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* Revert "CMake: Warn if cmake_minimum_required has an unsupported low version"Alexandru Croitor2021-10-041-58/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 657525965b86cfa135bb5a814a537443163acb14. The change relied on reading the last value of the CMAKE_MINIMUM_REQUIRED_VERSION variable before one of the Qt packages is found to use it for the version check. Even if a user project has a cmake_minimum_required() right at the beginning of the project with a supported version specified, the first project() call which loads a CMake toolchain file could contain another cmake_minimum_required() call with a lower (unsupported) version and that version would be used for the check, failing the project configuration. The Android NDK ships such a toolchain file, which requires version '3.6'. Thus, relying on the last value of CMAKE_MINIMUM_REQUIRED_VERSION is not robust enough. Pick-to: 6.2 Task-number: QTBUG-95018 Task-number: QTBUG-95832 Change-Id: Iff3cb0a46e6e878569dce9c5fe915a714a034904 Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
* CMake: Warn if cmake_minimum_required has an unsupported low versionAlexandru Croitor2021-10-011-0/+58
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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 6518bcc167d47e1c27d082c21551b9a838b04e5d 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>
* CMake: Enforce minimum CMake version in user projectsAlexandru Croitor2021-08-041-0/+69
This change introduces new behavior to error out when configuring user projects if the CMake version used is too old for Qt to work with. The main motivator is the requirement of new CMake features to ensure object libraries are placed in the proper place on the link line in static builds. The minimum CMake version is computed based on whether Qt was configured as shared or static libraries. At the moment the required versions for building and using Qt are the same. The minimum versions are defined in qtbase/.cmake.conf in the following variables QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_BUILDING_QT_SHARED QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_BUILDING_QT_STATIC QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_SHARED QT_SUPPORTED_MIN_CMAKE_VERSION_FOR_USING_QT_STATIC Qt Packagers can disable the version check when configuring Qt by setting QT_FORCE_MIN_CMAKE_VERSION_FOR_BUILDING_QT and QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT. In this case it is the packagers responsibility to ensure such a Qt works correctly with the specified CMake version. User projects can also set QT_FORCE_MIN_CMAKE_VERSION_FOR_USING_QT to disable the version check. Then it's the project's developer responsibility to ensure such a Qt works correctly. No official support is provided for these cases. Implementation notes. The versions required to build Qt are stored in QtBuildInternalsExtra.cmake whereas the versions required to use Qt are stored in a new QtConfigExtras.cmake. Also the policy range variables stored in QtBuildInternalsExtra.cmake are now regular variables instead of cache variables, to properly allow overrides per-repository. Some renaming of functions and variables was done for a bit more clarity and easier grep-ability. Pick-to: 6.2 Task-number: QTBUG-95018 Change-Id: I4279f2e10b6d3977319237ba21e2f4ed676aa48b Reviewed-by: Alexey Edelev <alexey.edelev@qt.io> Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>