Switch `rust-bitcoin` dependencies

[nymius]

bitcoin crate is working towards its next release. In the process, it began outsourcing and isolating components that were previously tightly integrated with the original crate.

Shall we start migrating from bitcoin as a dependency towards the newer smaller crates when possible?

I have the following in mind:

• bitcoin-primitives
• bitcoin-network-kind
• psbt-v2
• bitcoin-units

[apoelstra]

It's probably not possible to update piecemeal because all the types' APIs reference each other.

Furthermore, it's probably impossible for bdk to move until rust-miniscript does. There have been a couple attempts at this but we're struggling because we broke the Script type, which rust-miniscript depends on heavily.

In rust-bitcoin we hope that we can come up with a transition plan and then backport it piecemeal into 0.32.x (which bdk currently uses). For example, we have a new bitcoin-consensus-encoding crate which redoes our encoding traits, optimizing and simplifying a bunch of stuff (and totally getting rid of bitcoin-io for users who don't care about no-std io). It would be straightforward enough for us to release a version of 0.32.x which uses the new traits, and at that point bdk can move toward it.

[tnull]

I also want to note that if BDK updates, LDK's dependent projects will be forced to upgrade too. So as per Nashville agreement, it would be great if we could hold off upgrading until we're certain the extended ecosystem can follow, essentially in one large coordinated effort (which thankfully should be much easier by now, as most tasks/code changes should just be easily doable by agents).

[nymius]

Thanks for jumping in. No intention to move out of what has already been discussed, we were talking mainly about psbt-v2 in its version 0.3.0, which is by very little not exactly bitcoin@0.32.8 psbt module. That lead to talking about the other crates and I was documenting that here.