build: add clang-tidy

.clang-tidy

@@ -0,0 +1,44 @@
+---
+# Broad families, minus the checks that fight the domain rather than help it.
+# Each exclusion is deliberate:
+#
+#   bugprone-branch-clone                  false positive on `if constexpr`
+#   bugprone-easily-swappable-parameters   h(i, j), check_equal_size(a, b)
+#   bugprone-throwing-static-init*         only fires on the test fixtures,
+#                                          the header itself has no globals
+#   misc-include-cleaner                   noisy for a single umbrella header
+#   modernize-use-nodiscard                57 sites; annotating the API with
+#                                          [[nodiscard]] is a decision to make
+#                                          on purpose, not a lint fix
+#   modernize-use-trailing-return-type     style the project does not use
+#   portability-avoid-pragma-once          #pragma once is a deliberate choice
+#   readability-function-cognitive-*       binary()/ternary() are inherently so
+#   readability-identifier-length          i, j, f, g, da, daa are the notation
+#   readability-magic-numbers              the constants are the formulas
+#   readability-math-missing-parentheses   precedence is the notation as well
+#   readability-named-parameter            unused parameters in tag types
+Checks: >
+  bugprone-*,
+  clang-analyzer-*,
+  misc-*,
+  modernize-*,
+  performance-*,
+  portability-*,
+  readability-*,
+  -bugprone-branch-clone,
+  -bugprone-easily-swappable-parameters,
+  -bugprone-throwing-static-initialization,
+  -misc-include-cleaner,
+  -modernize-use-nodiscard,
+  -modernize-use-trailing-return-type,
+  -portability-avoid-pragma-once,
+  -readability-function-cognitive-complexity,
+  -readability-identifier-length,
+  -readability-magic-numbers,
+  -readability-math-missing-parentheses,
+  -readability-named-parameter
+
+# Only our own headers. Eigen, doctest and pybind11 are not ours to fix.
+HeaderFilterRegex: 'include/hyperjet/.*\.h$'
+
+FormatStyle: file

justfile

@@ -0,0 +1,31 @@
+# Format all C++ sources in place
+format:
+  uv run --only-group dev clang-format -i include/hyperjet/*.h python/src/*.h python/src/*.cpp test/src/*.cpp benchmark/src/*.cpp
+
+# Generate the compilation database that clang-tidy needs
+compile-db:
+  #!/usr/bin/env bash
+  set -euo pipefail
+  # The test build is the right entry point: it instantiates the templates, and
+  # an uninstantiated template is never analysed.
+  args=(-Stest -Bbuild/tidy -DCMAKE_BUILD_TYPE=Debug
+        -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+        -DCMAKE_POLICY_VERSION_MINIMUM=3.5)
+  # AppleClang knows the macOS SDK implicitly, the standalone clang-tidy does
+  # not, so the sysroot has to end up in the compilation database.
+  if [ "$(uname)" = Darwin ]; then
+    args+=("-DCMAKE_OSX_SYSROOT=$(xcrun --show-sdk-path)")
+  fi
+  cmake "${args[@]}" > /dev/null
+
+# One invocation for all units rather than run-clang-tidy.py: with only two of
+# them the parallel driver is no faster, and it reports every finding in the
+# header once per unit instead of once.
+
+# Run clang-tidy over the test translation units
+tidy: compile-db
+  uv run --only-group tidy clang-tidy -p build/tidy --quiet test/src/*.cpp
+
+# Same, applying the fixes clang-tidy can make itself
+tidy-fix: compile-db
+  uv run --only-group tidy clang-tidy -p build/tidy --quiet --fix test/src/*.cpp

pyproject.toml

@@ -33,6 +33,9 @@ Repository = "https://github.com/oberbichler/HyperJet"
 
 [dependency-groups]
 dev = ["clang-format>=19.0", "ruff>=0.11"]
+# Separate group: the clang-tidy wheel is ~44 MB against ~2 MB for
+# clang-format, and the format CI job has no use for it.
+tidy = ["clang-tidy>=19.0"]
 test = ["pytest>=8.0"]
 
 [tool.scikit-build]