fix: std::sys::fs use_with_native_path for read_dir for windows

[WrldEngine]

Fix the read_dir function in windows for using with native_path

r? @ChrisDenton

[rustbot]

r? @Mark-Simulacrum

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[hkBst]

@rustbot label +O-windows

[hkBst]

cc @ChrisDenton

[rustbot]

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[ChrisDenton]

This does not seem to fix the issue. It just converts the path to wide and then back again, which is a quite expensive no-op.

View changes since this review

[WrldEngine]

This does not seem to fix the issue. It just converts the path to wide and then back again, which is a quite expensive no-op.

View changes since this review

But it is beginning of fixing the purpose using this function on all platforms. I covered it on windows, expensive no-op it is the function 'use_with_native_path' at all

[ChrisDenton]

The purpose of the fixme is to clearly show that there's an issue to be fixed. This PR doesn't fix the issue, it merely hides the issue one level deeper and removes the fixme note.

The performance impact of this is why it's a fixme instead of being implemented that way to start with.

[WrldEngine]

The purpose of the fixme is to clearly show that there's an issue to be fixed. This PR doesn't fix the issue, it merely hides the issue one level deeper and removes the fixme note.

The performance impact of this is why it's a fixme instead of being implemented that way to start with.

I didnt remove fixme comment
Functionality use_with_native_path is useless itself, and making that no need level, what you said
Better without fixme comments than with itself

Also i see some moments like:

pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
    // FIXME: use with_native_path on all platforms
    #[cfg(not(windows))]
    return imp::copy(from, to);
    #[cfg(windows)]
    with_native_path(from, &|from| with_native_path(to, &|to| imp::copy(from, to)))
}

is it also expensive no-op?
I could fully rewrite readdir function for processing with WCStr, to avoid performance issues, if you agree

[ChrisDenton]

Yes, if readdir can be rewritten so that it doesn't convert pack to a Path then that would address my concerns.

[WrldEngine]

@ChrisDenton Can you check now? I removed Path, but couldnt avoid from PathBuf because of DirEntry display info