Impl PartialEq/Ord<str/String> for Path[Buf]

[gkoz]

Sorry for revisiting this: when preparing #31751 I was still assuming that the <str> impls are already there. So currently OsStr can be compared to str and Path cannot. This seems both inconsistent and inconvenient.

I'm likely blind to some drawbacks and/or going over the top with combinations here. Could some of them be replaced with blanket impls for T: AsRef<Path>?

It would help if there was a coordinating issue for libstd trait impls with some goals, dos and don'ts.

[rust-highfive]

r? @aturon

(rust_highfive has picked a reviewer for you, use r? to override)

[gkoz]

Apparently this patch causes

src/libcollectionstest/btree/set.rs:226:20: 226:31 error: the trait `core::cmp::PartialEq<&str>` is not implemented for the type `str` [E0277]

src/libcollectionstest/btree/set.rs:226             self.0.partial_cmp(&other.0)

                                                           ^~~~~~~~~~~

I'm not yet sure how exactly.

[gkoz]

Okay, with nightly becoming 1.9 in a few days this would have to be rewritten anyway.