In order to support constructing the anchor for multiple pools with a
common anchor height, we must be able to checkpoint each note commitment
tree (and consequently compute the root) at that height. Since we may
not have the information in the tree needed to do so, we require that it
be provided.
As a bonus, this change makes it possible to improve the UX around
spendability, because we will no longer require subtree ranges below
received notes to be fully scanned; the inserted frontier provides
sufficient information to make them spendable.
Neither of these should have been feature flags, as they gate breaking
changes to the Zcash consensus rules (and in some ways are incompatible
with each other), while feature flags should be additive.
This enables us to activate Sapling and NU5 at the same height, to
simplify reuse of test logic between Sapling and Orchard.
As a side-effect, `zcash_extensions` is removed from the workspace
because it enables the `zfuture` feature flag unconditionally, which
breaks workspace-level builds because this causes the `zfuture` feature
flag on `zcash_protocol` to be enabled without the corresponding feature
flag on `zcash_client_sqlite` being enabled. We will fix this by moving
from feature flags to config flags for unstable features.
This change makes it easier for third parties to make use of the Unified
key infrastructure without incurring a dependency upon the rest of the
`zcash_client_backend` interfaces.
Prior to this change, it's necessary to implement the entirety of the
`WalletRead` trait in order to be able to use the input selection
functionality provided by `zcash_client_backend::data_api::input_selection`.
This change factors out the minimal operations required for transaction
proposal construction to better reflect the principle of least authority
and make the input selection code reusable in more contexts.
In order to minimize the operations of the newly-created `InputSource`
and `ShieldingSource` traits, this change also removes the
`min_confirmations` field from transaction proposals, in favor of
storing explicit target and anchor heights. This has the effect of
limiting the lifetime of transaction proposals to `PRUNING_DEPTH -
min_confirmations` blocks.
The MSRV for the main crates is 1.65, which is higher than the Rust
version that stabilised workplace dependencies (1.64). The implicit MSRV
for the component crates is still lower than this, so we don't migrate
these crates.
Kris Nuttycombe
Willem Olding
Jack Grigg
Kris Nuttycombe