directory handles: add Dir::metadata

[RalfJung]

Adds a metadata method to the fs::Dir type so that one can fetch the metadata of a directory directly from a handle. This is very similar to File::metadata. In fact we reuse the existing implementation, which reduces code duplication but also is a bit hacky.

r? @the8472
Tracking issue: #120426

[RalfJung]

@bors try jobs=*apple*,*freebsd*,*various*

[the8472]

You need to add the method to the fallback impl in fs::common too.

[RalfJung]

@bors try jobs=*apple*,*freebsd*,*various*,x86_64-msvc*

[the8472]

LGTM, r=me when tests pass

[RalfJung]

Well that's a bit tricky... library/std/src/sys/fs/unix/dir.rs can't construct a Metadata but library/std/src/sys/fs/common.rs can't construct a FileAttr, so there's no signature for fs_imp::Dir::metadata that can be implemented everywhere. Seems like we'll have to make the field of fs::Metadata public (to the crate)?

[the8472]

There's the std-private IntoInner trait, that should let you convert Metadata back into FileAttr.

[RalfJung]

Thanks! I had to add an impl IntoInner<fs_imp::FileAttr> for Metadata, that seems to work. :)

[rust-bors]

💔 Test for ee502b2 failed: CI. Failed jobs:

• try - dist-various-1 (web logs, enhanced plaintext logs)
• try - dist-various-2 (web logs, enhanced plaintext logs)
• try - test-various (web logs, enhanced plaintext logs)

[RalfJung]

@bors try jobs=*various*,*illumos*,*solaris*

[rust-bors]

☀️ Try build successful (CI)
Build commit: 4a57b6c (4a57b6ce18b8120a25096be132fe7908b2fe585f, parent: 9e293ae9f8abecb0be5105787d181518c9012a19)

[RalfJung]

@bors r=the8472

[rust-bors]

📌 Commit 18159d4 has been approved by the8472

It is now in the queue for this repository.