zcash_script

Rust bindings to the ECC's zcash_script C++ library.

Developing

This crate works by manually including the zcash_script .h and .cpp files, using bindgen to generate Rust bindings, and compiling everything together into a single library. Due to the way the zcash_script is written we unfortunately need to include a lot of other stuff e.g. the orchard library.

Note that zcash_script (the C++ library/folder inside zcash) uses some Rust FFI functions from zcash; and it also links to librustzcash which is written in Rust. Therefore, when updating zcash_script (this crate), we need to make sure that shared dependencies between all of those are the same versions (and are patched to the same revisions, if applicable). To do that, check for versions in:

• zcash/Cargo.toml in the revision pointed to by this crate (also check for patches)
• librustzcash/Cargo.toml in the revision pointed to by zcash (also check for patches)
• librustzcash/<crate>/Cargo.toml in the revision pointed to by zcash

Updating depend/zcash

We keep a copy of the zcash source in depend/zcash with the help of git subtree. It has one single difference that must be enforced everytime it's updated: the root Cargo.toml must be deleted, since otherwise cargo will ignore the entire folder when publishing the crate (see rust-lang/cargo#8597).

If you need to update the zcash source, run:

git subtree pull -P depend/zcash https://github.com/zcash/zcash.git <ref> --squash

where <ref> is a reference to a branch, tag or commit (it should be a tag when preparing a release, but it will be likely a branch or commit when testing).

The command will likely report a conflict due to the deleted Cargo.toml file. Just run

git rm depend/zcash/Cargo.toml

and then commit the updates. Note: after updating zcash, the PR that includes it must not be squashed-and-merged, due to how subtree works. Otherwise you will get errors when trying to update zcash again.

If that ends up happening, you can always git rm depend/zcash and start over (run the same command as above, but with add instead of pull); our usage of subtree is to just have a convenient way of pulling copies of zcash. (Unfortunately, switching to submodules is not a good solution due to the need of deleting the Cargo.toml.)

Publishing New Releases

Releases for zcash-script are made with the help of cargo release.

Checklist:

• create a new branch batch the release commits into a PR
• update CHANGELOG.md to document any major changes since the last release rust-lang/cargo#8597)
• open a PR to merge your branch into master
• locally run cargo release -- <level> where level can be patch, minor, or major (source)

NOTE: It's important to specify the level when using cargo release because of the way it implements the substitutions. We specify a number of automatic substitutions in Cargo.toml but they will only be applied if cargo release also handles incrementing the version itself, do not increment the version by hand and then run cargo release or cargo release -- release, or it will not correctly update all version references in the codebase.