Misleading E0583 when attempting to compile a file that includes itself as a module

[9999years]

If we have any file aaa.rs and example.rs in the same directory, where example.rs contains:

mod aaa;
mod example;

Compiling example.rs with rustc example.rs gives an error about being unable to find aaa, rather than an error about example.rs importing itself as a module:

$ rustc example.rs
error[E0583]: file not found for module `aaa`
 --> example.rs:1:5
  |
1 | mod aaa;
  |     ^^^
  |
  = help: name the file either example/aaa.rs or example/aaa/mod.rs inside the directory ""

error: aborting due to previous error

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

The error message with rustc +nightly.

error[E0583]: file not found for module `aaa`
 --> example.rs:1:1
  |
1 | mod aaa;
  | ^^^^^^^^
  |
  = help: to create the module `aaa`, create file "example/aaa.rs"

error[E0583]: file not found for module `example`
 --> example.rs:2:1
  |
2 | mod example;
  | ^^^^^^^^^^^^
  |
  = help: to create the module `example`, create file "example/example.rs"

error[E0601]: `main` function not found in crate `example`
 --> example.rs:1:1
  |
1 | / mod aaa;
2 | | mod example;
  | |____________^ consider adding a `main` function to `example.rs`

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0583, E0601.
For more information about an error, try `rustc --explain E0583`.

I expected to see this happen: rustc give an error about mod example; in example.rs.

Instead, this happened: rustc gave an error about not being able to find the first import in the file relative to example.rs as a module.

The error messages are a little bit better on nightly, but still misleading.

Shell script to reproduce the issue.

#!/usr/bin/env bash
pushd "$(mktemp --directory)" > /dev/null || exit

touch aaa.rs
echo "mod aaa;" > example.rs
echo "mod example;" >> example.rs
rustc example.rs

popd > /dev/null || exit

Meta

rustc --version --verbose:

rustc 1.42.0 (b8cedc004 2020-03-09)
binary: rustc
commit-hash: b8cedc00407a4c56a3bda1ed605c6fc166655447
commit-date: 2020-03-09
host: x86_64-unknown-linux-gnu
release: 1.42.0
LLVM version: 9.0

rustc +nightly --version --verbose:

rustc 1.44.0-nightly (1057dc97a 2020-03-20)
binary: rustc
commit-hash: 1057dc97afce39ff6a224966ece3ed438af4c1f5
commit-date: 2020-03-20
host: x86_64-unknown-linux-gnu
release: 1.44.0-nightly
LLVM version: 9.0

The error messages are the same with RUST_BACKTRACE=1 on the stable and nightly compilers.