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qt5base-lts/cmake/QtCMakeVersionHelpers.cmake

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CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
# Returns the minimum supported CMake version required to build Qt as originally advertised by Qt.
function(qt_internal_get_qt_supported_minimum_cmake_version out_var)
# QT_MIN_SUPPORTED_CMAKE_VERSION is set either in .cmake.conf or in QtBuildInternalsExtras.cmake
# when building a child repo.
set(supported_version "${QT_MIN_SUPPORTED_CMAKE_VERSION}")
set(${out_var} "${supported_version}" PARENT_SCOPE)
endfunction()
# Returns the computed minimum supported CMake version required to build Qt.
function(qt_internal_get_computed_minimum_cmake_version out_var)
qt_internal_get_qt_supported_minimum_cmake_version(min_supported_version)
set(computed_min_version "${min_supported_version}")
# Set in QtBuildInternalsExtras.cmake.
if(QT_COMPUTED_MIN_CMAKE_VERSION)
set(computed_min_version "${QT_COMPUTED_MIN_CMAKE_VERSION}")
endif()
# An explicit override for those that take it upon themselves to fix the build system
# when using a CMake version lower than the one officially supported.
# Also useful for build testing locally with different minimum versions to observe different
# policy behaviors.
if(QT_FORCE_MIN_CMAKE_VERSION)
set(computed_min_version "${QT_FORCE_MIN_CMAKE_VERSION}")
endif()
set(${out_var} "${computed_min_version}" PARENT_SCOPE)
endfunction()
CMake: Enable NEW policies by CMake version with a global default When a CMake release introduces a new policy that affects most Qt modules, it may be appropriate to make each module aware of that newer CMake version and use the NEW policy without raising the minimum CMake version requirement. To reduce the churn associated with making that change across all Qt modules individually, this change allows it to be updated in a central place (qtbase), but in a way that allows a Qt module to override it in its own .cmake.conf file if required (e.g. to address the issues identified by policy warnings at a later time). The policies are modified at the start of the call to qt_build_repo_begin(). For commands defined by the qtbase module, qtbase needs to be in control of the policy settings at the point where those commands are defined. The above mechanism should not affect the policy settings for these commands, so the various *Config.cmake.in files must not specify policy ranges in a way that a Qt module's .cmake.conf file could influence. Starting with CMake 3.12, policies can be specified as a version range with the cmake_minimum_required() and cmake_policy() commands. All policies introduced in CMake versions up to the upper limit of that range will be set to NEW. The actual version of CMake being used only has to be at least the lower limit of the specified version range. This change uses cmake_minimum_required() rather than cmake_policy() due to the latter not halting further processing upon failure. See the following: https://gitlab.kitware.com/cmake/cmake/-/issues/21557 Task-number: QTBUG-88700 Pick-to: 6.0 Change-Id: I0a1f2611dd629f847a18186394f500d7f52753bc Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-30 07:46:49 +00:00
# Returns the oldest CMake version for which NEW policies should be enabled.
# It can be older than the minimum supported or computed CMake version, as it
# is only used for policy settings. The currently running CMake must not be
# older than this version though (doing so will result in an error).
function(qt_internal_get_min_new_policy_cmake_version out_var)
# QT_MIN_NEW_POLICY_CMAKE_VERSION is set either in .cmake.conf or in
# QtBuildInternalsExtras.cmake when building a child repo.
set(lower_version "${QT_MIN_NEW_POLICY_CMAKE_VERSION}")
set(${out_var} "${lower_version}" PARENT_SCOPE)
endfunction()
# Returns the latest CMake version for which NEW policies should be enabled.
# This cannot be less than the minimum CMake policy version or we will end up
# specifying a version range with the max less than the min.
function(qt_internal_get_max_new_policy_cmake_version out_var)
# QT_MAX_NEW_POLICY_CMAKE_VERSION is set either in .cmake.conf or in
# QtBuildInternalsExtras.cmake when building a child repo.
set(upper_version "${QT_MAX_NEW_POLICY_CMAKE_VERSION}")
qt_internal_get_min_new_policy_cmake_version(lower_version)
if(upper_version VERSION_LESS lower_version)
set(upper_version ${lower_version})
endif()
set(${out_var} "${upper_version}" PARENT_SCOPE)
endfunction()
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
function(qt_internal_check_for_suitable_cmake_version)
# Implementation note.
CMake: Enable NEW policies by CMake version with a global default When a CMake release introduces a new policy that affects most Qt modules, it may be appropriate to make each module aware of that newer CMake version and use the NEW policy without raising the minimum CMake version requirement. To reduce the churn associated with making that change across all Qt modules individually, this change allows it to be updated in a central place (qtbase), but in a way that allows a Qt module to override it in its own .cmake.conf file if required (e.g. to address the issues identified by policy warnings at a later time). The policies are modified at the start of the call to qt_build_repo_begin(). For commands defined by the qtbase module, qtbase needs to be in control of the policy settings at the point where those commands are defined. The above mechanism should not affect the policy settings for these commands, so the various *Config.cmake.in files must not specify policy ranges in a way that a Qt module's .cmake.conf file could influence. Starting with CMake 3.12, policies can be specified as a version range with the cmake_minimum_required() and cmake_policy() commands. All policies introduced in CMake versions up to the upper limit of that range will be set to NEW. The actual version of CMake being used only has to be at least the lower limit of the specified version range. This change uses cmake_minimum_required() rather than cmake_policy() due to the latter not halting further processing upon failure. See the following: https://gitlab.kitware.com/cmake/cmake/-/issues/21557 Task-number: QTBUG-88700 Pick-to: 6.0 Change-Id: I0a1f2611dd629f847a18186394f500d7f52753bc Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-30 07:46:49 +00:00
# The very first cmake_minimum_required() call can't be placed in an include()d file.
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
# It causes CMake to fail to configure with 'No cmake_minimum_required command is present.'
CMake: Enable NEW policies by CMake version with a global default When a CMake release introduces a new policy that affects most Qt modules, it may be appropriate to make each module aware of that newer CMake version and use the NEW policy without raising the minimum CMake version requirement. To reduce the churn associated with making that change across all Qt modules individually, this change allows it to be updated in a central place (qtbase), but in a way that allows a Qt module to override it in its own .cmake.conf file if required (e.g. to address the issues identified by policy warnings at a later time). The policies are modified at the start of the call to qt_build_repo_begin(). For commands defined by the qtbase module, qtbase needs to be in control of the policy settings at the point where those commands are defined. The above mechanism should not affect the policy settings for these commands, so the various *Config.cmake.in files must not specify policy ranges in a way that a Qt module's .cmake.conf file could influence. Starting with CMake 3.12, policies can be specified as a version range with the cmake_minimum_required() and cmake_policy() commands. All policies introduced in CMake versions up to the upper limit of that range will be set to NEW. The actual version of CMake being used only has to be at least the lower limit of the specified version range. This change uses cmake_minimum_required() rather than cmake_policy() due to the latter not halting further processing upon failure. See the following: https://gitlab.kitware.com/cmake/cmake/-/issues/21557 Task-number: QTBUG-88700 Pick-to: 6.0 Change-Id: I0a1f2611dd629f847a18186394f500d7f52753bc Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-30 07:46:49 +00:00
# The first cmake_minimum_required() must be called directly in the top-level CMakeLists.txt
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
# file.
# That's why this function only handles output of warnings, and doesn't try to set the required
# version.
qt_internal_check_minimum_cmake_version()
qt_internal_warn_about_unsuitable_cmake_versions()
endfunction()
# Function to be used in child repos like qtsvg to require a minimum CMake version.
#
CMake: Enable NEW policies by CMake version with a global default When a CMake release introduces a new policy that affects most Qt modules, it may be appropriate to make each module aware of that newer CMake version and use the NEW policy without raising the minimum CMake version requirement. To reduce the churn associated with making that change across all Qt modules individually, this change allows it to be updated in a central place (qtbase), but in a way that allows a Qt module to override it in its own .cmake.conf file if required (e.g. to address the issues identified by policy warnings at a later time). The policies are modified at the start of the call to qt_build_repo_begin(). For commands defined by the qtbase module, qtbase needs to be in control of the policy settings at the point where those commands are defined. The above mechanism should not affect the policy settings for these commands, so the various *Config.cmake.in files must not specify policy ranges in a way that a Qt module's .cmake.conf file could influence. Starting with CMake 3.12, policies can be specified as a version range with the cmake_minimum_required() and cmake_policy() commands. All policies introduced in CMake versions up to the upper limit of that range will be set to NEW. The actual version of CMake being used only has to be at least the lower limit of the specified version range. This change uses cmake_minimum_required() rather than cmake_policy() due to the latter not halting further processing upon failure. See the following: https://gitlab.kitware.com/cmake/cmake/-/issues/21557 Task-number: QTBUG-88700 Pick-to: 6.0 Change-Id: I0a1f2611dd629f847a18186394f500d7f52753bc Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-30 07:46:49 +00:00
# Such repos don't have the required version information at cmake_minimum_required() time, that's
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
# why we provide this function to be called at a time when the info is available.
function(qt_internal_require_suitable_cmake_version)
qt_internal_check_for_suitable_cmake_version()
qt_internal_get_computed_minimum_cmake_version(computed_min_version)
if(CMAKE_VERSION VERSION_LESS computed_min_version)
message(FATAL_ERROR "CMake ${computed_min_version} or higher is required. "
"You are running version ${CMAKE_VERSION}")
endif()
endfunction()
function(qt_internal_check_minimum_cmake_version)
qt_internal_get_qt_supported_minimum_cmake_version(min_supported_version)
qt_internal_get_computed_minimum_cmake_version(computed_min_version)
if(NOT min_supported_version STREQUAL computed_min_version
AND computed_min_version VERSION_LESS min_supported_version)
message(WARNING
"The minimum required CMake version to build Qt is '${min_supported_version}'. "
"You have explicitly chosen to require a lower minimum CMake version, namely '${computed_min_version}'. "
"Building Qt with such a CMake version is not officially supported. Use at your own risk.")
endif()
endfunction()
function(qt_internal_warn_about_unsuitable_cmake_versions)
set(unsuitable_versions "")
# Touching a library's source file causes unnecessary rebuilding of unrelated targets.
# https://gitlab.kitware.com/cmake/cmake/-/issues/21020
list(APPEND unsuitable_versions "3.18.0")
# Ninja Multi-Config race condition overrides response files of different configurations
# https://gitlab.kitware.com/cmake/cmake/-/issues/20961
# https://gitlab.kitware.com/cmake/cmake/-/issues/21050 (follow up issue)
list(APPEND unsuitable_versions "3.18.1")
# AUTOMOC dependencies are not properly created when using Ninja Multi-Config.
# https://gitlab.kitware.com/cmake/cmake/-/issues/21118
#
# Also until 3.18.2 inclusive, AUTOMOC dependencies are out-of-date if a previously header
# disappears (for example when upgrading a compiler)
# https://gitlab.kitware.com/cmake/cmake/-/issues/21136
#
# Also multi-arch PCH doesn't work on iOS. Can't quite find the original upstream CMake issue
# but the Qt one was detected at https://codereview.qt-project.org/c/qt/qt5/+/310947
# And a follow up issue regarding PCH and -fembed-bitcode failing.
# https://gitlab.kitware.com/cmake/cmake/-/issues/21163
list(APPEND unsuitable_versions "3.18.2")
Warn if using CMake 3.20.0 due to potential cyclic dependencies CMake 3.20.0 can create autogen-related cyclic dependencies that are only detected at build time by Ninja, which then fails with a build error. Warn and advise to use a different CMake version instead. Pick-to: 6.1 6.0 Change-Id: I9bef973ad2efdb69f28d6a9e0584b543be59f17f Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2021-03-30 00:35:00 +00:00
# Cyclic dependencies are created when mixing AUTOMOC/AUTOUIC with sources
# that have their SKIP_MOC or SKIP_UIC source file properties set to true.
# https://gitlab.kitware.com/cmake/cmake/-/issues/21977
list(APPEND unsuitable_versions "3.20.0")
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
foreach(unsuitable_version ${unsuitable_versions})
if(CMAKE_VERSION VERSION_EQUAL unsuitable_version)
message(WARNING
"The CMake version you are using is known to cause issues when building Qt. "
"Please upgrade to a newer version. "
"CMake version used: '${unsuitable_version}'")
endif()
endforeach()
Lower the CMake minimum required version for single-config builds Ubuntu 20.04 is a supported platform and comes with CMake 3.16. The current state of the Qt build works fine with this CMake version, mainly because the default build on Linux is single-config. For multi-config builds we have higher version requirements as documented in cmake/README.md. This lowers the barrier for users using single-config builds who don't want or cannot upgrade to CMake >= 3.18. For Ninja Multi-Config builds, which were introduced by CMake 3.17, we yield a warning that 3.18.3 is the lowest supported version. Pick-to: 6.0 Change-Id: Ia918b9f2b494508e86301ffc0e138d3ad4dbaf86 Reviewed-by: Craig Scott <craig.scott@qt.io> Reviewed-by: Lars Knoll <lars.knoll@qt.io>
2021-01-08 13:31:26 +00:00
# Ninja Multi-Config was introduced in 3.17, but we recommend 3.18.
set(min_nmc_cmake_version "3.18.3")
if(CMAKE_GENERATOR STREQUAL "Ninja Multi-Config"
AND CMAKE_VERSION VERSION_LESS ${min_nmc_cmake_version})
message(WARNING
"You are using CMake ${CMAKE_VERSION} with the Ninja Multi-Config generator. "
"This combination is unsupported. "
"Please upgrade to at least CMake ${min_nmc_cmake_version}. ")
endif()
CMake: Bump the minimum required CMake version to build Qt to 3.18 Add a new function that returns the minimum CMake version required to build Qt. Pass that value to cmake_minimum_required() when building qtbase and its standalone tests. The minimum supported CMake version is read from qtbase/.cmake.conf and its value should be updated when the need arises. It's the main source of truth for all repos. Provide a way to lower the minimum CMake version at configure time by passing a value via QT_FORCE_MIN_CMAKE_VERSION. This is not an officially supported way of building Qt. If the specified version is lower than Qt's supported minimum, show a warning. Nevertheless the option is useful for testing how Qt builds with a different minimum CMake version due to different policies being enabled by default. Issue warnings for CMake versions that are higher than the minimum version but are known to cause issues when building Qt. A counterpart change is needed in qt5 to ensure the minimum CMake version is set at the proper time for top-level builds. Ideally we would use the same 'check the CMake minimum version` code in all our repositories, but that will cause lots of duplication because we can't really find_package() the code and doing something like include(../qtbase/foo.cmake) hardcodes assumptions about repo locations. So for now we don't bump the minimum version in child repo cmake_minimum_required calls (qtsvg, qtdeclarative, etc). Instead we record both the minimum supported version and the computed minimum version (in case a different version was forced) in QtBuildInternalsExtra.cmake. Then we require qtbase's computed min version in qt_build_repo_begin(). This won't set policies as cmake_minimum_required would, but at least it propagates what minimum CMake version should be used for child repos. We might still have to bump the versions in child repos at some point. Task-number: QTBUG-88086 Change-Id: Ida1c0d5d3e0fbb15d2aee9b68abab7a1648774b9 Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org> Reviewed-by: Cristian Adam <cristian.adam@qt.io>
2020-10-30 16:42:34 +00:00
endfunction()
CMake: Enable NEW policies by CMake version with a global default When a CMake release introduces a new policy that affects most Qt modules, it may be appropriate to make each module aware of that newer CMake version and use the NEW policy without raising the minimum CMake version requirement. To reduce the churn associated with making that change across all Qt modules individually, this change allows it to be updated in a central place (qtbase), but in a way that allows a Qt module to override it in its own .cmake.conf file if required (e.g. to address the issues identified by policy warnings at a later time). The policies are modified at the start of the call to qt_build_repo_begin(). For commands defined by the qtbase module, qtbase needs to be in control of the policy settings at the point where those commands are defined. The above mechanism should not affect the policy settings for these commands, so the various *Config.cmake.in files must not specify policy ranges in a way that a Qt module's .cmake.conf file could influence. Starting with CMake 3.12, policies can be specified as a version range with the cmake_minimum_required() and cmake_policy() commands. All policies introduced in CMake versions up to the upper limit of that range will be set to NEW. The actual version of CMake being used only has to be at least the lower limit of the specified version range. This change uses cmake_minimum_required() rather than cmake_policy() due to the latter not halting further processing upon failure. See the following: https://gitlab.kitware.com/cmake/cmake/-/issues/21557 Task-number: QTBUG-88700 Pick-to: 6.0 Change-Id: I0a1f2611dd629f847a18186394f500d7f52753bc Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
2020-11-30 07:46:49 +00:00
# Functions don't have their own policy scope, so the policy settings modified
# here will be those of the caller's policy scope. Note that these settings
# will only apply to functions and macros defined after this function is called,
# but not to any that are already defined. Ordinary CMake code not inside a
# function or macro will be affected by these policy settings too.
function(qt_internal_upgrade_cmake_policies)
qt_internal_get_computed_minimum_cmake_version(lower_version)
qt_internal_get_max_new_policy_cmake_version(upper_version)
cmake_minimum_required(VERSION ${lower_version}...${upper_version})
endfunction()
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