CMP0018 — CMake 4.0.1 Documentation (original) (raw)

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>_FLAGSplatform 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 ignoringCMAKE_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 thePOSITION_INDEPENDENT_CODE property for all targets and use the modified value of CMAKE_SHARED_LIBRARY_<Lang>_FLAGS for SHARED andMODULE libraries.

The NEW behavior for this policy is to ignoreCMAKE_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. Prior to removal in CMake version 4.0, it could be set by cmake_policy() or cmake_minimum_required(). If it was not set, CMake warned, and used OLD behavior.