[clang-tools-extra] [llvm] New check `misc-header-guard` (PR #177315)

[via cfe-commits]

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+.. title:: clang-tidy - llvm-header-guard
+
+misc-header-guard
+=================
+
+Finds and fixes header guards.
+
+Options
+-------
+
+.. option:: HeaderDirs
+
+   A semicolon-separated list of one or more header directory names.
+   Header directories may contain `/` as path separator.
+   The list is searched for the first matching string.
+   The header guard will start from this path component.
+   Default value is `include`.
+
+.. option:: Prefix
+
+   A string specifying an optional prefix that is applied to each header guard.
+   Default is an empty string.
+
+.. option:: EndifComment
+
+   A boolean that controls whether the endif namespace comment is suggested.
+   Default value is `false`.
+
+.. option:: AllowPragmaOnce
+
+   A boolean that controls whether ``#pragma once`` directive is allowed.
+   Default value is `false`.
+
+Examples
+--------
+
+Header file: ``/path/to/include/component/header.hpp``:
+
+By default, the check ensures following header guard:
+
+.. code-block:: c++
+
+  #ifndef COMPONENT_HEADER_HPP
+  #define COMPONENT_HEADER_HPP
+  ...
+  # endif
+
+E.g. :option:`HeaderDirs` is set to following values:
+
+- `component`
+- `include/component`
+- `component;include`
+
+.. code-block:: c++
+
+  #ifndef HEADER_HPP
+  #define HEADER_HPP
+  ...
+  # endif
+
+E.g. :option:`HeaderDirs` is set to one of the following values:
+
+- `component`
+- `include/component`
+- `component;include`
+
+.. code-block:: c++
+
+  #ifndef HEADER_HPP
+  #define HEADER_HPP
+  ...
+  # endif
+
+.. warning::
+  The .:option:`HeaderDirs` list is searched until first directory name matches
+  the header file path. If `HeaderDirs` is set to `include;component`, the
+  check will result in default behavior (since `include` is found first).
+
+
----------------
EugeneZelenko wrote:

```suggestion
```

https://github.com/llvm/llvm-project/pull/177315