tidy: make rustc dependency error less confusing

[RalfJung]

The current wording leads to very confusing messages:

tidy error: Dependencies for main workspace not explicitly permitted:
* unicode-ident 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)

Miri is part of that workspace, and there never was a problem adding Miri dependencies. The actual error is that due to a crate bump this now showed up as a rustc dependency, and those are restricted.

[rust-highfive]

r? @jyn514

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[RalfJung]

(FWIW, the function names here are not very helpful. check_dependencies sounds like it could be the function that checks the licenses of all dependencies, but it isn't. The license checking function is called check_exceptions...)

[jyn514]

Miri is part of that workspace, and there never was a problem adding Miri dependencies. The actual error is that due to a crate bump this now showed up as a rustc dependency, and those are restricted.

This doesn't match my reading of the code. It runs cargo metadata from the top level directory, which shows all dependencies in the workspace, no?

[RalfJung]

Yeah I had to read the code 3 times to figure out what happens.

It only checks the dependencies of RESTRICTED_DEPENDENCY_CRATES, which is only rustc.

[jyn514]

The new names make the code a lot easier to understand, thanks :)

@bors r+ rollup

[bors]

📌 Commit 79ad594 has been approved by jyn514

It is now in the queue for this repository.