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Document QT_ANDROID_MULTI_ABI_FORWARD_VARS CMake variable

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Add documentation for the QT_ANDROID_MULTI_ABI_FORWARD_VARS CMake
variable.

Task-number: QTBUG-107893
Change-Id: Ia8dfd14a89d043c4f967464646388f57c96f911a
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
(cherry picked from commit 050b849c9664ba15cbe4a6ec176fec217f276094)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Alexey Edelev 2022-11-17 17:08:11 +01:00 committed by Qt Cherry-pick Bot
parent 5246393d91
commit c9d886f1c2
1 changed files with 81 additions and 0 deletions
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src/corelib/doc/src/cmake/cmake-configure-variables.qdoc
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@ -79,6 +79,87 @@ 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-multi-abi-forward-vars
\ingroup cmake-variables-qtcore
\title QT_ANDROID_MULTI_ABI_FORWARD_VARS
\target cmake-variable-QT_ANDROID_MULTI_ABI_FORWARD_VARS
\summary {Allows to share CMake variables in multi-ABI builds}
\cmakevariablesince 6.4.2
\preliminarycmakevariable
\cmakevariableandroidonly
The \c{QT_ANDROID_MULTI_ABI_FORWARD_VARS} variable allows specifying the list of
CMake variables that need to be forwarded from the main ABI project to
ABI-specific subprojects. Due to the specifics of the Multi-ABI project build
process, there is no generic way to forward the CMake cache variables
that are specified either in the command line or in another similar way.
A typical use case for the variable is propagating CMake cache variables
specified in the command line. For example, a project has two variables
\c{PROJECT_WIDE_VARIABLE1} and \c{PROJECT_WIDE_VARIABLE2} that affect the
project configuration:
\badcode
cmake_minimum_required(VERSION 3.18)
project(MyProject LANGUAGES CXX)
find_package(Qt6 REQUIRED COMPONENTS Core)
qt_add_executable(MyApp main.cpp)
if(PROJECT_WIDE_VARIABLE1)
target_sources(MyApp PRIVATE sourcefile1.cpp)
endif()
if(PROJECT_WIDE_VARIABLE2)
target_sources(MyApp PRIVATE sourcefile2.cpp)
endif()
\endcode
The above contents of \c{CMakeLists.txt} enable you to control how
\c{MyApp} is built by setting the corresponding CMake variables from the
command line:
\badcode
qt-cmake -S<source directory> -B<build directory> \
-DPROJECT_WIDE_VARIABLE1=ON \
-DPROJECT_WIDE_VARIABLE2=ON \
-DQT_ANDROID_MULTI_ABI_FORWARD_VARS="PROJECT_WIDE_VARIABLE1;PROJECT_WIDE_VARIABLE2"
\endcode
When configuring the application for desktop, \c{PROJECT_WIDE_VARIABLE1} and
\c{PROJECT_WIDE_VARIABLE2} are visible in CMake listings and scripts as global
cache variables. This doesn't work for Android Multi-ABI builds because
ABI-specific subprojects do not inherit the cache variables from the main-ABI
project. This issue can be solved by passing the list of required variables to
the \c{QT_ANDROID_MULTI_ABI_FORWARD_VARS} variable, so both
\c{PROJECT_WIDE_VARIABLE1} and \c{PROJECT_WIDE_VARIABLE2} values will be
propagated to the ABI-specific builds.
The variable can be also defined in the project's CMakeLists.txt:
\badcode
...
qt_add_executable(MyApp main.cpp)
...
if(ANDROID)
set(QT_ANDROID_MULTI_ABI_FORWARD_VARS "PROJECT_WIDE_VARIABLE1;PROJECT_WIDE_VARIABLE2")
endif()
...
\endcode
Setting the variable in this way allows you to have a predefined set of
variables that will always be forwarded to abi-specific projects.
\note The forwarding is done in the target finalizer, which is implicitly
called when \l{qt6_add_executable}{qt_add_executable()} is used. The
finalization occurs automatically when using CMake 3.19 or later.
\sa {qt6_finalize_target}{qt_finalize_target()},
{qt6_add_executable}{qt_add_executable()}
*/
/*!
\page cmake-variable-qt-android-build-all-abis.html
\ingroup cmake-variables-qtcore