# Lint

### Lint Config

The `lint` section of `.trunk/trunk.yaml` represents the configuration of all linters. This is where you can:

* Define the linters (`lint.definitions`),
* List linters to enable and disable (`lint.enabled` and `lint.disabled`)
* Define file categories (`lint.files`)
* List required `runtimes` and `downloads`.
* And additional cross-linter settings.

### `bazel`

`bazel`: bazel configuration

* `paths` locations to look for Bazel binary. [Example](https://docs.trunk.io/code-quality/linters/supported/clang-tidy#using-bazel).

### `comment_formats`

`comment_formats`: Definitions of comment formats. Reused in linter definitions. Trunk Quality already defines many common comment format such as `hash` (`# comment`), `slashes-block` (`/* comment */`), and `slashes-inline` (`// comment`). For the full list [see the linters plugin.yaml](https://github.com/trunk-io/plugins/blob/main/linters/plugin.yaml).

To create a new comment format provide the name and delimiters like this:

```yaml
lint:
  comment_formats:
    - name: dashes-block
      leading_delimiter: --[[
      trailing_delimiter: --]
```

### `compile_commands`

`compile_commands`: compile commands for clang-tidy. Must be one of `json` or `bazel`.

### `compile_commands_roots`

`compile_commands_roots`: Directories to search for `compile_commands.json`. The default is `build/`.

### `default_max_file_size`

`default_max_file_size`: Default maximum filesize in bytes. Trunk Code Quality will not run linters on any files larger than this. Default value is 4 megabytes.

### `definitions`

`definitions`: Where you define or override linter settings. See [Linter Definition Config](https://docs.trunk.io/code-quality/overview/getting-started/configuration/lint/definitions).

### `disabled`

`disabled`: The list of linters to disable. Adding a linter here will prevent trunk from suggesting it as a new linter each time you upgrade. Linter names can be in the form of `<name>` or `<name>@<version>`, the same format as the [enabled](#enabled) property.

### `downloads`

`downloads`: Locations to download binary artifacts from. Using [tool definitions](https://docs.trunk.io/code-quality/overview/getting-started/configuration/tools) instead is preferred.

### `enabled`

`enabled`: The list of linters to enable. Linter names can be in the form of `<name>` or `<name>@<version>`. Examples:

```yaml
lint:
  enabled:
    # Mutually exclusive, choose one:
    - eslint # Use the system version of markdownlint
    - eslint@9.0.0 # Use a hermetically managed version of eslint
    - eslint@node # Use eslint from node_modules/.bin
```

### `exported_configs`

`exported_configs`: Linter configs to export when another project is [importing this plugin](https://docs.trunk.io/code-quality/overview/linters/shared-configs)

### `extra_compilation_flags`

`extra_compilation_flags`: When running clang-tidy, this list will be appended to the compile command.

### `files`

`files`: Definitions of filetypes

Every linter must define the set of filetypes it applies to in the `lint.files` section.

New filetypes are defined with the name and extensions properties. They may also include the comments properties to describe what style of comments are used in these files.

This is how the C++ source filetype is defined. See also [Files and Caching](https://docs.trunk.io/code-quality/overview/getting-started/configuration/lint/files-and-caching).

```yaml
lint:
  files:
    - name: c++-source
      extensions:
        - C
        - cc
        - cpp
        - cxx
      comments:
        - slashes-block
        - slashes-inline
```

### `ignore`

`ignore`: files to be ignored by linters.

### `reuse_upstream`

`reuse_upstream`: If enabled, Trunk will cache upstream sandboxes instead of creating a new one each time. Options are `true`, or `false`.

### `runtimes`

`runtimes`: Node, python, cargo, etc. Used to define or override a runtime environment for package management. [See Runtimes](https://docs.trunk.io/code-quality/overview/getting-started/configuration/runtimes).

### `skip_missing_compile_command`

`skip_missing_compile_command`: For linters that depend on compile commands, setting this will cause Trunk to skip files without a compile command rather than report an error.

### `threshold`

`threshold`: where you specify the blocking behavior of linters. The [threshold](https://docs.trunk.io/code-quality/linters/configure-linters#blocking-thresholds) for whether an error from a linter should block commits or not.

### `upstream_mode`

`upstream_mode`: How to generate the upstream sandbox used for generating lint results for revisions not currently checked out. Options are`symlink` (default), `hardlink`, or `copy`. If using `copy`, it can be slow without also enabling `reuse_upstream: true`.