657525965b
Qt6Config.cmake calls cmake_minimum_required to ensure a recent enough
CMake version is used in projects.
That call does not set policies in the calling subdirectory scope,
because find_package introduces a new policy scope.
If a project using Qt has a 'cmake_minimum_required(VERSION 3.1)'
call and is configured with a recent CMake, many policies will
still be set to OLD.
One such policy is CMP0071 (Run AUTOMOC on GENERATED files). The
policy value is queried at generation time rather than at target
definition time, which means we can't influence the policy value
(e.g. inside the implementation of qt_add_executable for example)
The inability to influence the policy value for targets created by our
own CMake functions is unfortunate and can lead to issues (in the case
of the above policy to compilation / linker issues).
Record the version of the last cmake_minimum_required call before
the Qt packages are found and error out if the version is lower than
the minimum supported one.
A project can reduce the error into a warning by specifying a
-DQT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED=3.xyz
option when configuring the project.
If the option is used and build issues arise, no official support is
given.
All the CMake example projects shipped with Qt specify a minimum
version of 3.16 already (which is the minimum for shared Qt builds),
so it shouldn't be an issue to require that in other user projects as
well.
Implementation wise, we follow the existing pattern to record
what the minimum and computed versions for static and shared Qt
builds are at qtbase configure time.
These are then checked before the Qt6 or QtFoo packages are
find_package'd.
Amends 6518bcc167
Pick-to: 6.2
Task-number: QTBUG-95018
Task-number: QTBUG-95832
Change-Id: I1a1d06d82f566c92192a699045127943604c8353
Reviewed-by: Craig Scott <craig.scott@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
128 lines
6.2 KiB
CMake
128 lines
6.2 KiB
CMake
function(__qt_internal_get_supported_min_cmake_version_for_using_qt out_var)
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# This is recorded in Qt6ConfigExtras.cmake
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set(supported_version "${QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT}")
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set(${out_var} "${supported_version}" PARENT_SCOPE)
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endfunction()
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function(__qt_internal_get_supported_min_cmake_version_for_using_qt_in_cmake_min_required out_var)
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# This is recorded in Qt6ConfigExtras.cmake
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set(supported_version "${QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED}")
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set(${out_var} "${supported_version}" PARENT_SCOPE)
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endfunction()
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function(__qt_internal_get_computed_min_cmake_version_for_using_qt out_var)
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# Allow override when configuring user project.
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if(QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT)
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set(computed_min_version "${QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT}")
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# Set in QtConfigExtras.cmake.
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elseif(QT_COMPUTED_MIN_CMAKE_VERSION_FOR_USING_QT)
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set(computed_min_version "${QT_COMPUTED_MIN_CMAKE_VERSION_FOR_USING_QT}")
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else()
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message(FATAL_ERROR
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"Qt Developer error: Can't compute the minimum CMake version required to use this Qt.")
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endif()
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set(${out_var} "${computed_min_version}" PARENT_SCOPE)
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endfunction()
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function(__qt_internal_get_computed_min_cmake_version_for_using_qt_in_cmake_min_required out_var)
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# Allow override when configuring user project.
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if(QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED)
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set(computed_min_version "${QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED}")
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# Set in QtConfigExtras.cmake.
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elseif(QT_COMPUTED_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED)
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set(computed_min_version
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"${QT_COMPUTED_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED}")
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else()
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message(FATAL_ERROR
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"Qt Developer error: Can't compute the version that should appear in cmake_minimum_required to use this Qt.")
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endif()
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set(${out_var} "${computed_min_version}" PARENT_SCOPE)
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endfunction()
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function(__qt_internal_warn_if_min_cmake_version_not_met)
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__qt_internal_get_supported_min_cmake_version_for_using_qt(min_supported_version)
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__qt_internal_get_computed_min_cmake_version_for_using_qt(computed_min_version)
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if(NOT min_supported_version STREQUAL computed_min_version
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AND computed_min_version VERSION_LESS min_supported_version)
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message(WARNING
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"The minimum required CMake version to use Qt is: '${min_supported_version}'. "
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"You have explicitly chosen to require a lower minimum CMake version: '${computed_min_version}'. "
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"Using Qt with this CMake version is not officially supported. Use at your own risk."
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)
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endif()
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endfunction()
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function(__qt_internal_warn_if_project_min_cmake_version_is_not_met)
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__qt_internal_get_supported_min_cmake_version_for_using_qt_in_cmake_min_required(
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min_supported_version)
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__qt_internal_get_computed_min_cmake_version_for_using_qt_in_cmake_min_required(
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computed_min_version)
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if(computed_min_version VERSION_LESS min_supported_version)
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message(WARNING
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"To use this Qt, the minimum CMake version that should appear in the project's "
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"cmake_minimum_required() call should be: '${min_supported_version}'. "
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"You have explicitly chosen to require a lower version: '${computed_min_version}'. "
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"Using Qt with this version is not officially supported. Use at your own risk."
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)
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endif()
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endfunction()
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function(__qt_internal_require_suitable_cmake_version_for_using_qt)
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# Skip the public project check if we're building a Qt repo because it's too early to do
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# it at find_package(Qt6) time.
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# Instead, a separate check is done in qt_build_repo_begin.
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# We detect a Qt repo by the presence of the QT_REPO_MODULE_VERSION variable set in .cmake.conf
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# of each repo.
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if(QT_REPO_MODULE_VERSION)
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return()
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endif()
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# Only do the setup once per directory scope, because Qt6 is a dependency for many packages,
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# and a recursive call will show the warning multiple times.
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if(__qt_internal_set_up_cmake_minimum_required_version_already_done)
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return()
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endif()
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set(__qt_internal_set_up_cmake_minimum_required_version_already_done TRUE PARENT_SCOPE)
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# Check the overall minimum required CMake version when consuming any Qt CMake package.
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__qt_internal_warn_if_min_cmake_version_not_met()
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__qt_internal_get_computed_min_cmake_version_for_using_qt(computed_min_version)
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if(CMAKE_VERSION VERSION_LESS computed_min_version)
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set(major_minor "${CMAKE_MAJOR_VERSION}.${CMAKE_MINOR_VERSION}")
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message(FATAL_ERROR
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"CMake ${computed_min_version} or higher is required to use Qt. "
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"You are running version ${CMAKE_VERSION} "
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"Qt requires newer CMake features to work correctly. You can lower the minimum "
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"required version by passing "
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"-DQT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT=${major_minor} when configuring the "
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"project. Using Qt with this CMake version is not officially supported. "
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"Use at your own risk.")
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endif()
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# Check that the project has a supported version specified in the last cmake_minimum_required
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# call before the Qt6 package was found.
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__qt_internal_warn_if_project_min_cmake_version_is_not_met()
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__qt_internal_get_computed_min_cmake_version_for_using_qt_in_cmake_min_required(
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computed_min_version)
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if(_qt_project_last_cmake_minimum_required_version VERSION_LESS computed_min_version)
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message(FATAL_ERROR
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"The last cmake_minimum_required() call before the Qt package was found had the "
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"following version specified: '${_qt_project_last_cmake_minimum_required_version}' but "
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"it needs to be ${computed_min_version} or higher to use Qt. "
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"You can reduce the error into a warning by passing "
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"-DQT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT_IN_CMAKE_MIN_REQUIRED=${_qt_project_last_cmake_minimum_required_version} "
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"when configuring the project, but you do so at your own risk (it is not an officially "
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"supported way of building Qt projects)."
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)
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endif()
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endfunction()
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