Improvements to formatting bot (#5421)

* Use github token for formatting command dispatch

* Open PR instead of committing directly when formatting

* Add --no-version-check option to formatting script

* Colorful diff output for cmake formatting

4 files changed, 100 insertions, 39 deletions

diff --git a/.github/actions/format-setup/action.yml b/.github/actions/format-setup/action.yml
new file mode 100644
index 000000000..58eddac77
--- /dev/null
+++ b/.github/actions/format-setup/action.yml
@@ -0,0 +1,21 @@
+name: Formatting tools setup
+
+description: Performs setup common to the code formatting actions
+
+runs:
+  using: composite
+  steps:
+    - name: install gersemi
+      shell: bash
+      run: |
+        pip3 install gersemi colorama
+
+    - name: install clang-format
+      shell: bash
+      run: |
+        tmpdir=$(mktemp -d)
+        curl -L -H "Authorization: token ${{github.token}}" \
+          -o "$tmpdir/clang-format" \
+          https://github.com/shader-slang/slang-binaries/raw/4e88845ec51641b4c92e68027e359090bdb219e0/clang-format/x86_64-linux/bin/clang-format
+        chmod +x "$tmpdir/clang-format"
+        echo "$tmpdir" >> $GITHUB_PATH
diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 4a68882ae..8a444f0ad 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -6,38 +6,74 @@ jobs:
   format:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - name: Checkout PR branch
+        uses: actions/checkout@v4
         with:
           token: ${{ secrets.SLANGBOT_PAT }}
           repository: ${{ github.event.client_payload.pull_request.head.repo.full_name }}
           ref: ${{ github.event.client_payload.pull_request.head.ref }}
+          path: pr-branch
 
-      - run: pip3 install gersemi
+      - name: Checkout target branch
+        uses: actions/checkout@v4
+        with:
+          token: ${{ secrets.SLANGBOT_PAT }}
+          repository: ${{ github.event.client_payload.pull_request.base.repo.full_name }}
+          ref: ${{ github.event.client_payload.pull_request.base.ref }}
+          path: target-branch
 
-      - name: install clang-format
-        run: |
-          tmpdir=$(mktemp -d)
-          curl -L -H "Authorization: token ${{ secrets.SLANGBOT_PAT }}" \
-            -o "$tmpdir/clang-format" \
-            https://github.com/shader-slang/slang-binaries/raw/4e88845ec51641b4c92e68027e359090bdb219e0/clang-format/x86_64-linux/bin/clang-format
-          chmod +x "$tmpdir/clang-format"
-          echo "$tmpdir" >> $GITHUB_PATH
+      - name: Setup
+        uses: ./target-branch/.github/actions/format-setup
 
-      - run: ./extras/formatting.sh
+      - name: Run formatting
+        id: format
+        run: |
+          ./target-branch/extras/formatting.sh --source ./pr-branch
 
       - name: Configure Git commit signing
+        id: git-info
         run: |
           echo "${{ secrets.SLANGBOT_SIGNING_KEY }}" > "${{runner.temp}}"/signing_key
           chmod 600 "${{runner.temp}}"/signing_key
-          git config commit.gpgsign true
-          git config gpg.format ssh
-          git config user.signingkey "${{runner.temp}}"/signing_key
+          git -C pr-branch config commit.gpgsign true
+          git -C pr-branch config gpg.format ssh
+          git -C pr-branch config user.signingkey "${{runner.temp}}"/signing_key
+          bot_info=$(curl -s -H "Authorization: Bearer ${{ secrets.SLANGBOT_PAT }}" \
+            "https://api.github.com/user")
+          echo "bot_identity=$(echo $bot_info | jq --raw-output '.login + " <" + (.id|tostring) + "+" + .login + "@users.noreply.github.com>"')" >> $GITHUB_OUTPUT
+          echo "bot_name=$(echo $bot_info | jq --raw-output '.login')" >> $GITHUB_OUTPUT
+
+      - name: Create Pull Request
+        id: create-pr
+        uses: peter-evans/create-pull-request@v7
+        with:
+          token: ${{ secrets.SLANGBOT_PAT }}
+          path: pr-branch
+          commit-message: "format code"
+          title: "Format code for PR #${{ github.event.client_payload.pull_request.number }}"
+          body: "Automated code formatting for ${{ github.event.client_payload.pull_request.url }}"
+          committer: ${{ steps.git-info.outputs.bot_identity }}
+          author: ${{ steps.git-info.outputs.bot_identity }}
+          branch: format-${{ github.event.client_payload.pull_request.number }}-${{ github.event.client_payload.pull_request.head.ref }}
+          base: ${{ github.event.client_payload.pull_request.head.ref }}
+          push-to-fork: ${{ steps.git-info.outputs.bot_name }}/slang
+          delete-branch: true
 
-      - uses: EndBug/add-and-commit@v9
+      - name: Comment on PR
+        uses: peter-evans/create-or-update-comment@v4
+        if: always()
         with:
-          fetch: false
-          message: "format code"
-          push: true
+          token: ${{ secrets.SLANGBOT_PAT }}
+          repository: ${{ github.event.client_payload.github.payload.repository.full_name }}
+          issue-number: ${{ github.event.client_payload.pull_request.number }}
+          body: |
+            ${{ 
+              steps.format.conclusion == 'failure'
+              && format('❌ Formatting failed. Please check the [workflow run](https://github.com/{0}/actions/runs/{1})', github.repository, github.run_id)
+              || (steps.create-pr.conclusion == 'failure' 
+                  && format('❌ Failed to create formatting pull request. Please check the [workflow run](https://github.com/{0}/actions/runs/{1})', github.repository, github.run_id)
+                  || format('🌈 Formatted, please merge the changes from [this PR]({0})', steps.create-pr.outputs.pull-request-url))
+            }}
 
       - name: Add reaction
         uses: peter-evans/create-or-update-comment@v4
diff --git a/.github/workflows/slash-command-dispatch.yml b/.github/workflows/slash-command-dispatch.yml
index c4c9a7ae7..2e72c3bf4 100644
--- a/.github/workflows/slash-command-dispatch.yml
+++ b/.github/workflows/slash-command-dispatch.yml
@@ -12,14 +12,9 @@ jobs:
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           reaction-token: ${{ secrets.SLANGBOT_PAT }}
-          config: >
-            [
-              {
-                "command": "format",
-                "permission": "none",
-                "issue_type": "pull-request"
-              }
-            ]
+          issue-type: pull-request
+          commands: | 
+            format
 
       - name: Edit comment with error message
         if: steps.scd.outputs.error-message
diff --git a/extras/formatting.sh b/extras/formatting.sh
index dc3bbc7ca..a53930eaf 100755
--- a/extras/formatting.sh
+++ b/extras/formatting.sh
@@ -2,15 +2,21 @@
 
 set -e
 
-SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"
-cd "$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel)" || exit 1
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"
+source_dir="$(dirname "$script_dir")"
 
 check_only=0
+no_version_check=0
 
 while [[ "$#" -gt 0 ]]; do
   case $1 in
   -h | --help) help=1 ;;
   --check-only) check_only=1 ;;
+  --no-version-check) no_version_check=1 ;;
+  --source)
+    source_dir="$2"
+    shift
+    ;;
   esac
   shift
 done
@@ -20,14 +26,18 @@ if [ "$help" ]; then
   cat <<EOF
 $me: Format or check formatting of files in this repo
 
-Usage: $me [--check-only]
+Usage: $me [--check-only] [--no-version-check] [--source <path>]
 
 Options:
-    --check-only     Check formatting without modifying files
+    --check-only       Check formatting without modifying files
+    --no-version-check Skip version compatibility checks
+    --source           Path to source directory to format (defaults to parent of script directory)
 EOF
   exit 0
 fi
 
+cd "$source_dir" || exit 1
+
 require_bin() {
   local name="$1"
   local required="$2"
@@ -39,19 +49,17 @@ require_bin() {
     return
   fi
 
-  version=$("$name" --version | grep -oP "$name(?:\s+version)?\s+\K\d+\.\d+\.?\d*")
-  if ! printf '%s\n%s\n' "$required" "$version" | sort -V -C; then
-    echo "$name version $version is too old. Version $required or newer is required."
-    missing_bin=1
+  if [ "$no_version_check" -eq 0 ]; then
+    version=$("$name" --version | grep -oP "$name(?:\s+version)?\s+\K\d+\.\d+\.?\d*")
+    if ! printf '%s\n%s\n' "$required" "$version" | sort -V -C; then
+      echo "$name version $version is too old. Version $required or newer is required."
+      missing_bin=1
+    fi
   fi
 }
 
 require_bin "git" "1.8"
-require_bin "gersemi" "0.16.2"
-
-if [ "${missing_bin:-}" = "1" ]; then
-  exit 1
-fi
+require_bin "gersemi" "0.17"
 
 if [ "$missing_bin" ]; then
   exit 1
@@ -79,3 +87,4 @@ cmake_formatting() {
 cmake_formatting
 
 exit $exit_code
+