cpp-linter/C/C++ Linter
Linting C/C++ code with clang-tidy or clang-format to give feedback as comments, PR reviews, and more.
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- Activelast commit Jul 4, 2026
- License
- MIT
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uses: cpp-linter/cpp-linter-action@8e85cd02c8c3fe3ae527c94b5683fe2366b144ed # v2.20.0tags can be moved; commit SHAs can't. why a SHA?
Inputs
| name | description | required | default |
|---|---|---|---|
| style | The style rules to use. - Set this to `file` to have clang-format use the closest relative .clang-format file. - Set this to a blank string (`''`) to disable the use of clang-format entirely. - Any code style supported by the specified version of clang-format. | no | llvm |
| extensions | The file extensions to run the action against. This is a comma-separated string. | no | c,h,C,H,cpp,hpp,cc,hh,c++,h++,cxx,hxx |
| tidy-checks | Comma-separated list of globs with optional `-` prefix. Globs are processed in order of appearance in the list. Globs without `-` prefix add checks with matching names to the set, globs with the `-` prefix remove checks with matching names from the set of enabled checks. This option's value is appended to the value of the 'Checks' option in a .clang-tidy file (if any). - It is possible to disable clang-tidy entirely by setting this option to `'-*'`. - It is also possible to rely solely on a .clang-tidy config file by specifying this option as a blank string (`''`). | no | boost-*,bugprone-*,performance-*,readability-*,portability-*,modernize-*,clang-analyzer-*,cppcoreguidelines-* |
| repo-root | The relative path to the repository root directory. This path is relative to the path designated as the runner's `GITHUB_WORKSPACE` environment variable. | no | . |
| version | The desired version of the [clang-tools](https://github.com/cpp-linter/clang-tools-pip) to use. Accepted options are strings which can be 22, 21, 20, 19, 18, 17, 16, 15, 14, 13 or 12. - Set this option to a blank string (`''`) to use the platform's default installed version. - This value can also be a path to where the clang tools are installed (if using a custom install location). | no | 21 |
| verbosity | This controls the action's verbosity in the workflow's logs. Supported options are `info` or `debug`. This option does not affect the verbosity of resulting thread comments or file annotations. The verbosity can also be engaged by enabling debug logs when [re-running jobs or workflows](https://docs.github.com/en/actions/managing-workflow-runs/re-running-workflows-and-jobs). | no | info |
| lines-changed-only | This controls what part of the files are analyzed. The following values are accepted: - `false`: All lines in a file are analyzed. - `true`: Only lines in the diff that contain additions are analyzed. - `diff`: All lines in the diff are analyzed (including unchanged lines but not subtractions). !!! info "Important" This feature requires special permissions to perform successfully. See our [documented permissions](permissions.md) | no | false |
| files-changed-only | Set this option to false to analyze any source files in the repo. This is automatically enabled if [`lines-changed-only`](#lines-changed-only) is enabled. !!! info "Important" This feature requires special permissions to perform successfully. See our [documented permissions](permissions.md) | no | true |
| ignore | Set this option with string of path(s) to ignore. - In the case of multiple paths, you can use a pipe character (`|`) to separate the multiple paths. Multiple lines are forbidden as an input to this option; it must be a single string. - This can also have files, but the file's relative path has to be specified as well. - There is no need to use `./` for each entry; a blank string (`''`) represents the [`repo-root`](#repo-root) path. - Submodules are automatically ignored. Hidden directories (beginning with a `.`) are also ignored automatically. - Prefix a path with a bang (`!`) to make it explicitly _not_ ignored. The order of multiple paths does _not_ take precedence. The `!` prefix can be applied to a submodule's path (if desired) but not hidden directories. - **As of v2.12**, glob patterns are supported here. All asterisk characters (`*`) were previously literal. | no | .github |
| ignore-tidy | Use this option to allow clang-tidy to ignore certain paths/files. See [`ignore`](#ignore) for more details on possible values. | no | .github |
| ignore-format | Use this option to allow clang-format to ignore certain paths/files. See [`ignore`](#ignore) for more details on possible values. | no | .github |
| thread-comments | This controls the behavior of posted thread comments as feedback. The following options are supported: - `true`: enable the use of thread comments. This will always delete an outdated thread comment and post a new comment (triggering a notification for every comment). - `update`: update an existing thread comment if one already exists. This option does not trigger a new notification for every thread comment update. - `false`: disable the use of thread comments. !!! info "Important" This feature requires special permissions to perform successfully. See our [documented permissions](permissions.md) > [!NOTE] > If run on a private repository, then this feature is disabled because the GitHub REST API behaves differently for thread comments on a private repository. | no | false |
| no-lgtm | Set this option to true or false to enable or disable the use of a thread comment or pull request review that basically says 'Looks Good To Me' (when all checks pass). The default value, `true` means no LGTM comment posted. See [`thread-comments`](#thread-comments), [`tidy-review`](#tidy-review), and [`format-review`](#format-review) options for further details. | no | true |
| step-summary | Set this option to true to append content as part of workflow's job summary. See implementation details in GitHub's documentation about [Adding a job summary](https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#adding-a-job-summary). This option is independent of the [`thread-comments`](#thread-comments) option, rather this option uses the same content that the [`thread-comments`](#thread-comments) option would use. > [!NOTE] > The [`no-lgtm`](#no-lgtm) option is _not_ applied to step summaries. | no | false |
| file-annotations | Set this option to false to disable the use of file annotations as feedback. | no | true |
| database | The directory containing compilation database (like compile_commands.json) file. | no | "" |
| extra-args | A string of extra arguments passed to clang-tidy for use as compiler arguments. Multiple arguments are separated by spaces so the argument name and value should use an `=` sign instead of a space. !!! example ``` yaml extra-args: '-std=c++17 -Wall' ``` This will be passed to clang-tidy as multiple `--extra-arg` options: ``` clang-tidy --extra-arg=-std=c++17 --extra-arg=-Wall ``` | no | "" |
| tidy-review | Set this option to `true` to enable Pull Request reviews from clang-tidy. !!! info "Important" This feature requires special permissions to perform successfully. See our [documented permissions](permissions.md). See also [the PR review feature caveats](pr-review-caveats.md). > [!NOTE] > The [`no-lgtm`](#no-lgtm) option is applicable to Pull Request reviews. | no | false |
| format-review | Set this option to `true` to enable Pull Request reviews from clang-format. !!! info "Important" This feature requires special permissions to perform successfully. See our [documented permissions](permissions.md). See also [the PR review feature caveats](pr-review-caveats.md). > [!NOTE] > The [`no-lgtm`](#no-lgtm) option is applicable to Pull Request reviews. | no | false |
| passive-reviews | Set this option to `true` to prevent Pull Request reviews from approving or requesting changes. | no | false |
| jobs | The number of jobs to run in parallel. If less than or equal to 0, the number of jobs is set to use the number of all available CPU cores. | no | 0 |
| cache-enable | Controls the caching of cpp-linter dependencies. The installed `clang-format` and `clang-tidy` tools are not cached. By default, this is enabled. Any cached assets are kept within the path to this action's source (not in the runner's workspace or temp directory). | no | true |
| summary-output-file | Supply a path to which the step summary will be written. Leave empty to not write summary to a file. > [!NOTE] > Any relative path shall be relative to the [`repo-root`](#repo-root) path. | no | "" |
Outputs
| name | description |
|---|---|
| checks-failed | An integer that can be used as a boolean value to indicate if any checks failed by clang-tidy and clang-format. |
| clang-tidy-checks-failed | An integer that can be used as a boolean value to indicate if any checks failed by clang-tidy only. |
| clang-format-checks-failed | An integer that can be used as a boolean value to indicate if any checks failed by clang-format only. |