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Help: Autogen: Overhaul AUTOMOC target property documentation
- Rewrites and restructures the AUTOMOC target property documentation - Remove the reference to the deprecated CMAKE_AUTOMOC_RELAXED_MODE Fixes: #19167
This commit is contained in:
Sebastian Holtermann
committed by
Brad King
Brad King
parent
fdab21f30b
commit
b55e5d6641
@@ -1,97 +1,247 @@
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AUTOMOC
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-------
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Should the target be processed with automoc (for Qt projects).
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Should the target be processed with auto-moc (for Qt projects).
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:prop_tgt:`AUTOMOC` is a boolean specifying whether CMake will handle the Qt
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``moc`` preprocessor automatically, i.e. without having to use the
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:module:`QT4_WRAP_CPP() <FindQt4>` or QT5_WRAP_CPP() macro.
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:module:`QT4_WRAP_CPP() <FindQt4>` or ``QT5_WRAP_CPP()`` macro.
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Currently Qt4 and Qt5 are supported.
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When this property is set ``ON``, CMake will scan the header and
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source files at build time and invoke moc accordingly.
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* If an ``#include`` statement like ``#include "moc_<basename>.cpp"`` is found,
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a macro from :prop_tgt:`AUTOMOC_MACRO_NAMES` is expected to appear in the
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``<basename>.h(xx)`` header file. ``moc`` is run on the header
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file to generate ``moc_<basename>.cpp`` in the
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``<AUTOGEN_BUILD_DIR>/include`` directory which is automatically added
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to the target's :prop_tgt:`INCLUDE_DIRECTORIES`.
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This allows the compiler to find the included ``moc_<basename>.cpp`` file
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regardless of the location the original source.
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* For :prop_gbl:`multi configuration generators <GENERATOR_IS_MULTI_CONFIG>`,
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the include directory is ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``.
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* See :prop_tgt:`AUTOGEN_BUILD_DIR`.
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* If an ``#include`` statement like ``#include "<basename>.moc"`` is found,
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a macro from :prop_tgt:`AUTOMOC_MACRO_NAMES` is expected to appear in the
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source file and ``moc`` is run on the source file itself.
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* Header files that are not included by an ``#include "moc_<basename>.cpp"``
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statement are nonetheless scanned for a macro out of
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:prop_tgt:`AUTOMOC_MACRO_NAMES`.
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The resulting ``moc_<basename>.cpp`` files are generated in custom
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directories and automatically included in a generated
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``<AUTOGEN_BUILD_DIR>/mocs_compilation.cpp`` file,
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which is compiled as part of the target.
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* The custom directories with checksum
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based names help to avoid name collisions for ``moc`` files with the same
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``<basename>``.
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* See :prop_tgt:`AUTOGEN_BUILD_DIR`.
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* Additionally, header files with the same base name as a source file,
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(like ``<basename>.h``) or ``_p`` appended to the base name (like
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``<basename>_p.h``), are scanned for a macro out of
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:prop_tgt:`AUTOMOC_MACRO_NAMES`, and if found, ``moc``
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is also executed on those files.
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* ``AUTOMOC`` always checks multiple header alternative extensions,
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such as ``hpp``, ``hxx``, etc. when searching for headers.
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* ``AUTOMOC`` looks for the ``Q_PLUGIN_METADATA`` macro and reruns the
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``moc`` when the file addressed by the ``FILE`` argument of the macro changes.
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This property is initialized by the value of the :variable:`CMAKE_AUTOMOC`
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variable if it is set when a target is created.
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When this property is set ``ON``, CMake will scan the header and
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source files at build time and invoke ``moc`` accordingly.
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Header file processing
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^^^^^^^^^^^^^^^^^^^^^^
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At configuration time, a list of header files that should be scanned by
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:prop_tgt:`AUTOMOC` is computed from the target's sources.
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- All header files in the target's sources are added to the scan list.
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- For all C++ source files ``<source_base>.<source_extension>`` in the
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target's sources, CMake searches for
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- a regular header with the same base name
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(``<source_base>.<header_extention>``) and
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- a private header with the same base name and a ``_p`` suffix
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(``<source_base>_p.<header_extention>``)
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and adds these to the scan list.
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At build time, CMake scans each unknown or modified header file from the
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list and searches for
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- a Qt macro from :prop_tgt:`AUTOMOC_MACRO_NAMES`,
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- additional file dependencies from the ``FILE`` argument of a
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``Q_PLUGIN_METADATA`` macro and
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- additional file dependencies detected by filters defined in
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:prop_tgt:`AUTOMOC_DEPEND_FILTERS`.
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If a Qt macro is found, then the header will be compiled by the ``moc`` to the
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output file ``moc_<base_name>.cpp``. The complete output file path is
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described in the section `Output file location`_.
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The header will be ``moc`` compiled again if a file from the additional file
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dependencies changes.
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Header ``moc`` output files ``moc_<base_name>.cpp`` can be included in source
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files. In the section `Including header moc files in sources`_ there is more
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information on that topic.
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Source file processing
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^^^^^^^^^^^^^^^^^^^^^^
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At build time, CMake scans each unknown or modified C++ source file from the
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target's sources for
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- a Qt macro from :prop_tgt:`AUTOMOC_MACRO_NAMES`,
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- includes of header ``moc`` files
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(see `Including header moc files in sources`_),
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- additional file dependencies from the ``FILE`` argument of a
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``Q_PLUGIN_METADATA`` macro and
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- additional file dependencies detected by filters defined in
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:prop_tgt:`AUTOMOC_DEPEND_FILTERS`.
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If a Qt macro is found, then the C++ source file
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``<base>.<source_extension>`` is expected to as well contain an include
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statement
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.. code-block:: c++
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#include <<base>.moc> // or
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#include "<base>.moc"
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The source file then will be compiled by the ``moc`` to the output file
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``<base>.moc``. A description of the complete output file path is in section
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`Output file location`_.
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The source will be ``moc`` compiled again if a file from the additional file
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dependencies changes.
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Including header moc files in sources
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"""""""""""""""""""""""""""""""""""""
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A source file can include the ``moc`` output file of a header
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``<header_base>.<header_extension>`` by using an include statement of
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the form
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.. code-block:: c++
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#include <moc_<header_base>.cpp> // or
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#include "moc_<header_base>.cpp"
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If the ``moc`` output file of a header is included by a source, it will
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be generated in a different location than if it was not included. This is
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described in the section `Output file location`_.
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Output file location
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^^^^^^^^^^^^^^^^^^^^
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Included moc output files
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"""""""""""""""""""""""""
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``moc`` output files that are included by a source file will be generated in
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- ``<AUTOGEN_BUILD_DIR>/include``
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for single configuration generators or in
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- ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>``
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for :prop_gbl:`multi configuration <GENERATOR_IS_MULTI_CONFIG>` generators.
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Where ``<AUTOGEN_BUILD_DIR>`` is the value of the target property
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:prop_tgt:`AUTOGEN_BUILD_DIR`.
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The include directory is automatically added to the target's
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:prop_tgt:`INCLUDE_DIRECTORIES`.
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Not included moc output files
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"""""""""""""""""""""""""""""
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``moc`` output files that are not included in a source file will be generated
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in
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- ``<AUTOGEN_BUILD_DIR>/<SOURCE_DIR_CHECKSUM>``
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for single configuration generators or in,
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- ``<AUTOGEN_BUILD_DIR>/include_<CONFIG>/<SOURCE_DIR_CHECKSUM>``
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for :prop_gbl:`multi configuration <GENERATOR_IS_MULTI_CONFIG>` generators.
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Where ``<SOURCE_DIR_CHECKSUM>`` is a checksum computed from the relative
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parent directory path of the ``moc`` input file. This scheme allows to have
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``moc`` input files with the same name in different directories.
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All not included ``moc`` output files will be included automatically by the
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CMake generated file
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- ``<AUTOGEN_BUILD_DIR>/mocs_compilation.cpp``,
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which is added to the target's sources.
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Qt version detection
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^^^^^^^^^^^^^^^^^^^^
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:prop_tgt:`AUTOMOC` enabled targets need to know the Qt major and minor
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version they're working with. The major version usually is provided by the
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``INTERFACE_QT_MAJOR_VERSION`` property of the ``Qt[45]Core`` library,
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that the target links to. To find the minor version, CMake builds a list of
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available Qt versions from
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- ``Qt5Core_VERSION_MAJOR`` and ``Qt5Core_VERSION_MINOR`` variables
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(usually set by ``find_package(Qt5...)``)
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- ``Qt5Core_VERSION_MAJOR`` and ``Qt5Core_VERSION_MINOR`` directory properties
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- ``QT_VERSION_MAJOR`` and ``QT_VERSION_MINOR`` variables
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(usually set by ``find_package(Qt4...)``)
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- ``QT_VERSION_MAJOR`` and ``QT_VERSION_MINOR`` directory properties
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in the context of the :command:`add_executable` or :command:`add_library` call.
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Assumed ``INTERFACE_QT_MAJOR_VERSION`` is a valid number, the first
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entry in the list with a matching major version is taken. If no matching major
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version was found, an error is generated.
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If ``INTERFACE_QT_MAJOR_VERSION`` is not a valid number, the first
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entry in the list is taken.
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A ``find_package(Qt[45]...)`` call sets the ``QT/Qt5Core_VERSION_MAJOR/MINOR``
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variables. If the call is in a different context than the
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:command:`add_executable` or :command:`add_library` call, e.g. in a function,
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then the version variables might not be available to the :prop_tgt:`AUTOMOC`
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enabled target.
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In that case the version variables can be forwarded from the
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`find_package(Qt[45]...)` calling context to the :command:`add_executable`
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or :command:`add_library` calling context as directory properties.
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The following Qt5 example demonstrates the procedure.
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.. code-block:: cmake
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function (add_qt5_client)
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find_package(Qt5 REQUIRED QUIET COMPONENTS Core Widgets)
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...
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set_property(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
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PROPERTY Qt5Core_VERSION_MAJOR "${Qt5Core_VERSION_MAJOR}")
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set_property(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
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PROPERTY Qt5Core_VERSION_MINOR "${Qt5Core_VERSION_MAJOR}")
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...
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endfunction ()
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...
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add_qt5_client()
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add_executable(myTarget main.cpp)
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target_link_libraries(myTarget Qt5::QtWidgets)
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set_property(TARGET myTarget PROPERTY AUTOMOC ON)
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Modifiers
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^^^^^^^^^
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:prop_tgt:`AUTOMOC_EXECUTABLE`:
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The ``moc`` executable will be detected automatically, but can be forced to
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a certain binary using the :prop_tgt:`AUTOMOC_EXECUTABLE` property.
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a certain binary using this target property.
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Additional command line options for ``moc`` can be set via the
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:prop_tgt:`AUTOMOC_MOC_OPTIONS` property.
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:prop_tgt:`AUTOMOC_MOC_OPTIONS`:
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Additional command line options for ``moc`` can be set in this target property.
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By enabling the :variable:`CMAKE_AUTOMOC_RELAXED_MODE` variable the
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rules for searching the files which will be processed by ``moc`` can be relaxed.
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See the documentation for this variable for more details.
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:prop_tgt:`AUTOMOC_MACRO_NAMES`:
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This list of Qt macro names can be extended to search for additional macros in
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headers and sources.
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The global property :prop_gbl:`AUTOGEN_TARGETS_FOLDER` can be used to group the
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automoc targets together in an IDE, e.g. in MSVS.
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:prop_tgt:`AUTOMOC_DEPEND_FILTERS`:
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``moc`` dependency file names can be extracted from headers or sources by
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defining file name filters in this target property.
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The global property :prop_gbl:`AUTOGEN_SOURCE_GROUP` can be used to group
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files generated by :prop_tgt:`AUTOMOC` together in an IDE, e.g. in MSVS.
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:prop_tgt:`AUTOMOC_COMPILER_PREDEFINES`:
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Compiler pre definitions for ``moc`` are written to the ``moc_predefs.h`` file.
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The generation of this file can be enabled or disabled in this target property.
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Additional macro names to search for can be added to
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:prop_tgt:`AUTOMOC_MACRO_NAMES`.
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:prop_sf:`SKIP_AUTOMOC`:
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Sources and headers can be excluded from :prop_tgt:`AUTOMOC` processing by
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setting this source file property.
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Additional ``moc`` dependency file names can be extracted from source code
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by using :prop_tgt:`AUTOMOC_DEPEND_FILTERS`.
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:prop_sf:`SKIP_AUTOGEN`:
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Source files can be excluded from :prop_tgt:`AUTOMOC`,
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:prop_tgt:`AUTOUIC` and :prop_tgt:`AUTORCC` processing by
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setting this source file property.
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Compiler pre definitions for ``moc`` are written to a ``moc_predefs.h`` file
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which is controlled by :prop_tgt:`AUTOMOC_COMPILER_PREDEFINES`.
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:prop_gbl:`AUTOGEN_SOURCE_GROUP`:
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This global property can be used to group files generated by
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:prop_tgt:`AUTOMOC` or :prop_tgt:`AUTORCC` together in an IDE, e.g. in MSVS.
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Source C++ files can be excluded from :prop_tgt:`AUTOMOC` processing by
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enabling :prop_sf:`SKIP_AUTOMOC` or the broader :prop_sf:`SKIP_AUTOGEN`.
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:prop_gbl:`AUTOGEN_TARGETS_FOLDER`:
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This global property can be used to group :prop_tgt:`AUTOMOC`,
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:prop_tgt:`AUTOUIC` and :prop_tgt:`AUTORCC` targets together in an IDE,
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e.g. in MSVS.
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The number of parallel ``moc`` processes to start can be modified by
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setting :prop_tgt:`AUTOGEN_PARALLEL`.
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:variable:`CMAKE_GLOBAL_AUTOGEN_TARGET`:
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A global ``autogen`` target, that depends on all :prop_tgt:`AUTOMOC` or
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:prop_tgt:`AUTOUIC` generated ``<ORIGIN>_autogen`` targets in the project,
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will be generated when this variable is ``ON``.
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A global ``autogen`` target that depends on all :prop_tgt:`AUTOMOC` generated
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``<ORIGIN>_autogen`` targets in the project can be generated by enabling
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:variable:`CMAKE_GLOBAL_AUTOGEN_TARGET`.
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:prop_tgt:`AUTOGEN_PARALLEL`:
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This target property controls the number of ``moc`` or ``uic`` processes to
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start in parallel during builds.
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See the :manual:`cmake-qt(7)` manual for more information on using CMake
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with Qt.
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