incompatible types when using re-exports of the same crate from different crates (different paths)

[dustbort]

I tried this code:

let item = sickle_builder::types::time::Date::from_calendar_date(
    2020,
    sickle_builder::types::time::Month::January,
    1,
)?;
let y: i32 = item.year();
let m: tiberius::time::time::Month = item.month();
let d: u8 = item.day();
let date: tiberius::time::Date = tiberius::time::time::Date::from_calendar_date(y, m, d)?;

I expected to see this happen: No error

Instead, this happened:

error[E0308]: `?` operator has incompatible types
  --> sickle-query/src/mssql_queryable.rs:53:21
   |
53 |                     tiberius::time::time::Date::from_calendar_date(y, m, d)?
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected struct `tiberius::time::Date`, found struct `sickle_builder::types::time::Date`
   |
   = note: `?` operator cannot convert from `sickle_builder::types::time::Date` to `tiberius::time::Date`

sickle_query::types::time and tiberius::time are re-exports of the time crate. For multiple reasons, these may be different versions with different features and are not be assumed to be the same. However, it seems that rustc is detecting that they are the same crate, and then "forgets" the path or assumes the wrong path on line 53. But though the path is explicitly given on both the left and right hand sides of the assignment, so there is no ambiguity.

Confirmed this for nightly with cargo +nightly build --workspace --all-targets --all-features

Note: This seems different than #102882, because I am explicitly stating the paths of which re-export to use, and am not making assumptions that they are the same. rustc seems to arbitrarily pick/unify/dedup a different re-export than what is explicitly stated on one side of the assignment, then fails to do the same with the other side.

Meta

rustc --version --verbose:

rustc 1.65.0 (897e37553 2022-11-02)
binary: rustc
commit-hash: 897e37553bba8b42751c67658967889d11ecd120
commit-date: 2022-11-02
host: x86_64-unknown-linux-gnu
release: 1.65.0
LLVM version: 15.0.0

Backtrace

No backtrace; it doesn't build.

[albertlarsan68]

What is the output of cargo tree --duplicates --workspace ?

[dustbort]

@albertlarsan68 It outputs nothing. I also tried cargo tree --duplicates --workspace --all-features with same result.

[dustbort]

It's also interesting that I tried using std::mem::transmute to see if rustc is really looking up the wrong definition for the RHS, and it is, because I got an error that the two structs are different sizes on the LHS and RHS. The error still shows the RHS coming from the sickle_builder crate instead of tiberius.
For example:

let date: tiberius::time::Time = unsafe { std::mem::transmute(tiberius::time::time::Time::from_hms_micro(hour, minute, second, microsecond)?) };

[Enselic]

Triage: Thanks for reporting. To make progress we're going to need a reproducer that others can try. Preferably a minimal reproducer.