contributing.md: docs on working with protos

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Ilya Grigoriev 2023-04-09 22:28:51 -07:00
parent 7d9faef95f
commit e448198530

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@ -130,3 +130,25 @@ These are listed roughly in order of decreasing importance.
6. To run tests more quickly, use `cargo nextest run --workspace`. To
use `nextest` with `insta`,
use `cargo insta test --workspace --test-runner nextest`.
## Modifying protobuffers (this is not common)
Occasionally, you may need to change the `.proto` files that define jj's data
storage format. In this case, you will need to add a few steps to the above
workflow.
- Install the `protoc` compiler. This usually means either `apt-get install
protobuf-compiler` or downloading [an official release]. The
[`prost` library docs] have additional advice.
- Run `cargo run -p gen-protos` regularly (or after every edit to a `.proto`
file). This is the same as running `cargo run` from `lib/gen-protos`. The
`gen-protos` binary will use the `prost-build` library to compile the
`.proto` files into `.rs` files.
- If you are adding a new `.proto` file, you will need to edit the list of
these files in `lib/gen-protos/src/main.rs`.
[an official release]: https://github.com/protocolbuffers/protobuf/releases
[`prost` library docs]: https://docs.rs/prost-build/latest/prost_build/#sourcing-protoc
The `.rs` files generated from `.proto` files are included in the repository,
and there is a Github CI check that will complain if they do not match.