CMake/Help/policy/CMP0018.rst

CMP0018
-------

Ignore CMAKE_SHARED_LIBRARY_<Lang>_FLAGS variable.

CMake 2.8.8 and lower compiled sources in SHARED and MODULE libraries
using the value of the undocumented CMAKE_SHARED_LIBRARY_<Lang>_FLAGS
platform variable.  The variable contained platform-specific flags
needed to compile objects for shared libraries.  Typically it included
a flag such as -fPIC for position independent code but also included
other flags needed on certain platforms.  CMake 2.8.9 and higher
prefer instead to use the POSITION_INDEPENDENT_CODE target property to
determine what targets should be position independent, and new
undocumented platform variables to select flags while ignoring
CMAKE_SHARED_LIBRARY_<Lang>_FLAGS completely.

The default for either approach produces identical compilation flags,
but if a project modifies CMAKE_SHARED_LIBRARY_<Lang>_FLAGS from its
original value this policy determines which approach to use.

The OLD behavior for this policy is to ignore the
POSITION_INDEPENDENT_CODE property for all targets and use the
modified value of CMAKE_SHARED_LIBRARY_<Lang>_FLAGS for SHARED and
MODULE libraries.

The NEW behavior for this policy is to ignore
CMAKE_SHARED_LIBRARY_<Lang>_FLAGS whether it is modified or not and
honor the POSITION_INDEPENDENT_CODE target property.

This policy was introduced in CMake version 2.8.9.  CMake version
|release| warns when the policy is not set and uses OLD behavior.  Use
the cmake_policy command to set it to OLD or NEW explicitly.

.. include:: DEPRECATED.txt