8ec3571d80 Implement GetKey for Vec<Xpriv> (Nadav Ivgi)
Pull request description:
It appears that the `BTreeSet<Xpriv>`/`HashSet<Xpriv>` sets currently implementing `GetKey` cannot actually be constructed, because `Xpriv` does not implement `Ord` nor `Hash`. (And that the rust-bitcoin code referencing these sets should not even compile? yet evidently it does 👀 )
This PR adds support for `Vec<Xpriv>` to enable signing with multiple `Xpriv`s, but does not address the issue with the existing sets.
The added test case demonstrates the issue:
```rust
error[E0277]: the trait bound `bip32::Xpriv: std:#️⃣:Hash` is not satisfied
--> bitcoin/src/psbt/mod.rs:2301:24
|
2301 | HashSet::new().insert(xpriv.clone());
| ^^^^^^ the trait `std:#️⃣:Hash` is not implemented for `bip32::Xpriv`
|
note: required by a bound in `std::collections::HashSet::<T, S>::insert`
--> /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/std/src/collections/hash/set.rs:888:5
error[E0277]: the trait bound `bip32::Xpriv: Ord` is not satisfied
--> bitcoin/src/psbt/mod.rs:2302:25
|
2302 | BTreeSet::new().insert(xpriv.clone());
| ^^^^^^ the trait `Ord` is not implemented for `bip32::Xpriv`
|
note: required by a bound in `std::collections::BTreeSet::<T, A>::insert`
--> /rustc/82e1608dfa6e0b5569232559e3d385fea5a93112/library/alloc/src/collections/btree/set.rs:899:5
```
ACKs for top commit:
apoelstra:
ACK 8ec3571d80 successfully ran local tests
tcharding:
ACK 8ec3571d80
Tree-SHA512: aceb95f8eaf11f91c6829e0b5e1c0264ebffbf587fd420145a22e924cb45678b2f4334f0b7de6ed99b57f0ce24c3d61f9e5c1e348e1b40975bc515e8fd16b75d