librustzcash now requires a minimum of Rust 1.36.0.
The proc-macro2, quote, syn, and unicode-xid dependencies are pulled in
because we moved to using ff_derive inside pairing to derive the
BLS12-381 fields. We will be going back to explicit implementations with
the jubjub and bls12_381 crates, so these dependencies will disappear
once that is done.
The autocfg crate is pulled in by the upgraded num-integer crate, which
is transitively used by fpe. Rewriting fpe to not use num-bigint would
drop:
- autocfg
- num-bigint
- num-integer
- num-traits
We primarily depend on rand_core in our crates. The rand crate, and its
other dependencies, are pulled in for two reasons:
- The group crate exposes testing helper functions in its public API
that use distribution sampling APIs in the rand crate.
- zcash_primitives::transaction::Builder uses rand::seq::SliceRandom to
shuffle the order of Sapling spends and outputs.
Refactoring these in order to drop rand would additionally drop:
- c2-chacha
- rand_chacha
- rand_hc
- rand_xorshift
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