codeguard-cpp

C++ Codeguard Gate

Goal: turn "it looks fine" into repeatable tool evidence, and honestly distinguish pass, fail, unverifiable, and planned.

30-second start

1. At the repository root, confirm 无专用标记文件 or the target file exists.
2. Probe tools:clang-tidy --version。
3. First do a read-only check:bash -c 'find . \( -name '"'"'*.cpp'"'"' -o -name '"'"'*.hpp'"'"' -o -name '"'"'*.cc'"'"' \) -type f -print0 | xargs -0 -r clang-tidy --quiet'。
4. Classify the results as: code violations, missing configuration, missing tools, tool internal errors.
5. Only perform safe-to-fix items:clang-format -i '{file}'。
6. Rerun lint, and run the project's existing test/build gates.

You can directly propose:

• "Check this C++ project, do not modify anything first, give me the lint failure classification."
• "Only fix C++ formatting issues, list semantic issues first."
• "Verify C++ lint, test, and build evidence before committing."

Capability boundaries

✅ Good at handling

1. Based on .cpp, .hpp, .cc and project markers, identify the C++ workspace.
2. Run clang-tidy --quiet '{file}' and keep the exit code, scope, and tool version.
3. Distinguish formatting, static rule, configuration, dependency, and environment failures.
4. Use clang-format -i '{file}' to handle reversible issues and rescan.
5. Report local results in layers with CI/build/test evidence.

⚠️ Requires conditions

1. The target tool must be installed and its version compatible with the project constraints.
2. Must be run from the correct repository or module root.
3. If the project has custom configuration, the committed configuration prevails.
4. Whether generated code, vendor, and cache directories are scanned must follow repository rules.

❌ Not applicable

1. Do not treat formatter passing as compilation, test, or security audit passing.
2. Do not silently install tools, upgrade dependencies, or modify team rules.
3. Do not use suppress/ignore/raising thresholds to hide real problems.
4. Do not claim "checks passed" when tools or configuration are missing.

When to use

• The user requests checking or fixing C++ code standards.
• AI modified .cpp, .hpp, .cc, and pre-commit verification is needed.
• CI has failures related to clang-tidy --quiet '{file}' .
• Need to determine whether a problem can be fixed automatically or must be handled manually.

When not to use

• If the main task is learning language syntax, framework design, or business modeling, use the corresponding language professional skill instead.
• If the main task is dependency vulnerabilities, security auditing, or license governance, use a dedicated security skill.
• When the user only asks to explain one error and there is no project context, give a local explanation first and do not claim the whole repository is green.

Data and security

This skill does not collect, upload, send, or store user code and credentials. By default it only reads local repository configuration and runs local tools; it does not install dependencies over the network, and does not record tokens, passwords, or private source code. Before any automatic fix, check the diff first; destructive or large-scale changes must be explicitly confirmed by the user.

Execution Contract

Item	Current Facts
Status	stable(Since Codeguard V0.4)
File Extensions	.cpp, .hpp, .cc
Project Marker	No dedicated marker file
Integration Config	Based on the repository's existing configuration
Tool Preparation	clang-tidy + clang-format
Detection Command	使用命令查找与项目配置检查
lint	clang-tidy --quiet '{file}'
format/fix	clang-format -i '{file}'
Project-level gate	bash -c 'find . \( -name '"'"'*.cpp'"'"' -o -name '"'"'*.hpp'"'"' -o -name '"'"'*.cc'"'"' \) -type f -print0 | xargs -0 -r clang-tidy --quiet'

Standard Workflow

Step 1: Determine the Real Scope

Confirm the repository root, module roots, generated directories, vendor directories, and user-specified files. For multi-module projects, first list the modules to be scanned; do not guess based on the current directory.

Step 2: Read the Project Contract

Read the actual commands in the repository's existing configuration and CI. Repository configuration takes precedence over this skill's examples; if the two conflict, report the discrepancy first.

Step 3: Detect Tools and Versions

Run 对应工具 --version. Missing tools, incompatible versions, or configurations that fail to load are all recorded as "unable to verify", not as passing.

Step 4: Run Read-Only Checks

Run bash -c 'find . \( -name '"'"'*.cpp'"'"' -o -name '"'"'*.hpp'"'"' -o -name '"'"'*.cc'"'"' \) -type f -print0 | xargs -0 -r clang-tidy --quiet', recording the command, working directory, exit code, tool version, and the first actionable error.

Step 5: Failure Classification

Type	Typical Signal	Handling
Format	Indentation, whitespace, import order	Allow formatter, then check the diff
Static Rules	unused, complexity, naming, dangerous APIs	Minimal semantic fixes, no batch guessing
Configuration	parser/config/schema not found	Fix integration or report prerequisites
Environment	command not found, version conflicts	Report installation/version requirements, do not install silently
Tool Internal Errors	crash, timeout, parser exceptions	Preserve raw evidence, narrow the reproduction scope

Step 6: Controlled Fixes

Prefer running clang-format -i '{file}'. Only handle issues that are certain and reversible; dependency upgrades, rule exemptions, generated files, and business semantic changes must be explained separately.

Step 7: Verification Loop

Re-run the same lint command, then run the project's existing tests and build. Only write "passed" when the command, scope, and exit code are all clear; otherwise write "not run" or "unable to verify".

Rules

1. Re-verify with the same command: After fixing, you must re-run the original command that triggered the failure.
2. Evidence layering: Report lint, format, compile, test, and security separately.
3. Minimal changes: Do not refactor along the way, and do not expand style fixes into business rewrites.
4. Configuration first: Do not override the project's existing ignore, dialect, target, or version constraints.
5. No fabrication: Tools not run, configurations not seen, and platforms not verified must be clearly marked.

Output Template

C++ Codeguard 结果
- 范围：<仓库/模块/文件>
- 工具：<名称与版本>
- 命令：<实际命令>
- 状态：PASS / FAIL / UNVERIFIED / PLANNED
- 发现：<按格式/规则/配置/环境分类>
- 修改：<文件与原因；无修改写 none>
- 复验：<命令、退出码>
- 未验证：<测试/构建/平台差异>

Gotchas

1. Missing tools are not a pass — must output UNVERIFIED and a clear preparation method.
2. formatter is not a linter — All green formatting cannot override static rules or compilation errors.
3. Root directory determines the result — Running in the wrong module may miss issues or load the wrong configuration.
4. Placeholders are not literal arguments — {file} must be replaced with real, authorized paths.
5. Auto-fix may expand the diff — After fixing, review the diff first, then run the regression gate.
6. Generated and vendor directories require explicit policy — Do not scan or modify third-party content across the whole repository at will.

Domain pitfalls and fixes

1. Domain pitfalls — Templates, macros, and conditional compilation depend heavily on a real compilation database; do not declare success based on default parameters from a single file.

When information is insufficient

Do not just say "please provide more information." First give a safe, read-only inspection plan, and list the specific items that still need confirmation:

1. Repository/module root directory;
2. Target tool and version;
3. Project configuration files;
4. The authoritative command in CI;
5. Whether auto-fix is allowed.

FAQ

Q1: If the tool is not installed, can we conclude the code is fine? No. The status must be UNVERIFIED。

Q2: Can ignore or suppression be added automatically? No. Exemptions may only be granted when the user explicitly accepts them and the reason is recorded.

Q3: Why does it still fail after formatting? The formatter only covers formatting; static rules, configuration, compilation, and tests still need to be handled separately.

Q4: Should generated code be scanned? By default, follow the repository configuration; if there is no rule, exclude generated/vendor first, then explain to the user.

Q5: How can too many changes at once be avoided? Fix in batches by failure category and file, rerunning the original command and reviewing the diff for each batch.

Q6: If it passes locally, can we say CI will pass? No. You also need to align CI's version, environment variables, operating system, and command scope.

Load resources on demand

• When encountering exit codes, failure classification, or exemption decisions, read references/rules/gate-rules.md。
• When you need to verify this language's registry, toolchain, and project configuration, read references/tooling/toolchain.md。
• When you need copyable task examples, read by scenario examples/, there is no need to load everything at once.