Doc: Add partial documentation for CMake API (tech preview)

There are still other parts of the CMake API that are not yet
documented. This change only addresses qt_add_executable() and the
Android-related commands it uses.

Fixes: QTBUG-88839
Task-number: QTBUG-84482
Pick-to: 6.0
Change-Id: I761b5ce908d1f62284baabe2d414cd37a0efe83d
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Assam Boudjelthia <assam.boudjelthia@qt.io>

4 files changed, 601 insertions, 1 deletions

diff --git a/src/corelib/doc/snippets/cmake-macros/examples.cmake b/src/corelib/doc/snippets/cmake-macros/examples.cmake
index 820b28cf88..685b29db01 100644
--- a/src/corelib/doc/snippets/cmake-macros/examples.cmake
+++ b/src/corelib/doc/snippets/cmake-macros/examples.cmake
@@ -73,3 +73,18 @@ qt_import_plugins(myapp
     EXCLUDE_BY_TYPE sqldrivers
 )
 #! [qt_import_plugins]
+
+#! [qt_add_executable_simple]
+qt_add_executable(simpleapp main.cpp)
+#! [qt_add_executable_simple]
+
+#! [qt_add_executable_deferred]
+qt_add_executable(complexapp MANUAL_FINALIZATION complex.cpp)
+set_target_properties(complexapp PROPERTIES OUTPUT_NAME Complexify)
+qt_finalize_target(complexapp)
+#! [qt_add_executable_deferred]
+
+#! [qt_android_deploy_basic]
+qt_android_generate_deployment_settings(myapp)
+qt_android_add_apk_target(myapp)
+#! [qt_android_deploy_basic]
diff --git a/src/corelib/doc/src/cmake-macros.qdoc b/src/corelib/doc/src/cmake-macros.qdoc
index a86913fed9..af3ab324b9 100644
--- a/src/corelib/doc/src/cmake-macros.qdoc
+++ b/src/corelib/doc/src/cmake-macros.qdoc
@@ -241,7 +241,7 @@ when scanning the source files with \c{moc}.
 \title qt_import_plugins
 \target qt6_import_plugins
 
-\brief Specifies a custom set of plugins to import for a static Qt build
+\brief Specifies a custom set of plugins to import for a static Qt build.
 
 \section1 Synopsis
 
@@ -304,3 +304,284 @@ In the snippet above, the following occurs with the executable \c myapp:
 \li All \c sqldrivers plugins are excluded from automatic importing.
 \endlist
 */
+
+/*!
+\page qt_add_executable.html
+\ingroup cmake-macros-qtcore
+
+\title qt_add_executable
+\target qt6_add_executable
+
+\brief Creates and finalizes an application target of a platform-specific type.
+
+\preliminarycmakecommand
+
+\section1 Synopsis
+
+\badcode
+qt_add_executable(target
+                  [WIN32] [MACOSX_BUNDLE]
+                  [MANUAL_FINALIZATION]
+                  sources...)
+
+qt6_add_executable(target
+                   [WIN32] [MACOSX_BUNDLE]
+                   [MANUAL_FINALIZATION]
+                   sources...)
+\endcode
+
+\section1 Description
+
+This command performs the following tasks:
+
+\list
+\li Create a CMake target of the appropriate type for the target platform.
+\li Link the target to the \c{Qt::Core} library.
+\li Handle finalization of the CMake target.
+\endlist
+
+\section2 Target Creation
+
+On all platforms except Android, an executable target will be created.
+All arguments will be passed through to the standard CMake \c{add_executable()}
+command, except \c{MANUAL_FINALIZATION} (if present). On Android, a \c{MODULE}
+library will be created and any \c{WIN32} or \c{MACOSX_BUNDLE} options will be
+ignored. Some target properties will also be set for Android:
+
+\list
+\li The \c{SUFFIX} target property will be set to give the library file name an
+    architecture-specific suffix.
+\li Various \c{<lang>_VISIBILITY_PRESET} target properties will be set to
+    \c{default} to ensure that the \c{main()} function is visible in the
+    resultant binary.
+\endlist
+
+\section2 Linking Qt::Core
+
+Since all Qt applications need to link to the \c{Qt::Core} library, this is done
+for you as a convenience.
+
+\section2 Finalization
+
+After a target is created, further processing or \e{finalization} steps are
+commonly needed. The steps to perform depend on the platform and on various
+properties of the target. The finalization processing is implemented by the
+\l{qt6_finalize_executable}{qt_finalize_executable()} command.
+
+Finalization can occur either as part of this call or be deferred to sometime
+after this command returns. When using CMake 3.19 or later, finalization is
+automatically deferred to the end of the current directory scope. This gives the
+caller an opportunity to modify properties of the created target before it is
+finalized. When using CMake versions earlier than 3.19, automatic deferral isn't
+supported. In that case, finalization is performed immediately before this
+command returns.
+
+Regardless of the CMake version, the \c{MANUAL_FINALIZATION} keyword can be given to
+indicate that you will explicitly call \l{qt6_finalize_executable}{qt_finalize_executable()}
+yourself instead at some later time. In general, \c MANUAL_FINALIZATION should
+not be needed unless the project has to support CMake 3.18 or earlier.
+
+\sa {qt6_finalize_executable}{qt_finalize_executable()}
+
+\section1 Examples
+
+In the following simple case, finalization is handled automatically. If using a
+CMake version earlier than 3.19, finalization will be performed immediately as
+part of the call. When using CMake 3.19 or later, finalization will occur at the
+end of the current directory scope.
+
+\snippet cmake-macros/examples.cmake qt_add_executable_simple
+
+The following example shows a scenario where finalization must be deferred.
+The \c OUTPUT_NAME target property affects deployment settings on Android, but
+those settings are written out as part of finalizing the target. In order to
+support using CMake versions earlier than 3.19, we take over responsibility
+for finalizing the target by adding the \c{MANUAL_FINALIZATION} keyword.
+
+\snippet cmake-macros/examples.cmake qt_add_executable_deferred
+*/
+
+/*!
+\page qt_finalize_executable.html
+\ingroup cmake-macros-qtcore
+
+\title qt_finalize_executable
+\target qt6_finalize_executable
+
+\brief Handles various common platform-specific tasks associated with Qt targets.
+
+\preliminarycmakecommand
+
+\section1 Synopsis
+
+\badcode
+qt_finalize_executable(target)
+
+qt6_finalize_executable(target)
+\endcode
+
+\section1 Description
+
+After a target is created, further processing or \e{finalization} steps are
+commonly needed. The steps to perform depend on the platform and on various
+properties of the target. This command implements the following, as appropriate
+for the platform and target provided:
+
+\list
+\li When targeting Android, generate a deployment settings file for the target.
+\li Create a build target for generating an APK if building for Android.
+\endlist
+
+This command is ordinarily invoked as part of a call to
+\l{qt6_add_executable}{qt_add_executable()}. The timing of when that call takes
+place and when it might need to be called explicitly by a project is discussed
+in the documentation of that command.
+*/
+
+/*!
+\page qt_android_apply_arch_suffix.html
+\ingroup cmake-macros-qtcore
+
+\title qt_android_apply_arch_suffix
+\target qt6_android_apply_arch_suffix
+
+\brief Configures the target binary's name to include an architecture-specific suffix.
+
+\preliminarycmakecommand
+\cmakecommandandroidonly
+
+\section1 Synopsis
+
+\badcode
+qt_android_apply_arch_suffix(target)
+
+qt6_android_apply_arch_suffix(target)
+\endcode
+
+\section1 Description
+
+The CMake \c{SUFFIX} target property controls the suffix used on the file name
+of the target's built binary. This command is a convenience for setting that
+property to an architecture-specific value. This is useful when installing
+multiple builds for different Android architectures into the same install
+location, as it prevents the libraries for different architectures from
+overwriting each other.
+*/
+
+/*!
+\page qt_android_generate_deployment_settings.html
+\ingroup cmake-macros-qtcore
+
+\title qt_android_generate_deployment_settings
+\target qt6_android_generate_deployment_settings
+
+\brief Generates the deployment settings file needed by androiddeployqt.
+
+\preliminarycmakecommand
+\cmakecommandandroidonly
+
+\section1 Synopsis
+
+\badcode
+qt_android_generate_deployment_settings(target)
+
+qt6_android_generate_deployment_settings(target)
+\endcode
+
+\section1 Description
+
+The \c{androiddeployqt} tool expects a deployment settings file as input. This
+command reads CMake variables and properties of the \c{target} to generate such
+a file in the target's binary directory. Upon return, the full path to this file
+is available in the target's \c{QT_ANDROID_DEPLOYMENT_SETTINGS_FILE} property.
+
+\section2 CMake Variables
+
+A number of variables are used while generating the deployment settings file.
+Some are provided by Qt, others by CMake or the Android NDK.
+
+\list
+\li \l{cmake-variable-ANDROID_NDK_HOST_SYSTEM_NAME}{ANDROID_NDK_HOST_SYSTEM_NAME}
+\li \l{cmake-variable-ANDROID_SDK_ROOT}{ANDROID_SDK_ROOT}
+\li \c{CMAKE_ANDROID_ARCH_ABI}
+\li \c{CMAKE_ANDROID_NDK}
+\li \c{CMAKE_SYSROOT}
+\li \l{cmake-variable-QT_ANDROID_APPLICATION_ARGUMENTS}{QT_ANDROID_APPLICATION_ARGUMENTS}
+\li \l{cmake-variable-QT_HOST_PATH}{QT_HOST_PATH}
+\endlist
+
+\section2 Target Properties
+
+The properties below will be read from the specified \c{target}. Note that this
+command is called as part of target finalization (see
+\l{qt6_finalize_executable}{qt_finalize_executable()}). If you are using
+\l{qt6_add_executable}{qt_add_executable()} to create the target and you need to
+modify some of these target properties, you need to ensure that target
+finalization is deferred. See \l{qt6_add_executable}{qt_add_executable()} for
+how to accomplish this.
+
+\list
+\li \l{cmake-target-property-QT_ANDROID_DEPLOYMENT_DEPENDENCIES}{QT_ANDROID_DEPLOYMENT_DEPENDENCIES}
+\li \l{cmake-target-property-QT_ANDROID_EXTRA_LIBS}{QT_ANDROID_EXTRA_LIBS}
+\li \l{cmake-target-property-QT_ANDROID_EXTRA_PLUGINS}{QT_ANDROID_EXTRA_PLUGINS}
+\li \l{cmake-target-property-QT_ANDROID_PACKAGE_SOURCE_DIR}{QT_ANDROID_PACKAGE_SOURCE_DIR}
+\li \l{cmake-target-property-QT_QML_IMPORT_PATH}{QT_QML_IMPORT_PATH}
+\li \l{cmake-target-property-QT_QML_ROOT_PATH}{QT_QML_ROOT_PATH}
+\endlist
+
+Upon return, the \c{QT_ANDROID_DEPLOYMENT_SETTINGS_FILE} target property will
+contain the location of the generated deployment settings file.
+
+\sa {qt6_android_add_apk_target}{qt_android_add_apk_target()},
+    {qt6_finalize_executable}{qt_finalize_executable()}
+
+\section1 Example
+
+\snippet cmake-macros/examples.cmake qt_android_deploy_basic
+*/
+
+/*!
+\page qt_android_add_apk_target.html
+\ingroup cmake-macros-qtcore
+
+\title qt_android_add_apk_target
+\target qt6_android_add_apk_target
+
+\brief Defines a build target that runs androiddeployqt to produce an APK.
+
+\preliminarycmakecommand
+\cmakecommandandroidonly
+
+\section1 Synopsis
+
+\badcode
+qt_android_add_apk_target(target)
+
+qt6_android_add_apk_target(target)
+\endcode
+
+\section1 Description
+
+The \c{<target>_make_apk} custom target created by this command takes an Android
+deployment settings file and generates an APK by running \c{androiddeployqt}.
+The location of the settings file is taken from the \c{target}'s
+\c{QT_ANDROID_DEPLOYMENT_SETTINGS_FILE} property. This file is typically created by
+\l{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}.
+The \c{.apk} file will be generated in an \c{android-build} subdirectory below
+the CMake build directory of the \c{target}.
+
+The \c{<target>_make_apk} target will be automatically added as a dependency of
+the \c{apk} build target, which will be created if it doesn't already exist.
+This can be disabled by setting the \c{QT_NO_GLOBAL_APK_TARGET} variable to true.
+
+\sa {qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()},
+    {qt6_finalize_executable}{qt_finalize_executable()}
+
+\section1 Example
+
+\snippet cmake-macros/examples.cmake qt_android_deploy_basic
+
+The above commands define the build targets \c{myapp_make_apk} and \c{apk},
+which can be used to generate just the \c{myapp} APK or all APKs in the project
+respectively.
+*/
diff --git a/src/corelib/doc/src/cmake-properties.qdoc b/src/corelib/doc/src/cmake-properties.qdoc
new file mode 100644
index 0000000000..0a24fcba78
--- /dev/null
+++ b/src/corelib/doc/src/cmake-properties.qdoc
@@ -0,0 +1,204 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+\page cmake-target-property-QT_ANDROID_DEPLOYMENT_DEPENDENCIES.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_ANDROID_DEPLOYMENT_DEPENDENCIES
+\target cmake-target-property-QT_ANDROID_DEPLOYMENT_DEPENDENCIES
+
+\brief Overrides the Qt dependencies added to the target's deployment.
+
+\preliminarycmakeproperty
+\cmakepropertyandroidonly
+
+By default, \l androiddeployqt will detect the dependencies of your
+application. However, since run-time usage of plugins cannot be detected,
+there could be false positives, as your application might depend on any
+plugin that is a potential dependency. If you want to minimize the size of
+your \c APK, it's possible to override the automatic detection using this
+property. This should contain a list of all Qt files which need to be
+included, with paths relative to the Qt install root.
+
+\note Only the Qt files specified with this variable are included. Failing
+to include all the correct files can result in crashes. It's also important
+to make sure the files are listed in the correct loading order. This variable
+provides a way to override the automatic detection entirely, so if a library
+is listed before its dependencies, it will fail to load on some devices.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_ANDROID_EXTRA_LIBS.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_ANDROID_EXTRA_LIBS
+\target cmake-target-property-QT_ANDROID_EXTRA_LIBS
+
+\brief Extra libraries to deploy with the target.
+
+\preliminarycmakeproperty
+\cmakepropertyandroidonly
+
+A list of external libraries that will be copied into your application's
+\c libs folder and loaded on start-up. This can be used, for instance,
+to enable OpenSSL in your application. For more information, see
+\l{Adding OpenSSL Support for Android}.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_ANDROID_EXTRA_PLUGINS.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_ANDROID_EXTRA_PLUGINS
+\target cmake-target-property-QT_ANDROID_EXTRA_PLUGINS
+
+\brief Extra Qt plugins to deploy with the target.
+
+\preliminarycmakeproperty
+\cmakepropertyandroidonly
+
+Specifies a path to C++ plugins or resources that your application has to bundle
+but that cannot be delivered through the assets system, such as QML plugins.
+With this variable, \l androiddeployqt will make sure everything is packaged
+and deployed properly.
+
+\c QT_ANDROID_EXTRA_PLUGINS must point to the directory where the extra plugin(s)
+are built. In addition, the build directory structure must follow a naming
+convention similar to Qt plugins, that is, \e {plugins/<plugin name>}.
+\c QT_ANDROID_EXTRA_PLUGINS should point to the \e {plugins} part of that path.
+
+The plugins libraries should have the name format
+\e {libplugins_<type>_<name>_<abi>.so}. This will ensure that the correct name
+mangling is applied to the plugin library.
+\omit
+TODO: Not yet documented, API still under review - see QTBUG-88763
+See the \l{qt6_add_plugin}{qt_add_plugin()} command for the easiest way to achieve
+that.
+\endomit
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_ANDROID_PACKAGE_SOURCE_DIR.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_ANDROID_PACKAGE_SOURCE_DIR
+\target cmake-target-property-QT_ANDROID_PACKAGE_SOURCE_DIR
+
+\brief Path to a custom Android package template.
+
+\preliminarycmakeproperty
+\cmakepropertyandroidonly
+
+Specifies the path for a custom Android package template. The Android package
+template contains:
+\list
+    \li AndroidManifest.xml file
+    \li build.gradle file and other Gradle scripts
+    \li res/values/libs.xml file
+\endlist
+
+The path specified by this variable can contain custom Java classes under
+\c src directory. By default, the \l androiddeployqt tool copies the
+application template from the Qt for Android installation path into your
+project's build directory, then it copies the contents of the path specified
+by this variable on top of that, overwriting any existing files. For
+instance, you can make a custom \c {AndroidManifest.xml} for your application,
+then place this directly into the directory specified by this variable.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_QML_ROOT_PATH.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_QML_ROOT_PATH
+\target cmake-target-property-QT_QML_ROOT_PATH
+
+\brief Overrides the location of the application's qml directory.
+
+\preliminarycmakeproperty
+
+This property is currently only used when generating a deployment settings file
+for Android. If the property is set, it specifies the path to the application's
+\c{qml} directory. If it is not set, the \c{SOURCE_DIR} property of the target
+will be used instead.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_QML_IMPORT_PATH.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_QML_IMPORT_PATH
+\target cmake-target-property-QT_QML_IMPORT_PATH
+
+\brief Specifies a list of directories to search for QML imports.
+
+\preliminarycmakeproperty
+
+This property is currently only used when generating a deployment settings file
+for Android. It typically contains just the path to Qt's \c{qml} directory, but
+it can be a list that contains other locations to be searched as well.
+For application-specific QML imports, use
+\l{cmake-target-property-QT_QML_ROOT_PATH}{QT_QML_ROOT_PATH} instead.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-target-property-QT_ANDROID_DEPLOYMENT_SETTINGS_FILE.html
+\ingroup cmake-properties-qtcore
+\ingroup cmake-target-properties-qtcore
+
+\title QT_ANDROID_DEPLOYMENT_SETTINGS_FILE
+\target cmake-target-property-QT_ANDROID_DEPLOYMENT_SETTINGS_FILE
+
+\brief Specifies the location of a target's generated deployment settings file.
+
+\preliminarycmakeproperty
+\cmakepropertyandroidonly
+
+This property will be set by
+\l{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}.
+Projects should not try to set this property themselves, as it will be ignored
+and overwritten by that command.
+*/
diff --git a/src/corelib/doc/src/cmake-variables.qdoc b/src/corelib/doc/src/cmake-variables.qdoc
new file mode 100644
index 0000000000..d3f73ab918
--- /dev/null
+++ b/src/corelib/doc/src/cmake-variables.qdoc
@@ -0,0 +1,100 @@
+/****************************************************************************
+**
+** Copyright (C) 2021 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the documentation of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:FDL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Free Documentation License Usage
+** Alternatively, this file may be used under the terms of the GNU Free
+** Documentation License version 1.3 as published by the Free Software
+** Foundation and appearing in the file included in the packaging of
+** this file. Please review the following information to ensure
+** the GNU Free Documentation License version 1.3 requirements
+** will be met: https://www.gnu.org/licenses/fdl-1.3.html.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+/*!
+\page cmake-variable-ANDROID_NDK_HOST_SYSTEM_NAME.html
+\ingroup cmake-variables
+\ingroup cmake-variables-qtcore
+
+\title ANDROID_NDK_HOST_SYSTEM_NAME
+\target cmake-variable-ANDROID_NDK_HOST_SYSTEM_NAME
+
+\brief Android-specific architecture of the host system.
+
+\preliminarycmakevariable
+\cmakevariableandroidonly
+
+This is normally set by the Android NDK toolchain file. It is written out as
+part of the deployment settings for a target.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-variable-ANDROID_SDK_ROOT.html
+\ingroup cmake-variables
+\ingroup cmake-variables-qtcore
+
+\title ANDROID_SDK_ROOT
+\target cmake-variable-ANDROID_SDK_ROOT
+
+\brief Location of the Android SDK.
+
+\preliminarycmakevariable
+\cmakevariableandroidonly
+
+This specifies the location of the Android SDK when building for the Android platform.
+It is written out as part of the deployment settings for a target.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}.
+*/
+
+/*!
+\page cmake-variable-QT_ANDROID_APPLICATION_ARGUMENTS.html
+\ingroup cmake-variables
+\ingroup cmake-variables-qtcore
+
+\title QT_ANDROID_APPLICATION_ARGUMENTS
+\target cmake-variable-QT_ANDROID_APPLICATION_ARGUMENTS
+
+\brief List of arguments to pass to Android applications.
+
+\preliminarycmakevariable
+\cmakevariableandroidonly
+
+This contains a list of arguments to be passed to Android applications. It is written
+out as part of the deployment settings for a target.
+
+\sa{qt6_android_generate_deployment_settings}{qt_android_generate_deployment_settings()}
+*/
+
+/*!
+\page cmake-variable-QT_HOST_PATH.html
+\ingroup cmake-variables
+\ingroup cmake-variables-qtcore
+
+\title QT_HOST_PATH
+\target cmake-variable-QT_HOST_PATH
+
+\brief Location of the host Qt installation when cross-compiling.
+
+\preliminarycmakevariable
+
+When cross-compiling, this must be set to the install location of Qt for the host
+platform. It is used to locate tools to be run on the host (\l{moc}, \l{rcc},
+\l{androiddeployqt}, and so on).
+*/