Migrate from std::fs::canonicalise to dunce

[ankddev]

The problem

Paths on Windows are hard. Currently we canonicalise paths with std::fs::canonicalise, which has a drawback of making paths UNC paths, so they look like \\\\?\\C:\\Users\\user\\hello.txt (or \\?\C:\Users\user\hello.txt if remove escapes). This allows long paths, but many programs don't play with them well, so we get issues with them. The most recent problem are failing echo integration tests on Windows in the CI (they failed on my Windows machine even before).

Possible solution

We can use dunce crate, which is widely used in the Rust ecosystem. On Windows it tries to canonicalise paths without UNC, and does exactly what std::fs::canonicalise does on other platforms, so there are no problems with it.

Another possible solution

I didn't check, but I've read that std::path::absolute doesn't create UNC paths.

And another solution

We can just manually remove this prefix, like here:

gleam/language-server/src/compiler.rs

Lines 142 to 149 in 2a56ee9

	// Create the source information
	let path = module.src_path.to_string();
	// strip canonicalised windows prefix
	#[cfg(target_family = "windows")]
	let path = path
	.strip_prefix(r"\\?\")
	.map(|s| s.to_string())
	.unwrap_or(path);

---

If this is desired thing, I will work on it

[giacomocavalieri]

People were investigating this on discord and from what I recall this was actually an issue with Node. Are there other places where this canonicalisation resulted in problems?

[ankddev]

I don't know about other problems, but at least from my tests using dunce fixes tests

[lpil]

I think changing something in the compiler to work around a bug in Node seems not great. Could we not upgrade the Node version, or use a different runtime?

[ankddev]

Could we not upgrade the Node version

We can stay on bug-free version for now, but on some point we will need to update anyway. Is this bug reported to Node?

or use a different runtime?

At least those failing tests run on all targets and runtimes, so that's not an option