CI: Add a job that runs clang-format on PR changes

.clang-format

@@ -0,0 +1,148 @@
+---
+Language: Cpp
+BasedOnStyle: LLVM
+AccessModifierOffset: -2
+AlignAfterOpenBracket: Align
+AlignConsecutiveMacros: true
+AlignConsecutiveAssignments: false
+AlignConsecutiveBitFields: true
+AlignConsecutiveDeclarations: true
+AlignEscapedNewlines: Left
+AlignTrailingComments: true
+AllowAllArgumentsOnNextLine: false
+AllowAllConstructorInitializersOnNextLine: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowShortEnumsOnASingleLine: true
+AllowShortBlocksOnASingleLine: Never
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: All
+AllowShortLambdasOnASingleLine: All
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: TopLevelDefinitions
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: MultiLine
+BinPackArguments: true
+BinPackParameters: false
+BraceWrapping:
+  AfterCaseLabel: false
+  AfterClass: false
+  AfterControlStatement: Never
+  AfterEnum: false
+  AfterFunction: false
+  AfterNamespace: false
+  AfterObjCDeclaration: false
+  AfterStruct: false
+  AfterUnion: false
+  AfterExternBlock: false
+  BeforeCatch: false
+  BeforeElse: false
+  BeforeLambdaBody: false
+  BeforeWhile: false
+  IndentBraces: false
+  SplitEmptyFunction: true
+  SplitEmptyRecord: true
+  SplitEmptyNamespace: true
+BreakBeforeBinaryOperators: None
+BreakBeforeBraces: WebKit
+BreakBeforeInheritanceComma: false
+BreakInheritanceList: BeforeColon
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+BreakConstructorInitializers: BeforeColon
+BreakAfterJavaFieldAnnotations: false
+BreakStringLiterals: true
+ColumnLimit: 120
+CommentPragmas: '^ IWYU pragma:'
+CompactNamespaces: false
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DeriveLineEnding: true
+DerivePointerAlignment: false
+DisableFormat: false
+ExperimentalAutoDetectBinPacking: true
+FixNamespaceComments: true
+ForEachMacros:
+  - wl_list_for_each
+  - wl_list_for_each_safe
+IncludeBlocks: Preserve
+IncludeCategories:
+  - Regex: '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority: 2
+    SortPriority: 0
+  - Regex: '^(<|"(gtest|gmock|isl|json)/)'
+    Priority: 3
+    SortPriority: 0
+  - Regex: '.*'
+    Priority: 1
+    SortPriority: 0
+IncludeIsMainRegex: '(Test)?$'
+IncludeIsMainSourceRegex: ''
+IndentCaseLabels: false
+IndentCaseBlocks: false
+IndentGotoLabels: true
+IndentPPDirectives: None
+IndentExternBlock: AfterExternBlock
+IndentWidth: 4
+IndentWrappedFunctionNames: false
+InsertTrailingCommas: None
+JavaScriptQuotes: Double
+JavaScriptWrapImports: true
+KeepEmptyLinesAtTheStartOfBlocks: true
+MacroBlockBegin: ''
+MacroBlockEnd: ''
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBinPackProtocolList: Auto
+ObjCBlockIndentWidth: 2
+ObjCBreakBeforeNestedBlockParam: true
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PenaltyBreakAssignment: 2
+PenaltyBreakBeforeFirstCallParameter: 19
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyBreakTemplateDeclaration: 10
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 60
+PointerAlignment: Left
+ReflowComments: false
+SortIncludes: true
+SortUsingDeclarations: true
+SpaceAfterCStyleCast: true
+SpaceAfterLogicalNot: false
+SpaceAfterTemplateKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCpp11BracedList: false
+SpaceBeforeCtorInitializerColon: true
+SpaceBeforeInheritanceColon: true
+SpaceBeforeParens: ControlStatementsExceptForEachMacros
+SpaceBeforeRangeBasedForLoopColon: true
+SpaceInEmptyBlock: false
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles: false
+SpacesInConditionalStatement: false
+SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+SpaceBeforeSquareBrackets: false
+Standard: Latest
+StatementMacros:
+  - Q_UNUSED
+  - QT_REQUIRE_VERSION
+TabWidth: 4
+UseCRLF: false
+UseTab: Never
+WhitespaceSensitiveMacros:
+  - STRINGIZE
+  - PP_STRINGIZE
+TypenameMacros:
+  - g_auto
+  - g_autoptr
+...

.github/workflows/codestyle.yml

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+---
+name: Code Style
+on: [pull_request]
+
+jobs:
+  check:
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Checkout Head
+        uses: actions/checkout@v2
+      - name: Fetch Git History
+        run: |
+          git fetch --no-tags --prune --depth=1 \
+            origin +refs/heads/master:refs/remotes/origin/master
+      - name: Install Tools
+        run: |
+          curl -sL https://apt.llvm.org/llvm-snapshot.gpg.key | \
+            sudo apt-key add -
+          sudo add-apt-repository \
+            'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-13 main'
+          sudo apt update
+          sudo apt install -y clang-format-13 diffutils
+      - name: Check
+        run: |
+          scripts/check-style -ocode-style.diff origin/master
+      - name: Archive Diff
+        uses: actions/upload-artifact@v2
+        if: failure()
+        with:
+          name: diff
+          path: code-style.diff

scripts/check-style

@@ -0,0 +1,131 @@
+#! /usr/bin/env bash
+set -eu -o pipefail
+
+FILE=
+BASE=
+HEAD=HEAD
+
+declare -a args=()
+diff_input=false
+show_help=false
+
+for opt in "$@" ; do
+    case "${opt}" in
+        -h | --help)
+            show_help=true
+            ;;
+        -d | --diff)
+            diff_input=true
+            ;;
+        -o*)
+            FILE=${opt#-o}
+            ;;
+        *)
+            args+=("${opt}")
+            ;;
+    esac
+done
+declare -r diff_input show_help
+
+show_help ()
+{
+    echo "Usage: $0 [-o<file>] [-d|--diff] [<committish> [<committish>]]"
+}
+
+if ${show_help} ; then
+    show_help
+    exit
+fi
+
+if [[ ${#args[@]} -eq 1 ]] ; then
+    BASE=${args[0]}
+elif [[ ${#args[@]} -eq 2 ]] ; then
+    BASE=${args[0]}
+    HEAD=${args[1]}
+elif [[ ${#args[@]} -eq 0 ]] && ${diff_input} ; then
+    : no-op
+else
+    show_help 1>&2
+    exit 1
+fi
+declare -r BASE HEAD
+
+declare -ra clang_format_diff_candidates=(
+    # Search in $PATH (Ubuntu, Debian, maybe others)
+    clang-format-diff-13
+    clang-format-diff-13.py
+    clang-format-diff
+    clang-format-diff.py
+    # Arch Linux, Fedora.
+    /usr/share/clang/clang-format-diff.py
+)
+
+find_program ()
+{
+    local candidate path
+    for candidate in "$@" ; do
+        path=$(type -P "${candidate}")
+        if [[ -x ${path} ]] ; then
+            echo "${path}"
+            return
+        fi
+    done
+
+    # Not found.
+    return 1
+}
+
+clang_format_diff=$(find_program "${clang_format_diff_candidates[@]}")
+clang_format=$(find_program clang-format-11 clang-format)
+declare -r clang_format_diff clang_format
+
+if [[ ! -x ${clang_format_diff} ]] ; then
+    echo "$0: clang-format-diff does not seem to be installed" 1>&2
+    exit 1
+fi
+
+if [[ ! -x ${clang_format} ]] ; then
+    echo "$0: clang-format does not seem to be installed" 1>&2
+    exit 1
+fi
+
+#
+# Check the version of clang-format, to make sure that it will support the
+# configuration file. The output of "clang-format --version" is formatted
+# as follows:
+#
+#   clang-format version X.Y.Z
+#
+declare -r clang_format_min_version=11
+
+clang_format_version=$("${clang_format}" --version)
+if [[ ${clang_format_version} =~ clang-format[[:space:]]+version[[:space:]]+([[:digit:]]+)\. ]] ; then
+    clang_format_version=${BASH_REMATCH[1]}
+    if [[ ${clang_format_version} -lt ${clang_format_min_version} ]] ; then
+        echo "$0: clang-format ${clang_format_min_version}+ is needed, ${clang_format_version} detected" 1>&2
+        exit 1
+    fi
+else
+    echo "$0: clang-format did not report its version number"
+    exit 1
+fi
+
+if [[ -z ${FILE} ]] ; then
+    FILE=$(mktemp)
+    trap 'rm -f "${FILE}"' EXIT
+else
+    trap '[[ -s ${FILE} ]] || rm -f "${FILE}"' EXIT
+fi
+
+declare -a input_cmd
+if ${diff_input} ; then
+    input_cmd=(cat)
+else
+    input_cmd=(git diff --no-color -U0 "${BASE}" "${HEAD}")
+fi
+
+"${input_cmd[@]}" \
+    | "${clang_format_diff}" -p1 -style=file -regex='.+\.(c|h)' \
+    | tee "${FILE}"
+
+[[ ! -s ${FILE} ]]