.. title:: clang-tidy - misc-unused-raii

misc-unused-raii
================

Finds temporaries that look like RAII objects.

The canonical example for this is a scoped lock.

.. code-block:: c++

  {
    scoped_lock(&global_mutex);
    critical_section();
  }

The destructor of the scoped_lock is called before the ``critical_section`` is
entered, leaving it unprotected.

We apply a number of heuristics to reduce the false positive count of this
check:

- Ignore code expanded from macros. Testing frameworks make heavy use of this.

- Ignore types with trivial destructors. They are very unlikely to be RAII
  objects and there's no difference when they are deleted.

- Ignore objects at the end of a compound statement (doesn't change behavior).

- Ignore objects returned from a call.