Assume the following file structure:

src
  bin
    foo.rs
  bar
    baz.rs
  bar.rs
  main.rs

where bar.rs has a mod baz; in it.

When doing

mod bar;

in main.rs, everything works like expected. The bar module is loaded from bar.rs and its baz module gets loaded from bar/baz.rs. Smooth sailing.

Now try adding

#[path = "../bar.rs"]
mod bar;

to bin/foo.rs. What I expected was that this would behave exactly identical to mod bar in main.rs; after all, I've just changed the implicit location of bar.rs to an explicit one.

Instead, this happens:

error[E0583]: file not found for module `baz`
 --> src\bin\..\bar.rs:1:1
  |
1 | mod baz;
  | ^^^^^^^^
  |
  = help: to create the module `baz`, create file "src\bin\..\baz.rs" or "src\bin\..\baz\mod.rs"

For more information about this error, try `rustc --explain E0583`.

Why is it looking for src\bin\..\baz.rs? It should be looking for src\bin\..\bar\baz.rs, since bar.rs is not a root module like lib.rs or main.rs, nor is it a mod.rs file.

If this behavior is expected, it's not very well documented, I certainly couldn't find anything explaining this behavior in the documentation.

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-pc-windows-msvc
release: 1.65.0
LLVM version: 15.0.0