.. title:: clang-tidy - modernize-use-transparent-functors

modernize-use-transparent-functors
==================================

Prefer transparent functors to non-transparent ones. When using transparent
functors, the type does not need to be repeated. The code is easier to read,
maintain and less prone to errors. It is not possible to introduce unwanted
conversions.

.. code-block:: c++

    // Non-transparent functor
    std::map<int, std::string, std::greater<int>> s;

    // Transparent functor.
    std::map<int, std::string, std::greater<>> s;

    // Non-transparent functor
    using MyFunctor = std::less<MyType>;

It is not always a safe transformation though. The following case will be
untouched to preserve the semantics.

.. code-block:: c++

    // Non-transparent functor
    std::map<const char *, std::string, std::greater<std::string>> s;

Options
-------

.. option:: SafeMode

  If the option is set to non-zero, the check will not diagnose cases where
  using a transparent functor cannot be guaranteed to produce identical results
  as the original code. The default value for this option is `0`.

This check requires using C++14 or higher to run.