Mismatched type for cyclic dev-dependency on same crate

[lausek]

Repository @kaichaosun

See above link for minimal viable example. There are two crates, one is test-utils, another is client. This is the client code with a dev-dependency on test-utils:

#[derive(Eq, PartialEq, Debug)]
pub struct Name {
	pub first_name: String,
	pub last_name: String,
}

pub fn full_name(first: String, last: String) -> Name {
	Name {
		first_name: first,
		last_name: last,
	}
}

mod test {
	use super::*;

	#[test]
	fn full_name_works() {
		assert_eq!(
			full_name(String::from("hello"), String::from("world")), 
			test_utils::helper()
		)
	}
}

This is test-utils code with a dependency on client:

use client::Name;

pub fn helper() -> Name {
	Name {
		first_name: String::from("hello"),
		last_name: String::from("world"),
	}
}

Running cargo test (cargo test +stable) in the workspace shows this error:

error[E0308]: mismatched types
  --> client/src/lib.rs:19:3
   |
19 |           assert_eq!(
   |  _________^
20 | |             full_name(String::from("hello"), String::from("world")),
21 | |             test_utils::helper()
22 | |         )
   | |_________^ expected struct `Name`, found struct `client::Name`

I expect this code to correctly determine that the types are compatible, because they effectively reference the same crate.

Meta

rustc --version --verbose:

rustc 1.49.0-nightly (5404efc28 2020-11-11)
binary: rustc
commit-hash: 5404efc28a0cddee103ef6396c48ea71ff9631c8
commit-date: 2020-11-11
host: x86_64-unknown-linux-gnu
release: 1.49.0-nightly

Other Issue: #59305
Discussion on Rust forum: https://users.rust-lang.org/t/cyclic-dev-dependency-get-type-mismatch-error/48391/1

[camelid]

Do you know if this is a regression; i.e., if it used to work?

[lausek]

Do you know if this is a regression; i.e., if it used to work?

No, I'm not aware of this code being able to function.