..
  Copyright 1988-2022 Free Software Foundation, Inc.
  This is part of the GCC manual.
  For copying conditions, see the copyright.rst file.

.. _implementation-details:

Implementation Details
----------------------

Here we document details of how the preprocessor's implementation
affects its user-visible behavior.  You should try to avoid undue
reliance on behavior described here, as it is possible that it will
change subtly in future implementations.

Also documented here are obsolete features still supported by CPP.

.. toctree::
  :maxdepth: 2

  implementation-defined-behavior
  implementation-limits
  obsolete-features