Specification of the "branch = master" in Cargo.toml breaks the build

[iddm]

Problem

If we have two crates depending on some crate X being a git repository, they should have the dependency:

[dependencies]
x = { git = "<repo>" }

In both crates' Cargo.toml files.
By default, the master branch is taken, according to the documentation.

However, if one crates decides to explicitly mention the branch name, as in

[dependencies]
x = { git = "<repo>", branch = "master" }

Cargo treats these as two different x crates and breaks the symbol compatibility between the two crates: both crates can't work with each other any longer, since they depend on two different crates, even if this is not the case.

In the Cargo.lock file one can observe for the first crate:

[[package]]
name = "first"
version = "0.1.0"
dependencies = [
  "x 99.99.99 (git+https://github.com/x/x?branch=master)",

And for another:

[[package]]
name = "second"
version = "0.1.0"
dependencies = [
 "x 99.99.99 (git+https://github.com/x/x)",

Steps

1. Create a workspace with two crates, depending on some other crate x.
2. In the first crate, depend on the crate x using git and don't specify the branch name.
3. In the second crate, do depend on the crate x using git and specify the branch name.
4. Observe the problem that even though the crate x is actually the same, as per the documentation, if the branch name is omitted the master is taken, and the actual contents are actually the same, the symbols clash and don't merge, the compatibility breaks between the first and the second crates within the same workspace.

Possible Solution(s)

Either forbid the omission of the branch name or revision or somehow make it work.
Note, that the documentation says that it should work:

Since we haven’t specified any other information, Cargo assumes that we intend to use the latest commit on the main branch to build our package. 

Notes

No response

Version

❯ cargo version --verbose
cargo 1.69.0 (6e9a83356 2023-04-12)
release: 1.69.0
commit-hash: 6e9a83356b70586d4b77613a6b33f9ea067b9cdf
commit-date: 2023-04-12
host: x86_64-unknown-linux-gnu
libgit2: 1.5.0 (sys:0.16.0 vendored)
libcurl: 7.86.0-DEV (sys:0.4.59+curl-7.86.0 vendored ssl:OpenSSL/1.1.1q)
os: Arch Linux Rolling Release [64-bit]

[weihanglo]

Thanks for the report and the reproducer! This seems to share the same root cause with #7497 and #11490. We're also tracking changes that need a lockfile version bump in #12120. Close in favor of those :)

[iddm]

Thank you! This indeed looks the same to me as the aforementioned issues, but I can't be exactly sure in that as I don't know the code of cargo and which code paths it takes in all the scenarios. If you are sure it is the same, we can close this issue, no problem! Have a great day!