Incorrect [root] in Cargo.lock when using workspaces

[debris]

I have a project with several (10+) local libraries

…
├── Cargo.toml
├── src
├── sub1
│   ├── Cargo.toml
│   ├── src
├── sub2
│   ├── Cargo.toml
│   ├── src

My Cargo.toml looks like this.

[project]
name = "foo"
version = "0.1.0"
authors = []

[dependencies]
sub1 = { path = "sub1" }
sub2 = { path = "sub2" }

After adding [workspace] to the end of Cargo.toml

[project]
name = "foo"
version = "0.1.0"
authors = []

[dependencies]
sub1 = { path = "sub1" }
sub2 = { path = "sub2" }

[workspace]

All of my dependencies compile as a part of my workspace (as expected). But what's strange, foo is no longer a [root] in my Cargo.lock file. Instead sub1 is. Is it intended behaviour?

[alexcrichton]

Indeed! The [root] in Cargo.lock is basically just backwards compatibility at this point. We essentially just had to deterministically choose a crate to go there. Shouldn't affect any usage of Cargo though!

[debris]

Shouldn't affect any usage of Cargo though!

That's right. It only affects one of the tools I'm using - cargo-graph.
I've created the issue over there. kbknapp/cargo-graph#33

[alexcrichton]

Ok, thanks!

[behnam]

@alexcrichton, was there any reason to not use the workspace root as the lock root, at least for cases where workspace Cargo.toml is combined with a package? If not, is it still possible to make this happen, or is it too late?

At the moment, there's no way to find the workspace root looking only at the lock file, which is kind of unexpected and demands extra work for tools, like cargo-graph, to figure it out.

[alexcrichton]

Unfortunately that'd make a backwards incompatible change at this point :(

[remram44]

Honestly I think the [root] should either be removed or fixed. There is no point keeping it "for compatibility" if compatibility has been broken. Either cargo-graph shouldn't use this (but why not use this if it's present?) or the correct info should be written to Cargo.lock.

[remram44]

After #4571, Cargo no longer includes [root] in the lock file. This makes cargo-graph even more broken. (I have updated my patch)