Currently we have a few things mixed up in the feature gating of
`hashes`.
Observe that:
- `io::Write` is not related to allocation.
- "std" should be able to enable "alloc".
Improve feature gating by doing:
- Enable "alloc" from "std" and simplify `cfg` codebase wide.
- Enable "internals/alloc" from "alloc".
- Fix feature gating to use the minimal requirement i.e., "alloc".
It is easier to maintain code if macros use the fully qualified path to
types and functions instead of relying on code that uses the macro to
import said type or function.
The `ToHex` trait was replaced by either simple `Display`/`LowerHex`
where appropriate or `DisplayHex` from `bitcoin_internals` which is
faster.
This change replaces the usages and removes the trait.
We would like to bring the `bitcoin_hashes` crate into the
`rust-bitcoin` repository.
Import `bitcoin_hashes` into `rust-bitocin/hashes`, doing so looses all
the commit history from the original crate but if we archive the
original repository then the history will be preserved. We maintain the
same version number obviously and in the changelog we note the change of
repository.
Commit hash that was tip of `bitcoin_hashes` at time of import:
commit 54c16249e06cc6b7870c7fc07d90f489d82647c7
Includes making `embedded` and `fuzzing` per-crate i.e., move them into
`bitcoin` as hashes includes these also.
NOTE: Does _not_ enable fuzzing for `hashes` in CI.
Notes on CI:
Attempts to merge in the github actions from the hashes crate however reduces
coverage by not running hashes tests for beta toolchain. Some additional
work could be done to improve the CI to increase efficiency without
reducing coverage. Leaving for another day.