`file!()` returns incorrect `Path`s on WASM target built on Windows.

Here is a minimal reproducible example: https://github.com/andriyDev/wasm-path-error

The file!() macro produces nonsensical paths for WASM built on Windows.

On Windows, file!() in src/lib.rs produces src\\lib.rs with the components ["src", "lib.rs"].

I would expect file!() to produce the same set of components on WASM. However, on WASM built on Windows, file!() in src/lib.rs produces src\\lib.rs with the components ["src\\lib.rs"].

It seems that the path is not translated appropriately from Windows to WASM.

Meta

rustc --version --verbose:

rustc 1.85.0 (4d91de4e4 2025-02-17)
binary: rustc
commit-hash: 4d91de4e48198da2e33413efdcd9cd2cc0c46688
commit-date: 2025-02-17
host: x86_64-pc-windows-msvc
release: 1.85.0
LLVM version: 19.1.7

Additional Context

This is relevant for https://github.com/bevyengine/bevy/issues/14246. We are using the file path to refer to an asset in the src directory, but due to the incorrect components, we can't remove the src prefix.

Start with the linked minimal reproduction and run the file!() case from src/lib.rs on a Windows-built WASM target, comparing its path components with the native result. Trace the file!() macro's handling of the emitted path across the Windows-to-WASM boundary. Done means the WASM result has separate src and lib.rs components, matching the expected behavior.