cargo clean and cargo build fails to handle renamed sub-crate in a workspace

[keepsimple1]

Problem
In a workspace, after doing git mv foo bar to rename a sub-crate, cargo build and cargo clean fails to find renamed sub-crate.

what currently happens:

$ cargo build
error: failed to read `/Users/me/work/foo/Cargo.toml`

Caused by:
  No such file or directory (os error 2)

$ cargo clean
error: failed to read `/Users/me/work/foo/Cargo.toml`

Caused by:
  No such file or directory (os error 2)

what you expected to happen:

cargo build, especially cargo clean can find foo was renamed to bar, and continue to work.

Steps

1. create a Cargo workspace, including at least 2 crates, say app and foo. The root Cargo.toml looks like:

[workspace]
members = [
    "app",
    "foo"
]

app is an application (executable), while foo is a library. The structure looks like this:

├── Cargo.toml
├── app
│   ├── Cargo.toml
│   ├── src
│   │   ├── main.rs
├── foo
│   ├── Cargo.toml
│   ├── src
│   │   ├── lib.rs

2. In the sub-crate foo, its Cargo.toml looks like this:

[package]
name = "foo"
version = "0.1.0"
authors = ["me@gmail.com"]
edition = "2018"

3. build the project using cargo build. It should succeed.

4. rename foo to bar: git mv foo bar .

5. modify root Cargo.toml to replace foo with bar.

6. modify sub-crate Cargo.toml under bar/, to replace foo with bar.

7. Now run cargo build again, or cargo clean. Will see the errors.

Possible Solution(s)
Not a real fix: remove the project and use git to re-pull the project.

Notes
Tried to remove target/ and remove Cargo.lock, did not fix the issue.

Output of cargo version:

cargo 1.51.0 (43b129a 2021-03-16)

[ehuss]

Hm, sorry you're running into that problem. I'm unable to reproduce with the steps given, though. I tried:

mkdir ws9319
cd ws9319
cargo new app
cargo new --lib foo
cat <<EOF > Cargo.toml
[workspace]
members = [
    "app",
    "foo"
]
EOF
cargo build
mv foo bar
sed -i -e 's/foo/bar/g' Cargo.toml
sed -i -e 's/foo/bar/g' bar/Cargo.toml
cargo build

The last step successfully built bar.

Do you maybe have a path dependency on foo somewhere in the workspace?

The error message definitely could be better here.

[keepsimple1]

Thank you for your quick response. Could you please try to add the following and see if the error happens? i.e. use foo from app :

$ cat <<EOF >> app/Cargo.toml
> foo = { version = "0.1", path = "../foo" }
> EOF

$ cat <<EOF > foo/src/lib.rs
> pub fn lib_hello() {
>     println!("hello from lib");
> }
> EOF

$ cat <<EOF > app/src/main.rs
> fn main() {
>     println!("Hello, world!");
>     foo::lib_hello();
> }
> EOF

Thanks!

[ehuss]

Yea, if there is a dependency foo = { version = "0.1", path = "../foo" }, then when the directory is moved, the path in the dependency will also need to be updated to bar = { version = "0.1", path = "../bar" }.

It would be good if the error message pointed to where that dependency is defined.

[keepsimple1]

you are right, my bad, I missed that. Will close this. Thanks!

[ehuss]

If you don't mind, I'm going to reopen this to track improving the error message.

[keepsimple1]

Of course I don't mind. That will be great to improve the error message. Thanks!