qt5base-lts/cmake/QtCMakeVersionHelpers.cmake
Craig Scott 6442116078 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>
2021-04-12 12:24:56 +11:00

154 lines
7.6 KiB
CMake

# 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()
# 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()
function(qt_internal_check_for_suitable_cmake_version)
# Implementation note.
# The very first cmake_minimum_required() call can't be placed in an include()d file.
# It causes CMake to fail to configure with 'No cmake_minimum_required command is present.'
# The first cmake_minimum_required() must be called directly in the top-level CMakeLists.txt
# 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.
#
# Such repos don't have the required version information at cmake_minimum_required() time, that's
# 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")
# 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")
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()
# 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()
endfunction()
# 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()