windows: An empty path returns os error 123 instead of os error 3 with recent nightly

[JohnTitor]

I tried this code:

fn main() {
    let path = std::path::Path::new("");
    if let Err(err) = path.canonicalize() {
        println!("{}", err);
        // println!("{:?}", err.kind());
    }
}

I expected to see this happen: canonicalize() returns os error 3 (ERROR_PATH_NOT_FOUND)

Instead, this happened: it returns os error 123 (ERROR_INVALID_NAME)

This is problematic as std::io::ErrorKind doesn't become NotFound but Uncategorized, which isn't useful for most users. Other platforms like Linux return NotFound so the former behavior should be correct here.

Meta

rustc --version --verbose:

rustc 1.58.0-nightly (e249ce6b2 2021-10-30)
binary: rustc
commit-hash: e249ce6b2345587d6e11052779c86adbad626dff
commit-date: 2021-10-30
host: x86_64-pc-windows-msvc
release: 1.58.0-nightly
LLVM version: 13.0.0

The issue doesn't happen on rustc 1.58.0-nightly (e99963c55 2021-10-29), I think the regression was introduced by #89174.

[ChrisDenton]

Thanks for finding and fixing that! I do think that ERROR_INVALID_NAME should be mapped to an ErrorKind. It means "The filename, directory name, or volume label syntax is incorrect". So a syntax error basically.

But I don't think that should block your current PR.

[JohnTitor]

Sounds good, maybe it should be InvalidInput? (EDIT: Opened #90955)

[nbdd0121]

@m-ou-se is it intentional that E-medium is added instead of P-medium?

[m-ou-se]

Oh oops.