Repository: rust
Issue: Tracking Issue for `windows_change_time`
Labels: T-libs-api,C-tracking-issue

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In Windows, there's a field in FILE_BASIC_INFO called ChangeTime that tracks when file metadata is changed, such as renaming, file attributes, etc.

Currently, this property isn't included in the ::sys::windows::fs::FileAttr implementation, but is available in the c::FILE_BASIC_INFO impl.

Last write time (which is currently provided) is the last time the data stream changed, and this value represents a different time value.

[source](https://devblogs.microsoft.com/oldnewthing/20100709-00/?p=13463#:~:text=I%E2%80%99m%20told%20that%20the%20difference%20is%20metadata.%20The,attributes%20%28hidden%2C%20read-only%2C%20etc.%29%20or%20renaming%20the%20file.)

This change adds a method `change_time()` to the `MetadataExt` trait in order to provide this value.

### Public API

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```rust
fn windows_change_time() {
    let meta = std::fs::metadata("example.txt").unwrap();

    // Returns Option<u64> since this is only available if FILE_BASIC_INFO is the backing type of `.inner()`
    let change_time = meta.change_time();
}
```

### Steps / History

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- [x] Implementation: #112328
- [ ] Final comment period (FCP)[^1]
- [ ] Stabilization PR

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### Unresolved Questions

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- None yet.

[^1]: https://std-dev-guide.rust-lang.org/feature-lifecycle/stabilization.html