'expected struct `cargo_metadata::Package`, found a different struct `cargo_metadata::Package`' should note that one is a module and one is a crate

[jyn514]

error[E0308]: mismatched types
  --> src/utils/cargo_metadata.rs:50:9
   |
50 |         &self.root
   |         ^^^^^^^^^^ expected struct `cargo_metadata::Package`, found a different struct `cargo_metadata::Package`
   |
   = note: expected reference `&cargo_metadata::Package` (struct `cargo_metadata::Package`)
              found reference `&cargo_metadata::Package` (struct `cargo_metadata::Package`)

It's impossible to tell here whether it found the version from the current module, crate::utils::cargo_metadata, or the one from the crate, ::cargo_metadata. It would be nice to at least say why they might be different, the same way the compiler warns about two versions of a crate.

(I feel like I reported this bug already, but I can't seem to find it.)

[camelid]

Looks the error is produced here:

rust/compiler/rustc_middle/src/ty/error.rs

Lines 83 to 95 in 11c94a1

	fn report_maybe_different(
	f: &mut fmt::Formatter<'_>,
	expected: &str,
	found: &str,
	) -> fmt::Result {
	// A naive approach to making sure that we're not reporting silly errors such as:
	// (expected closure, found closure).
	if expected == found {
	write!(f, "expected {}, found a different {}", expected, found)
	} else {
	write!(f, "expected {}, found {}", expected, found)
	}
	}

[pierwill]

@rustbot claim

[camelid]

@pierwill Note that this issue will likely be tricky to fix!

[pierwill]

Flew too close to sun again.

[camelid]

Flew too close to sun again.

That's okay! I've been working on rustc for months now and I don't think I know how to fix this issue :)