CI: Streamline the autoformat process and format versions

After much iteration, this is the simplest solution I could come up with that fulfills all the requirements:

* A single clang-format version is used for all platforms
* The version can be pinned in one central location
* Whichever version is currently used will be tracked by git
* Doesn't consume resources excessively thanks to caching
* No reliance on third parties, other than the LLVM organization
* Uses the same script for both CI runs and local development
* No excessive branching/other accidental complexity
* Bonus: Approach can also be used to install clang-tidy (later)

Downloading a huge release tarball just for the tiny formatter feels like overkill, but none of the other solutions I explored were a net gain.

.github/autoformat.env

@@ -0,0 +1,2 @@
+EVO_CLANGFORMAT_VERSION=19.1.2
+EVO_STYLUA_VERSION=v0.20.0

.github/workflows/autoformat.yml

@@ -19,41 +19,66 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
+        include:
+          - os: ubuntu-latest
+            stylua: stylua-linux.zip
+            exe: ""
+          - os: macos-latest
+            stylua: stylua-macos.zip
+            exe: ""
+          - os: windows-latest
+            stylua: stylua-win64.zip
+            exe: ".exe"
+    defaults:
+      run:
+        shell: bash
 
     steps:
-      # MSYS needs to be available before running any git commands
-      - name: Install clang-format (via MSYS)
-        if: runner.os == 'Windows'
-        uses: msys2/setup-msys2@v2
-        with:
-          install: git mingw-w64-x86_64-clang
-
       - name: Disable autocrlf # Messes up everything on Windows since the formatter applies \n
         run: |
           git config --global core.autocrlf false
           git config --global core.eol lf
 
       - name: Check out Git repository
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+          submodules: false
+
+      - name: Set up environment
+        run: |
+          set -a
+          source .github/autoformat.env
+          cat .github/autoformat.env >> $GITHUB_ENV
+          echo $(pwd) >> $GITHUB_PATH
 
-      - name: Set up StyLua
-        uses: JohnnyMorganz/[email protected]
+      - name: Cache clang-format binary
+        id: cache-clang-format
+        uses: actions/cache@v4
         with:
-          token: ${{ secrets.GITHUB_TOKEN }}
-          args: --check . --verbose
-          version: v0.20.0
-
-        # The preinstalled version is positively antique; replace with the latest and greatest (to match MSYS)
-      - name: Install clang-format (via APT)
-        if: runner.os == 'Linux'
-        run: ./deps/install-clang-format.sh
-
-      - name: Install clang-format (via Homebrew)
-        if: runner.os == 'macOS'
-        run: brew install clang-format
-
+          path: clang-format${{ matrix.exe }}
+          key: clang-format-${{ runner.os }}-${{ env.EVO_CLANGFORMAT_VERSION }}
+          restore-keys: |
+            clang-format-${{ runner.os }}-${{ env.EVO_CLANGFORMAT_VERSION }}
+
+      - name: Install clang-format
+        if: steps.cache-clang-format.outputs.cache-hit != 'true'
+        run: deps/get-clang-format.sh
+
+      - name: Verify clang-format version
+        run: which clang-format && clang-format --version
+
+      - name: Install stylua
+        run: |
+          curl --location --output ${{ matrix.stylua }} https://github.com/JohnnyMorganz/StyLua/releases/download/${{ env.EVO_STYLUA_VERSION }}/${{ matrix.stylua }}
+          unzip ${{ matrix.stylua }}
+          chmod +x stylua
+
+      - name: Verify stylua version
+        run: which stylua && stylua --version
+
       - name: Run autoformat
         run: ./autoformat.sh
 
       - name: Check for inconsistent formatting
-        run: git --no-pager diff --exit-code -b . #The -b is for inconsistent newlines, which we ignore (for now)
+        run: git --no-pager diff --exit-code -b .

autoformat.sh

@@ -1,20 +1,15 @@
-# See deps/install-clang-format.sh for the required version (should always match)
-REQUIRED_CLANG_FORMAT_VERSION="17"
-CLANG_FORMAT="clang-format-$REQUIRED_CLANG_FORMAT_VERSION"
-
-# The MSYS version may lag behind somewhat, so a fallback option is needed
-if ! command -v $CLANG_FORMAT &> /dev/null
-then
-    echo "clang-format-$REQUIRED_CLANG_FORMAT_VERSION not found. Using the default clang-format instead"
-	echo
-    CLANG_FORMAT="clang-format"
-fi
+#!/bin/bash
+set -aeuo pipefail
 
+STYLUA="stylua"
+CLANG_FORMAT="clang-format"
 echo "Installed formatters:"
 echo
 
-echo "* " $(stylua --version)
-echo "* " $($CLANG_FORMAT --version)
+echo $(which $STYLUA)
+echo $($STYLUA --version)
+echo $(which $CLANG_FORMAT)
+echo $($CLANG_FORMAT --version)
 echo
 
 echo "Formatting Lua sources ..."

deps/get-clang-format.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+set -aeuo pipefail
+source .github/autoformat.env
+
+GITHUB_ORGANIZATION="llvm"
+GITHUB_REPOSITORY="llvm-project"
+REQUIRED_LLVM_VERSION=$EVO_CLANGFORMAT_VERSION # Pinned via ENV file to avoid headaches in CI runs
+LLVMORG_SUFFIX="llvmorg-$REQUIRED_LLVM_VERSION"
+GITHUB_BASE_URL="https://github.com/$GITHUB_ORGANIZATION/$GITHUB_REPOSITORY/releases/download/$LLVMORG_SUFFIX"
+
+echo "Downloading clang-format release for version $REQUIRED_LLVM_VERSION"
+
+PLATFORM=$(uname)
+echo "Detected platform: $PLATFORM"
+
+case $PLATFORM in
+    MINGW64_NT*|CYGWIN_NT*|MSYS_NT*)
+        LLVM_ASSET_NAME="LLVM-$REQUIRED_LLVM_VERSION-Windows-X64"
+        CLANG_FORMAT_EXECUTABLE="clang-format.exe"
+        ;;
+    Linux)
+        LLVM_ASSET_NAME="LLVM-$REQUIRED_LLVM_VERSION-Linux-X64"
+        CLANG_FORMAT_EXECUTABLE="clang-format"
+        ;;
+    Darwin)
+        LLVM_ASSET_NAME="LLVM-$REQUIRED_LLVM_VERSION-macOS-ARM64"
+        CLANG_FORMAT_EXECUTABLE="clang-format"
+        ;;
+    *)
+        echo "Unsupported platform: $PLATFORM"
+        exit 1
+        ;;
+esac
+
+LLVM_RELEASE_ASSET="$LLVM_ASSET_NAME.tar.xz"
+TARBALL_DOWNLOAD_DIR=$(pwd)/deps
+TARBALL_DOWNLOAD_FILE="$TARBALL_DOWNLOAD_DIR/$LLVM_RELEASE_ASSET"
+
+LLVM_RELEASE_URL="$GITHUB_BASE_URL/$LLVM_RELEASE_ASSET"
+echo "Fetching $LLVM_RELEASE_URL ..."
+curl --location --output "$TARBALL_DOWNLOAD_FILE" "$LLVM_RELEASE_URL"
+
+CLANG_FORMAT_PATH="$LLVM_ASSET_NAME/bin/$CLANG_FORMAT_EXECUTABLE"
+echo "Unpacking $CLANG_FORMAT_PATH ..."
+tar --strip-components=2 -xvf "$TARBALL_DOWNLOAD_FILE" "$CLANG_FORMAT_PATH"
+
+chmod +x "./$CLANG_FORMAT_EXECUTABLE"
+
+echo "Cleanup: Removing $TARBALL_DOWNLOAD_FILE ..."
+rm $TARBALL_DOWNLOAD_FILE