CMP0020

Warning

The OLD behavior of this policy was removed in CMake version 4.0. This policy must be set to NEW by a call to cmake_minimum_required() or cmake_policy().

Automatically link Qt executables to qtmain target on Windows.

CMake 2.8.10 and lower required users of Qt to always specify a link dependency to the qtmain.lib static library manually on Windows. CMake 2.8.11 gained the ability to evaluate generator expressions while determining the link dependencies from IMPORTED targets. This allows CMake itself to automatically link executables which link to Qt to the qtmain.lib library when using IMPORTED Qt targets. For applications already linking to qtmain.lib, this should have little impact. For applications which supply their own alternative WinMain implementation and for applications which use the QAxServer library, this automatic linking will need to be disabled as per the documentation.

The OLD behavior for this policy is not to link executables to qtmain.lib automatically when they link to the QtCore IMPORTED target. The NEW behavior for this policy is to link executables to qtmain.lib automatically when they link to QtCore IMPORTED target.

This policy was introduced in CMake version 2.8.11. 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.