Tracking issue for RFC 2295, "Extend Pattern API to OsStr"

[Centril]

This is a tracking issue for the RFC "Extend Pattern API to OsStr" (rust-lang/rfcs#2295, revised in rust-lang/libs-team#311).

Steps:

• Implement the RFC (cc @kennytm)
• Adjust documentation (see instructions on forge)
• Stabilization PR (see instructions on forge)

Unresolved questions:

None

[kennytm]

Status update: I've got the implementation of this ready, but I'd like to wait for a decision on rust-lang/rfcs#2500 first, as I believe this isn't an urgent feature.

Without the pattern API part, this RFC will only provide the slicing operation (os_str[a..b]), which (1) is insta-stable as requires impl Index for OsStr, (2) the only indices that guaranteed to be valid are 0 and os_str.len(), and (3) slows down PartialEq/PartialOrd without much to return.

[1011X]

Now that rust-lang/rfcs#2500 has merged, can this RFC be implemented?

[DutchGhost]

@rustbot claim