Delete Cargo.lock from this repo

[alexcrichton]

There's now a lock file upstream in rust-lang/rust so the one here isn't
actually used, and otherwise this crate is used as a dependency so the lock file
isn't respected anyway!

[rust-highfive]

r? @matklad

(rust_highfive has picked a reviewer for you, use r? to override)

[bors]

☔ The latest upstream changes (presumably #4624) made this pull request unmergeable. Please resolve the merge conflicts.

[matklad]

Ok, so this is how it works now, right?

1. In rust-lang/rust repo, cargo is included as a submodule under tools/cargo.
2. It is also included as a workspace member, which gives it the actual lockfile.
3. When filing a PR against rust-lang/rust, Cargo test suite is executed. Also, RLS, which depends on Cargo, is tested as well.
4. When filing a PR against rust-lang/cargo, RLS is not tested. Only when the Cargo submodule is updated we'll learn if it actually works.

I am a bit worried about two things:

1. Looks like CI for Cargo now is not actually complete, because ideally we'd want to test with rust-lang/rust lockfile.

2. Including Cargo as a workspace member does not seem entirely right for me because in theory Cargo should be a complete separate piece of software, with its own lockfile, and it could be a workspace itself even.

Not that I think there will be any real significant problems because of this, so r+ from me! (but there's a merge conflict).

[alexcrichton]

@matklad you're correct on all counts! It's true that Cargo's CI is less comprehensive than Rust's, and it's true that different versions of dependencies are used. That being said though I think it's an undesriable goal for the two to exactly match up. The Rust CI is very comprehensive and trying to match it on Cargo likely mostly just amount to a waste of resources.

It's true that from time to time we'll have a bug sneak in that will make updating the submodule in rust-lang/rust more difficult (especially with the RLS) but so far it hasn't been too much of a problem in practice and I'd probably expect that to stay mostly the same over time.

[alexcrichton]

Oh also note that we use a workspace with Cargo to ensure that we only build Cargo once with one the same version of all deps between the RLS and Cargo itself.

[alexcrichton]

@bors: r=matklad

[bors]

📌 Commit 5c9665f has been approved by matklad

[bors]

⌛ Testing commit 5c9665f with merge b73cc00e704f04ddcdf180da71898e9f7de1f5a1...

[bors]

💥 Test timed out

[matklad]

@bors r+

[bors]

💡 This pull request was already approved, no need to approve it again.

• This pull request previously failed. You should add more commits to fix the bug, or use retry to trigger a build again.

[bors]

📌 Commit 5c9665f has been approved by matklad

[bors]

⌛ Testing commit 5c9665f with merge 92a3a4e...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: matklad
Pushing 92a3a4e to master...