Add checking protos to gh CI

.github/workflows/master.yml

@@ -22,6 +22,29 @@ jobs:
         with:
           command: check
 
+  check-protos:
+    name: Check protos
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+
+      - name: Install protobuf
+        run: sudo apt update && sudo apt-get -y install protobuf-compiler
+
+      - name: Generate Rust code from .proto files
+        run: cargo run -p gen-protos
+
+      - name: Check for uncommitted changes
+        run: git diff --exit-code
+
   test:
     name: Test Suite
     runs-on: ubuntu-latest

Cargo.toml

@@ -11,7 +11,7 @@ edition = "2021"
 
 [workspace]
 members = [
-    "gen-protoc",
+    "gen-protos",
     "nekoton-abi",
     "nekoton-contracts",
     "nekoton-derive",

README.md

@@ -21,6 +21,22 @@ cargo add nekoton
 - Rust 1.62+
 - `wasm-pack` 0.9.1+ (to test build for wasm target)
 
+### Modifying protobuffers
+
+Occasionally, you may need to change the `.proto` files that define request/response
+data format. In this case, you will need to add a few steps to the above
+workflow.
+
+- Install the `protoc` compiler.
+- Run `cargo run -p gen-protos` regularly (or after every edit to a `.proto`
+  file).  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 `gen-protos/src/main.rs`.
+
+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.
+
 ## Contributing
 
 We welcome contributions to the project! If you notice any issues or errors, feel free to open an issue or submit a pull request.