Enable clang-tidy tooling

.clang-tidy

@@ -0,0 +1,36 @@
+# Shared clang-tidy baseline for dd-trace-cpp, httpd-datadog, and nginx-datadog.
+# Keep this file in sync across those repositories.
+Checks: >
+  -*,
+  bugprone-assert-side-effect,
+  bugprone-bool-pointer-implicit-conversion,
+  bugprone-copy-constructor-init,
+  bugprone-dangling-handle,
+  bugprone-forwarding-reference-overload,
+  bugprone-inaccurate-erase,
+  bugprone-infinite-loop,
+  bugprone-macro-repeated-side-effects,
+  bugprone-move-forwarding-reference,
+  bugprone-parent-virtual-call,
+  bugprone-posix-return,
+  bugprone-string-constructor,
+  bugprone-undelegated-constructor,
+  bugprone-unused-raii,
+  bugprone-virtual-near-miss,
+  misc-unused-using-decls,
+  readability-delete-null-pointer,
+  readability-redundant-control-flow,
+  readability-redundant-string-cstr
+# Deferred until existing findings are cleaned up:
+# bugprone-argument-comment
+# bugprone-use-after-move
+# misc-redundant-expression
+# misc-static-assert
+# modernize-redundant-void-arg
+# performance-move-const-arg
+# performance-noexcept-move-constructor
+# readability-redundant-member-init
+# readability-simplify-boolean-expr
+WarningsAsErrors: '*'
+HeaderFilterRegex: '^src/'
+FormatStyle: file

.github/workflows/dev.yml

@@ -18,6 +18,8 @@ jobs:
         run: bin/check-environment-variables
       - name: Configure
         run: bin/with-toolchain llvm cmake . -B ${BUILD_DIR} --preset ci-clang
+      - name: clang-tidy
+        run: bin/check-tidy
       - name: Build
         run: cmake --build ${BUILD_DIR} -j --target config-inversion -v
       - name: Verify supported configurations metadata

.gitignore

@@ -1,4 +1,5 @@
 .build/
+.clang-tidy-build/
 .cache/
 .coverage/
 .cursor/

CMakeLists.txt

@@ -48,6 +48,8 @@ if(CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
   option(DD_TRACE_BUILD_BENCHMARK "Build benchmark binaries" OFF)
   option(DD_TRACE_ENABLE_COVERAGE "Build code with code coverage profiling instrumentation" OFF)
   option(DD_TRACE_ENABLE_SANITIZE "Build with address sanitizer and undefined behavior sanitizer" OFF)
+  option(DD_TRACE_ENABLE_CLANG_TIDY "Run clang-tidy on first-party sources during build" OFF)
+  set(DD_TRACE_CLANG_TIDY "clang-tidy-14" CACHE STRING "clang-tidy executable when DD_TRACE_ENABLE_CLANG_TIDY is ON")
 endif()
 
 # Include mandatory files
@@ -258,6 +260,11 @@ set_target_properties(dd-trace-cpp-objects
     POSITION_INDEPENDENT_CODE ${BUILD_SHARED_LIBS}
 )
 
+if(DD_TRACE_ENABLE_CLANG_TIDY)
+  set_property(TARGET dd-trace-cpp-objects PROPERTY CXX_CLANG_TIDY
+    "${DD_TRACE_CLANG_TIDY};--quiet;--use-color")
+endif()
+
 install(
   TARGETS dd-trace-cpp-objects dd-trace-cpp-specs
   EXPORT dd-trace-cpp-targets

CMakePresets.json

@@ -39,6 +39,7 @@
       "displayName": "CI Clang",
       "cacheVariables": {
         "CMAKE_BUILD_TYPE": "Debug",
+        "CMAKE_EXPORT_COMPILE_COMMANDS": "ON",
         "DD_TRACE_ENABLE_SANITIZE": "ON",
         "DD_TRACE_BUILD_TOOLS": "ON",
         "DD_TRACE_BUILD_TESTING": "ON"

Dockerfile

@@ -18,7 +18,7 @@ run apt-get update && apt-get install --yes software-properties-common && \
     add-apt-repository ppa:git-core/ppa --yes && \
     apt-get update && apt-get upgrade --yes && \
     apt-get install --yes \
-        wget build-essential clang sed gdb clang-format git ssh shellcheck \
+        wget build-essential clang sed gdb clang-format clang-tidy git ssh shellcheck \
         libc++-dev libc++abi-dev python3 pip coreutils curl gnupg nodejs
 
 # bazelisk, a launcher for bazel. `bazelisk --help` will cause the latest

bin/README.md

@@ -11,6 +11,9 @@ This directory contains scripts that are useful during development.
   before pushing changes.
 - [check-format](check-format) verifies that the source code is formatted as
   [format](format) prefers.
+- [check-tidy](check-tidy) runs **clang-tidy-14** (pinned, same major as the
+  CI Clang) through CMake's `CXX_CLANG_TIDY` on `dd-trace-cpp-objects`. Do
+  not point it at a host `compile_commands.json`.
 - [check-version](check-version) accepts a version string as a command line
   argument (e.g. "v1.2.3") and checks whether the version within the source code
   matches. This is a good check to perform before publishing a source release.

bin/check-tidy

@@ -0,0 +1,95 @@
+#!/bin/sh
+# Run the pinned clang-tidy through CMake in the CI container.
+#
+# clang-tidy must use the same compiler, flags, and stdlib as the real
+# build (ci-clang + libc++). CMake's CXX_CLANG_TIDY on
+# dd-trace-cpp-objects does that: it invokes tidy with the exact compile
+# line after `--`. Do not run tidy against a host compilation database.
+#
+# Usage: bin/check-tidy
+
+set -e
+
+SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
+REPO_ROOT=$(cd "$SCRIPT_DIR/.." && pwd)
+cd "$REPO_ROOT"
+
+# Keep this in sync with .github/workflows/dev.yml and cmake/compiler/clang.cmake.
+CLANG_TIDY_VERSION=14
+CI_IMAGE_BASE=datadog/docker-library:dd-trace-cpp-ci-23768e9
+
+in_container() {
+    [ -f /.dockerenv ] || [ -n "${KUBERNETES_SERVICE_HOST:-}" ] || \
+        [ "${DD_TRACE_CPP_TIDY_IN_CONTAINER:-}" = "1" ]
+}
+
+docker_arch() {
+    case "$(uname -m)" in
+        arm64|aarch64) echo arm64 ;;
+        *) echo amd64 ;;
+    esac
+}
+
+if ! in_container; then
+    if ! command -v docker >/dev/null 2>&1; then
+        >&2 echo "docker is required to run clang-tidy-$CLANG_TIDY_VERSION."
+        exit 1
+    fi
+    if ! docker info >/dev/null 2>&1; then
+        >&2 echo "Docker is not running. Please start Docker."
+        exit 1
+    fi
+    arch=$(docker_arch)
+    image="${CI_IMAGE_BASE}-${arch}"
+    exec docker run --rm -t \
+        --platform "linux/${arch}" \
+        -e DD_TRACE_CPP_TIDY_IN_CONTAINER=1 \
+        -e BUILD_DIR=.clang-tidy-build \
+        -v "$REPO_ROOT:$REPO_ROOT" \
+        -w "$REPO_ROOT" \
+        "$image" \
+        bin/check-tidy
+fi
+
+build_dir=${BUILD_DIR:-.clang-tidy-build}
+tidy=clang-tidy-$CLANG_TIDY_VERSION
+
+if ! command -v "$tidy" >/dev/null 2>&1; then
+    if [ -f /etc/debian_version ]; then
+        apt-get update
+        DEBIAN_FRONTEND=noninteractive apt-get install --yes "$tidy"
+    else
+        >&2 echo "$tidy is required (pinned). Install it in this container."
+        exit 1
+    fi
+fi
+
+if ! command -v "$tidy" >/dev/null 2>&1; then
+    >&2 echo "$tidy is not installed."
+    exit 1
+fi
+
+compiler=${CXX:-clang++}
+if ! command -v "$compiler" >/dev/null 2>&1; then
+    >&2 echo "$compiler is required (same toolchain as CMake)."
+    exit 1
+fi
+
+compiler_major=$("$compiler" -dumpversion | cut -d. -f1)
+tidy_major=$("$tidy" --version | sed -n 's/.*version \([0-9][0-9]*\).*/\1/p' | head -n 1)
+if [ "$compiler_major" != "$CLANG_TIDY_VERSION" ] || [ "$tidy_major" != "$CLANG_TIDY_VERSION" ]; then
+    >&2 echo "clang-tidy and the CMake compiler must both be LLVM $CLANG_TIDY_VERSION."
+    >&2 echo "  $compiler: $compiler_major"
+    >&2 echo "  $tidy: $tidy_major"
+    exit 1
+fi
+
+# Reconfigure so CXX_CLANG_TIDY is attached to dd-trace-cpp-objects, then
+# compile that target. CMake passes the exact ci-clang compile line
+# (including -stdlib=libc++) to tidy. First-party src/ only; no extra-args.
+bin/with-toolchain llvm cmake . -B "$build_dir" --preset ci-clang \
+    -DCMAKE_EXPORT_COMPILE_COMMANDS=ON \
+    -DDD_TRACE_ENABLE_CLANG_TIDY=ON \
+    -DDD_TRACE_CLANG_TIDY="$tidy"
+
+cmake --build "$build_dir" --target dd-trace-cpp-objects -j

docs/development.md

@@ -22,3 +22,27 @@ command:
 ```shell
 bin/format
 ```
+
+To check formatting without writing files:
+
+```shell
+bin/check-format
+```
+
+## Static Analysis
+
+C++ is analyzed with **clang-tidy-14** (pinned; same major as `clang-format-14`)
+using the shared `.clang-tidy` baseline. Warnings are errors.
+
+Do not run clang-tidy on the host. Tidy must use the same compiler, flags, and
+stdlib as the real build (`ci-clang` + libc++). `bin/check-tidy` re-execs in
+`datadog/docker-library:dd-trace-cpp-ci-23768e9-*`, configures CMake there with
+`DD_TRACE_ENABLE_CLANG_TIDY`, and builds `dd-trace-cpp-objects` so CMake
+invokes `clang-tidy-14` with the exact compile line (first-party `src/` only):
+
+```shell
+bin/check-tidy
+```
+
+CI runs the same script in that image. A finding fails the pull request.
+