- Qt 6.9
- Qt Core
- QTP0003
- Qt 6.9.3 Reference Documentation

# QTP0003

Consider the BUILD_SHARED_LIBS value when creating Qt libraries.

This policy was introduced in Qt 6.7. The policy affects the default type of the libraries created using Qt CMake API, like qt_add_library, qt_add_plugin, qt_add_qml_module.

If the policy is set to `OLD`, the default library type that is selected is aligned with the Qt build type, either `shared` or `static`.

If the policy is set to `NEW`, the library type is selected according to the BUILD_SHARED_LIBS value if it's set. If `BUILD_SHARED_LIBS` is not set, the default library type falls back to the Qt build type.

For example, the following code will use the Qt build type as the default library type for the `MyLib` target, despite the fact `BUILD_SHARED_LIBS` is set to `ON`:

     set(BUILD_SHARED_LIBS ON)
     ...
     qt6_add_library(MyLib sourcefile.h sourcefile.cpp)

If you set the QTP0003 to `NEW` before the qt_add_library call, `BUILD_SHARED_LIBS` will affect the library default type and `MyLib` will be the shared library.

     set(BUILD_SHARED_LIBS ON)
     ...
     qt_policy(SET QTP0003 NEW)
     qt6_add_library(MyLib sourcefile.h sourcefile.cpp)

See also qt_policy, Qt CMake policies, and qt_add_library.