pub mod foo {
    pub use dep1::foo as dep1;
}

pub mod foo {}

error[E0432]: unresolved import `dep1::foo`
 --> src/lib.rs:2:13
  |
2 |     pub use dep1::foo as dep1;
  |             ^^^^^^^^^^^^^^^^^ no `foo` in `foo`

error[E0659]: `dep1` is ambiguous (name vs any other name during import resolution)
 --> src/lib.rs:2:13
  |
2 |     pub use dep1::foo as dep1;
  |             ^^^^ ambiguous name
  |
  = note: `dep1` could refer to a crate passed with `--extern`
  = help: use `::dep1` to refer to this crate unambiguously
note: `dep1` could also refer to the module imported here
 --> src/lib.rs:2:13
  |
2 |     pub use dep1::foo as dep1;
  |             ^^^^^^^^^^^^^^^^^
  = help: use `self::dep1` to refer to this module unambiguously

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0432, E0659.
For more information about an error, try `rustc --explain E0432`.

rustc 1.47.0-beta.9 (d6646f647 2020-10-03)
binary: rustc
commit-hash: d6646f64790018719caebeafd352a92adfa1d75a
commit-date: 2020-10-03
host: x86_64-unknown-linux-gnu
release: 1.47.0-beta.9
LLVM version: 11.0

rustc 1.49.0-nightly (beb5ae474 2020-10-04)
binary: rustc
commit-hash: beb5ae474d2835962ebdf7416bd1c9ad864fe101
commit-date: 2020-10-04
host: x86_64-unknown-linux-gnu
release: 1.49.0-nightly
LLVM version: 11.0