* Redesign Sapling data model for V5 shared anchor and spends
The shared anchor is only present if there are any spends.
As part of this change, delete the manual PartialEq impl and its tests,
because we can derive PartialEq now.
* Stop creating a temporary Vec for the spend and output iterators
* Rename TransferData variants
Interactive rename using the following commands:
```sh
fastmod Spends SpendsAndMaybeOutputs
fastmod NoSpends JustOutputs
```
* Refactor out common sprout nullifier code
* Implement the AtLeastOne constrained vector type
This vector wrapper ensures that it always contains at least one element.
* Simplify Sapling TransferData using AtLeastOne
Also update the RFC to use AtLeastOne for Orchard.
* add sapling shielded data to transaction V5
* implement nullifiers
* test v5 in shielded_data_roundtrip
* Explicitly design serialization for Transaction V5
Implement serialization for V4 and V5 spends and outputs, to make sure
that the design works.
* Test serialization for v5 spends and outputs
Also add a few missing v4 tests.
* Delete a disabled proptest
* Make v5 transactions a top-level heading
And add a missing serialized type.
* Fix a comment typo
* v5 transaction RFC: split array serialization
Based on #2017
* RFC: explicitly describe serialized field order
And link to the spec
* RFC: add the shared anchor serialization rule test
Co-authored-by: teor <teor@riseup.net>
* start refactoring transaction v4 for transaction v5
- move ShieldedData to sapling
- add AnchorVariant
- rename shielded_data to sapling_shielded data in V4
- move value_balance into ShieldedData
- update prop tests for new structure
* add AnchorVariant to Spend
- make anchor types available from sapling crate
- update serialize
* change shielded_balances_match() arguments
* change variable name anchor to shared_anchor in ShieldedData
* fix empty value balance serialization
* use AnchorV in shielded spends
* Rename anchor to per_spend_anchor
* Use nullifiers function directly in non-finalized state
* Use self.value_balance instead of passing it as an argument
* Add missing fields to ShieldedData PartialEq
* Derive Copy for tag types
* Add doc comments for ShieldedData refactor
* Implement a per-spend anchor compatibility iterator
Co-authored-by: teor <teor@riseup.net>
teor
Alfredo Garcia