# Header Guards

This linter checks for missing header guards in C, C++ and objective C headers.
This enforces the principle edict in our coding style.

## Principle

If a header file (`.h` or `.hpp` extension) purged from comment does not
begin with `#pragma once`, `#ifndef SOME_GUARD` or `#if !defined(SOME_GUARD)`,
it is considered an error.

## Run Locally

The mozlint integration of this linter can be run using `mach`:

```{eval-rst}
.. parsed-literal::

    $ mach lint --linter header-guards <file paths>

```

## Autofix

The `header-guards` linter provides a `--fix` option.

## Builders

[Serge Guelton (sergesanspaille)](https://people.mozilla.org/p/sergesanspaille) owns
the builders. Questions can also be asked on #static-analysis:mozilla.org on Matrix.

### cpp(guards)

This is a tier-1 task. For test failures the patch causing the
issue should be backed out or the issue fixed.

Most failures can be fixed with `./mach lint -lheader-guards --fix path/to/file`.

For test harness issues, file bugs in Developer Infrastructure :: Lint and Formatting.

## Sources

- {searchfox}`Linter Configuration (YAML) <tools/lint/header-guards.yml>`
- {searchfox}`Source <tools/lint/header_guards/__init__.py>`