Add a clang-format and format the code accordingly

This is fairly close to what we have and at least enforces a consistent
coding style. The only true change in style is no indentation for case
in switch statements, the rest is a combination of styles we already
used in one place or another, just not consistently.

Author: whot

.clang-format

@@ -0,0 +1,53 @@
+AlignAfterOpenBracket: Align
+# This option we want but it's frequently broken and causes bad
+# misalignment. The canary is wheel_click_count_parser, if that works
+# we can actually enable it.
+# AlignArrayOfStructures: Left
+AlignConsecutiveShortCaseStatements:
+  Enabled: true
+  AcrossEmptyLines: false
+  AcrossComments: true
+  AlignCaseColons: false
+AllowAllParametersOfDeclarationOnNextLine: false
+AllowAllArgumentsOnNextLine: false
+BinPackArguments: false
+BinPackParameters: AlwaysOnePerLine
+BraceWrapping:
+  AfterFunction: true
+BreakAfterReturnType: All
+BreakBeforeBraces: Custom
+BreakStringLiterals: false
+ColumnLimit: 88
+ContinuationIndentWidth: 8
+Cpp11BracedListStyle: false
+IncludeBlocks: Regroup
+IncludeCategories:
+  - Regex:           '^(<|")config\.h(>|")'
+    Priority:        0
+    SortPriority:    0
+  - Regex:           '^<.*'
+    Priority:        1
+    SortPriority:    0
+  - Regex:           '^"util-.*'
+    Priority:        2
+    SortPriority:    0
+  - Regex:           '.*'
+    Priority:        3
+    SortPriority:    0
+IndentCaseLabels: false
+IndentWidth: 8
+PointerAlignment: Right
+RemoveEmptyLinesInUnwrappedLines: true
+RemoveParentheses: MultipleParentheses
+RemoveSemicolon: true
+SkipMacroDefinitionBody: true
+SortIncludes: true
+SpaceAfterCStyleCast: false
+SpaceAfterLogicalNot: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeCaseColon: false
+SpaceBeforeParens: ControlStatementsExceptControlMacros
+SpacesInContainerLiterals: true
+SpacesInParens: Custom
+TabWidth: 8
+UseTab: ForContinuationAndIndentation

.clang-format-ignore

@@ -0,0 +1 @@
+include/**/*

.github/workflows/style.yml

@@ -0,0 +1,26 @@
+name: "Coding style"
+
+on: [ push, pull_request ]
+
+permissions:
+  contents: read
+
+# see https://github.com/ssciwr/clang-format-wheel
+env:
+  PIP_PACKAGES: clang-format
+
+jobs:
+  clang-format:
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.12'
+      - uses: ./.github/actions/pkginstall
+        with:
+          pip: $PIP_PACKAGES
+      - run: clang-format -i -- **/*.c **/*.h
+      - run: git diff --exit-code
+      - if: failure()
+        run: echo "Please run clang-format (or via pre-commit) against the modified sources"

.pre-commit-config.yaml

@@ -12,3 +12,8 @@ repos:
   - id: ruff
     args: ['--ignore=E741,E501']
   - id: ruff-format
+- repo: https://github.com/pre-commit/mirrors-clang-format
+  rev: v20.1.6
+  hooks:
+  - id: clang-format
+    types_or: [c]