CMake Variable Reference

Module variables

Qt modules loaded with find_package set various variables.

Note: You rarely need to access these variables directly. Common tasks like linking against a module should be done through the library targets each module defines.

For example, find_package(Qt5 COMPONENTS Widgets), when successful, makes the following variables available:

VariableDescription
Qt5Widgets_COMPILE_DEFINITIONSA list of compile definitions to use when building against the library.
Qt5Widgets_DEFINITIONSA list of definitions to use when building against the library.
Qt5Widgets_EXECUTABLE_COMPILE_FLAGSA string of flags to use when building executables against the library.
Qt5Widgets_FOUNDA boolean that describes whether the module was found successfully.
Qt5Widgets_INCLUDE_DIRSA list of include directories to use when building against the library.
Qt5Widgets_LIBRARIESThe name of the imported target for the module: Qt5::Widgets
Qt5Widgets_PRIVATE_INCLUDE_DIRSA list of private include directories to use when building against the library and using private Qt API.
Qt5Widgets_VERSION_STRINGA string containing the module's version.

For all packages found with find_package, equivalents of these variables are available; they are case-sensitive.

Installation variables

Additionally, there are also variables that don't relate to a particular package, but to the Qt installation itself.

VariableDescription
QT_DEFAULT_MAJOR_VERSIONAn integer that controls the Qt version that qt_ commands forward to in case of mixed Qt 5 and Qt 6 projects. It needs to be set to either 5 or 6 before the respective find_package() calls.

If set to 5, commands starting with qt_ will call their counterpart starting with qt5_. If set to 6, they will call their counterpart starting with qt6_.

If not set, the first find_package call defines the default version. This functionality was added in Qt 5.15.

QT_LIBINFIXA string that holds the infix used in library names, when Qt is configured with -libinfix.
QT_NO_CREATE_VERSIONLESS_FUNCTIONSSince Qt 5.15, modules define not only commands that start with qt5_, but also ones with qt_. You can set QT_NO_CREATE_VERSIONLESS_FUNCTIONS before find_package to prevent this.
QT_NO_CREATE_VERSIONLESS_TARGETSSince Qt 5.15, modules define not only targets that start with Qt5::, but also ones with Qt::. You can set QT_NO_CREATE_VERSIONLESS_TARGETS before find_package to prevent this.
QT_VISIBILITY_AVAILABLEOn Unix, a boolean that describes whether Qt libraries and plugins were compiled with -fvisibility=hidden. This means that only selected symbols are exported.

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