cargo fmt fails to format code when using symlinks

When symlinking a file, it looks like cargo fmt isn't able to properly resolve modules. It causes cargo fmt to ignore certain modules referenced by that symlinked file.

Here's a minimal reproducable example:

.
├── Cargo.toml
├── linked
│   ├── Cargo.toml
│   └── src
│       ├── main.rs -> ../../plain/src/main.rs
│       └── unformatted.rs
└── plain
    ├── Cargo.toml
    └── src
        ├── main.rs
        └── unformatted.rs

==> ./Cargo.toml <==
[workspace]
resolver = "2"
members = [ "plain", "linked" ]

==> ./linked/Cargo.toml <==
[package]
name = "linked"
version = "0.1.0"
edition = "2024"

[dependencies]

==> ./linked/src/unformatted.rs <==
pub fn unformatted() { println!("Hello from linked!"); }

==> ./plain/Cargo.toml <==
[package]
name = "plain"
version = "0.1.0"
edition = "2024"

[dependencies]

==> ./plain/src/main.rs <==
mod unformatted;

fn main() {
    unformatted::unformatted();
}

==> ./plain/src/unformatted.rs <==
pub fn unformatted() { println!("Hello from plain!"); }

cargo fmt only formats the plain file by default. You have to explicitly pass linked/src/unformatted.rs to cargo fmt to format it.

> cargo fmt --check
Diff in plain/src/unformatted.rs:1:
-pub fn unformatted() { println!("Hello from plain!"); }
+pub fn unformatted() {
+    println!("Hello from plain!");
+}
 
> cargo fmt --check -- linked/src/unformatted.rs
Diff in plain/src/unformatted.rs:1:
-pub fn unformatted() { println!("Hello from plain!"); }
+pub fn unformatted() {
+    println!("Hello from plain!");
+}
 
Diff in linked/src/unformatted.rs:1:
-pub fn unformatted() { println!("Hello from linked!"); }
+pub fn unformatted() {
+    println!("Hello from linked!");
+}

The rust code itself is working as expected:

> cargo run --manifest-path linked/Cargo.toml
Hello from linked!
> cargo run --manifest-path plain/Cargo.toml
Hello from plain!

Reproduce the minimal workspace shown in the issue, including the symlink from linked/src/main.rs to plain/src/main.rs. Run cargo fmt --check with and without the explicit linked file path, then trace how rustfmt discovers modules through symlinked files. Done means the default command formats both referenced modules without requiring an explicit path.