CI/c-f check: adapt jidicula script

.github/workflows/ci.yaml

@@ -46,12 +46,38 @@ jobs:
     if: github.event_name != 'pull_request' || github.event.pull_request.head.repo.fork
     name: "Code Style"
     runs-on: ubuntu-latest
+    container:
+      image: archlinux
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      # - name: clang-format check
+      #   uses: jidicula/clang-format-action@v4.16.0
+      #   with:
+      #     exclude-regex: ^subprojects$
+
+      - name: Install clang-format
+        run: |
+          pacman --noconfirm --noprogressbar -Syyu
+          pacman --noconfirm --noprogressbar -Sy clang
+
       - name: clang-format check
-        uses: jidicula/clang-format-action@v4.16.0
-        with:
-          clang-format-version: 20
-          exclude-regex: ^subprojects$
+        run: .github/workflows/clang-format-check.sh "." "llvm" "^subprojects$" ""
+
+      - name: Save PR head commit SHA
+        if: failure() && github.event_name == 'pull_request'
+        shell: bash
+        run: |
+          SHA="${{ github.event.pull_request.head.sha }}"
+          echo "SHA=$SHA" >> $GITHUB_ENV
+      - name: Save latest commit SHA if not PR
+        if: failure() && github.event_name != 'pull_request'
+        shell: bash
+        run: echo "SHA=${{ github.sha }}" >> $GITHUB_ENV
+
+      - name: Report failure in job summary
+        if: failure()
+        run: |
+          DEEPLINK="${{ github.server_url }}/${{ github.repository }}/commit/${{ env.SHA }}"
+          echo -e "Format check failed on commit [${GITHUB_SHA:0:8}]($DEEPLINK) with files:\n$(<$GITHUB_WORKSPACE/failing-files.txt)" >> $GITHUB_STEP_SUMMARY

.github/workflows/clang-format-check.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+#
+# Adapted from https://github.com/jidicula/clang-format-action
+
+###############################################################################
+#                                check.sh                                     #
+###############################################################################
+# USAGE: ./entrypoint.sh [<path>] [<fallback style>]
+#
+# Checks all C/C++/Protobuf/CUDA files (.h, .H, .hpp, .hh, .h++, .hxx and .c,
+# .C, .cpp, .cc, .c++, .cxx, .proto, .cu) in the provided GitHub repository path
+# (arg1) for conforming to clang-format. If no path is provided or provided path
+# is not a directory, all C/C++/Protobuf/CUDA files are checked. If any files
+# are incorrectly formatted, the script lists them and exits with 1.
+#
+# Define your own formatting rules in a .clang-format file at your repository
+# root. Otherwise, the provided style guide (arg2) is used as a fallback.
+
+# format_diff function
+# Accepts a filepath argument. The filepath passed to this function must point
+# to a C/C++/Protobuf/CUDA file.
+format_diff() {
+  local filepath="$1"
+
+  # Invoke clang-format with dry run and formatting error output
+  local_format="$(clang-format \
+    --dry-run \
+    --Werror \
+    --style=file \
+    --fallback-style="$FALLBACK_STYLE" \
+    "${filepath}")"
+
+  local format_status="$?"
+  if [[ ${format_status} -ne 0 ]]; then
+    # Append Markdown-bulleted monospaced filepath of failing file to
+    # summary file.
+    echo "* \`$filepath\`" >>failing-files.txt
+
+    echo "Failed on file: $filepath" >&2
+    echo "$local_format" >&2
+    exit_code=1 # flip the global exit code
+    return "${format_status}"
+  fi
+  return 0
+}
+
+CHECK_PATH="$1"
+FALLBACK_STYLE="$2"
+EXCLUDE_REGEX="$3"
+INCLUDE_REGEX="$4"
+
+# Set the regex to an empty string regex if nothing was provided
+if [[ -z $EXCLUDE_REGEX ]]; then
+  EXCLUDE_REGEX="^$"
+fi
+
+# Set the filetype regex if nothing was provided.
+# Find all C/C++/Protobuf/CUDA files:
+#   h, H, hpp, hh, h++, hxx
+#   c, C, cpp, cc, c++, cxx
+#   ino, pde
+#   proto
+#   cu
+if [[ -z $INCLUDE_REGEX ]]; then
+  INCLUDE_REGEX='^.*\.((((c|C)(c|pp|xx|\+\+)?$)|((h|H)h?(pp|xx|\+\+)?$))|(ino|pde|proto|cu))$'
+fi
+
+cd "$GITHUB_WORKSPACE" || exit 2
+
+if [[ ! -d $CHECK_PATH ]]; then
+  echo "Not a directory in the workspace, fallback to all files." >&2
+  CHECK_PATH="."
+fi
+
+# initialize exit code
+exit_code=0
+
+# All files improperly formatted will be printed to the output.
+src_files=$(find "$CHECK_PATH" -name .git -prune -o -regextype posix-egrep -regex "$INCLUDE_REGEX" -print)
+
+# check formatting in each source file
+IFS=$'\n' # Loop below should separate on new lines, not spaces.
+for file in $src_files; do
+  # Only check formatting if the path doesn't match the regex
+  if ! [[ ${file} =~ $EXCLUDE_REGEX ]]; then
+    format_diff "${file}"
+  fi
+done
+
+# global exit code is flipped to nonzero if any invocation of `format_diff` has
+# a formatting difference.
+exit "$exit_code"