static-analysis

Static Analysis

Purpose

Guide agents through selecting, running, and triaging static analysis tools for C/C++ — clang-tidy, cppcheck, and scan-build — including suppression strategies and CI integration.

Triggers

• "How do I run clang-tidy on my project?"
• "What clang-tidy checks should I enable?"
• "cppcheck is reporting false positives — how do I suppress them?"
• "How do I set up scan-build for deeper analysis?"
• "My build is noisy with static analysis warnings"
• "How do I generate compile_commands.json for clang-tidy?"

Workflow

1. Generate compile_commands.json

clang-tidy requires a compilation database:

# CMake (preferred)
cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
ln -s build/compile_commands.json .

# Bear (for Make-based projects)
bear -- make

# compiledb (alternative for Make)
pip install compiledb
compiledb make

2. Run clang-tidy

# Single file
clang-tidy src/foo.c -- -std=c11 -I include/

# Whole project via compile_commands.json
run-clang-tidy -p build/ -j$(nproc)

# With specific checks enabled
clang-tidy -checks='bugprone-*,modernize-*,performance-*' src/foo.cpp

# Apply auto-fixes
clang-tidy -checks='modernize-use-nullptr' -fix src/foo.cpp

3. Check category decision tree

Goal?
├── Find real bugs            → bugprone-*, clang-analyzer-*
├── Modernise C++ code        → modernize-*
├── Follow core guidelines    → cppcoreguidelines-*
├── Catch performance issues  → performance-*
├── Security hardening        → cert-*, hicpp-*
└── Readability / style       → readability-*, llvm-*

Category	Key checks	What it catches
bugprone-*	use-after-move, integer-division, suspicious-memset-usage	Likely bugs
modernize-*	use-nullptr, use-override, use-auto	C++11/14/17 idioms
cppcoreguidelines-*	avoid-goto, pro-bounds-*, no-malloc	C++ Core Guidelines
performance-*	unnecessary-copy-initialization, avoid-endl	Performance regressions
clang-analyzer-*	core.*, unix.*, security.*	Path-sensitive bugs
cert-*	err34-c, str51-cpp	CERT coding standard

4. .clang-tidy configuration file

# .clang-tidy — place at project root
Checks: >
  bugprone-*,
  modernize-*,
  performance-*,
  -modernize-use-trailing-return-type,
  -bugprone-easily-swappable-parameters
WarningsAsErrors: 'bugprone-*,clang-analyzer-*'
HeaderFilterRegex: '^(src|include)/.*'
CheckOptions:
  - key: modernize-loop-convert.MinConfidence
    value: reasonable
  - key: readability-identifier-naming.VariableCase
    value: camelCase

5. Suppress false positives

// Suppress a single line
int result = riskyOp(); // NOLINT(bugprone-signed-char-misuse)

// Suppress a block
// NOLINTNEXTLINE(cppcoreguidelines-avoid-magic-numbers)
constexpr int BUFFER_SIZE = 4096;

// Suppress whole function
[[clang::suppress("bugprone-*")]]
void legacy_code() { /* ... */ }

Or in .clang-tidy:

# Exclude third-party directories
HeaderFilterRegex: '^(src|include)/.*'
# Disable specific checks
Checks: '-bugprone-easily-swappable-parameters'

6. Run cppcheck

# Basic run
cppcheck --enable=all --std=c11 src/

# With compile_commands.json
cppcheck --project=build/compile_commands.json

# Include specific checks and suppress noise
cppcheck --enable=warning,performance,portability \
         --suppress=missingIncludeSystem \
         --suppress=unmatchedSuppression \
         --error-exitcode=1 \
         src/

# Generate XML report for CI
cppcheck --xml --xml-version=2 src/ 2> cppcheck-report.xml

--enable= value	What it checks
warning	Undefined behaviour, bad practices
performance	Redundant operations, inefficient patterns
portability	Non-portable constructs
information	Configuration and usage notes
all	Everything above

7. Path-sensitive analysis with scan-build

# Intercept a Make build
scan-build make

# Intercept CMake build
scan-build cmake --build build/

# Show HTML report
scan-view /tmp/scan-build-*/

# With specific checkers
scan-build -enable-checker security.insecureAPI.gets \
           -enable-checker alpha.unix.cstring.BufferOverlap \
           make

scan-build finds deeper bugs than clang-tidy: use-after-free across functions, dead stores from logic errors, null dereferences on complex paths.

8. CI integration

# GitHub Actions
- name: Static analysis
  run: |
    cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
    run-clang-tidy -p build -j$(nproc) -warnings-as-errors '*'

- name: cppcheck
  run: |
    cppcheck --enable=warning,performance \
             --suppress=missingIncludeSystem \
             --error-exitcode=1 \
             src/

For clang-tidy check details, see references/clang-tidy-checks.md.

Related skills

• Use skills/compilers/clang for Clang toolchain and diagnostic flags
• Use skills/compilers/gcc for GCC warnings as complementary analysis
• Use skills/runtimes/sanitizers for runtime bug detection alongside static analysis
• Use skills/build-systems/cmake for CMAKE_EXPORT_COMPILE_COMMANDS setup