ci: verify that codegen is up-to-date

Author: mahkoh

.github/workflows/codegen.yml

@@ -0,0 +1,26 @@
+name: codegen
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+  workflow_dispatch:
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  codegen:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v7
+    - name: Install
+      run: |
+        curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain nightly
+        rustup toolchain install nightly --allow-downgrade -c rustfmt
+        echo "$HOME/.cargo/bin" >> $GITHUB_PATH
+    - name: Check
+      run: |
+        ./codegen/codegen.sh
+        git diff --exit-code

codegen/codegen.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+
+set -ex
+
+cd "$(dirname "$BASH_SOURCE")/.."
+
+cargo run -p codegen
+cargo +nightly fmt