would fetch, unpack it, then run pycargoebuild inside. Lots of effort.
2. Required for some software: pkgcraft-c's Cargo.toml refers to pkgcraft via a path (../pkgcraft) which neither pycargoebuild nor cargo-ebuild handle properly. Neither end up listing pkgcraft as a dependency. The version downloaded from crates.io does list it properly because cargo mangles it first on upload (or crates.io mangles it before publishing, whatever).

(If you don't like the general idea, consider this a bug report for 2., in that pycargoebuild can't handle pkgcraft-c because of the relative path dep.)

[gyakovlev]

You don’t need to pre-fetch generally.
Just
cd pkgcraft-c && cargo_src_compile
You dont want to use crate tarball for workspace/vendored source like this, that’s why it’s omitted from CRATES

[mgorny]

I suppose this could be done in two steps:

1. Support specifying URL instead of directory, and unpack it to tmpdir.
2. Support specifying crate name instead of URL.

Am I missing something?

[thesamesam]

No, I think you're spot on. Both would be helpful and then together, it solves my bother.

[mgorny]

So after spending >1 hour on implementing this, I'm stuck because crates don't have Cargo.lock.