qt5base-lts/cmake/QtPlatformTargetHelpers.cmake

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# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: BSD-3-Clause
# Defines the public Qt::Platform target, which serves as a dependency for all internal Qt target
# as well as user projects consuming Qt.
function(qt_internal_setup_public_platform_target)
qt_internal_get_platform_definition_include_dir(
install_interface_definition_dir
build_interface_definition_dir
)
## QtPlatform Target:
add_library(Platform INTERFACE)
add_library(Qt::Platform ALIAS Platform)
add_library(${INSTALL_CMAKE_NAMESPACE}::Platform ALIAS Platform)
target_include_directories(Platform
INTERFACE
$<BUILD_INTERFACE:${build_interface_definition_dir}>
$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
$<INSTALL_INTERFACE:${install_interface_definition_dir}>
$<INSTALL_INTERFACE:${INSTALL_INCLUDEDIR}>
)
target_compile_definitions(Platform INTERFACE ${QT_PLATFORM_DEFINITIONS})
CMake: Record used package version for each target dependency When recording which package version to look for in QtFooModuleDependencies.cmake and other files like it, instead of using PROJECT_VERSION, use the version of the package that contains the dependency. For example if we're hypothetically building the qtdeclarative repo from the 6.4 branch, against an installed 6.2 qtbase, then the Qt6QmlModuleDependencies.cmake file will have a find_package(Qt6Core 6.2) call because qtdeclarative's find_package(Qt6Core) call found a 6.2 Core when it was configured. This allows switching the versioning scheme of specific Qt modules that might not want to follow the general Qt versioning scheme. The first candidate would be QtWebEngine which might want to follow the Chromium versioning scheme, something like Qt 6.94.0 where 94 is the Chromium major version. Implementation notes. We now record the package version of a target in a property called _qt_package_version. We do it for qt modules, plugins, 3rd party libraries, tools and the Platform target. When we try to look up which version to write into the QtFooModuleDependencies.cmake file (or the equivalent Plugins and Tools file), we try to find the version from a few sources: the property mentioned above, then the Qt6{target}_VERSION variable, and finally PROJECT_VERSION. In the latter case, we issue a warning because technically that should never have to happen, and it's a bug or an unforeseen case if it does. A few more places also need adjustments: - package versions to look for when configuring standalone tests and generating standalone tests Config files - handling of tools packages - The main Qt6 package lookup in each Dependencies.cmake files Note that there are some requirements and consequences in case a module wants to use a different versioning scheme like 6.94.0. Requirements. - The root CMakeLists.txt file needs to call find_package with a version different from the usual PROJECT_VERSION. Ideally it should look for a few different Qt versions which are known to be compatible, for example the last stable and LTS versions, or just the lowest supported Qt version, e.g. 6.2.6 or whenever this change would land in the 6.2 branch. - If the repository has multiple modules, some of which need to follow the Qt versioning scheme and some not, project(VERSION x.y.z) calls need to be carefully placed in subdirectory scopes with appropriate version numbers, so that qt_internal_add_module / _tool / _plugin pick up the correct version. Consequences. - The .so / .dylib names will contain the new version, e.g. .so.6.94 - Linux ELF symbols will contain the new versions - syncqt private headers will now exist under a include/QtFoo/6.94.0/QtFoo/private folder - pri and prl files will also contain the new version numbers - pkg-config .pc files contain the new version numbers - It won't be possible to write find_package(Qt6 6.94 COMPONENTS WebEngineWidgets) in user code. One would have to write find_package(Qt6WebEngineWidgets 6.94) otherwise CMake will try to look for Qt6Config 6.94 which won't exist. - Similarly, a find_package(Qt6 6.4 COMPONENTS Widgets WebEngineWidgets) call would always find any kind of WebEngine package that is higher than 6.4, which might be 6.94, 6.95, etc. - In the future, if we fix Qt6Config to pass EXACT to its subcomponent find_package calls, a find_package(Qt6 6.5.0 EXACT COMPONENTS Widgets WebEngineWidgets) would fail to find WebEngineWidgets, because its 6.94.0 version will not be equal to 6.5.0. Currently we don't pass through EXACT, so it's not an issue. Augments 5ffc744b791a114a3180a425dd26e298f7399955 Task-number: QTBUG-103500 Change-Id: I8bdb56bfcbc7f7f6484d1e56651ffc993fd30bab Reviewed-by: Michal Klocek <michal.klocek@qt.io> Reviewed-by: Alexey Edelev <alexey.edelev@qt.io> Reviewed-by: Jörg Bornemann <joerg.bornemann@qt.io>
2022-05-17 06:44:43 +00:00
set_target_properties(Platform PROPERTIES
_qt_package_version "${PROJECT_VERSION}"
)
set_property(TARGET Platform
APPEND PROPERTY
EXPORT_PROPERTIES "_qt_package_version")
# When building on android we need to link against the logging library
# in order to satisfy linker dependencies. Both of these libraries are part of
# the NDK.
if (ANDROID)
target_link_libraries(Platform INTERFACE log)
endif()
if (QT_FEATURE_stdlib_libcpp)
target_compile_options(Platform INTERFACE "$<$<COMPILE_LANGUAGE:CXX>:-stdlib=libc++>")
set(libc_link_option "-stdlib=libc++")
if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.18")
set(libc_link_option "$<$<LINK_LANGUAGE:CXX>:-stdlib=libc++>")
endif()
target_link_options(Platform INTERFACE "${libc_link_option}")
endif()
if (QT_FEATURE_no_direct_extern_access)
target_compile_options(Platform INTERFACE "$<$<CXX_COMPILER_ID:GNU>:-mno-direct-extern-access>")
target_compile_options(Platform INTERFACE "$<$<CXX_COMPILER_ID:Clang>:-fno-direct-access-external-data>")
Enable -mno-direct-extern-access and ELF protected visibility The -mno-direct-extern-access tells the compiler and linker that references to symbols outside this ELF module mustn't be direct and must instead always go through the GOT or PLT (the PLT can additionally be disabled with -fno-plt). The ELF protected visibility tells the compiler and linker that this symbol is present in the dynamic symbol table as an export, but it cannot be interposed by another ELF module. This option is required for user code to link properly to Qt, otherwise they will get linker errors (assuming GNU binutils >= 2.39) or runtime failures (glibc >= 2.35). Both versions of glibc and binutils are older than GCC 12, so it's a safe assumption they are in use and downgrading the toolchain or libc is not supported. Adding this option to the compilation is assured for CMake and qmake-based projects. For example, all accessess to QCoreApplication::self in QtCore, after this change and with GCC 12 are relocation-free and direct: 000000000013ebf0 <QCoreApplicationPrivate::checkInstance(char const*)>: 13ebf0: cmpq $0x0,0x4f73d0(%rip) # 635fc8 <QCoreApplication::self> 13ebf8: setne %al 13ebfb: je a90fe <QCoreApplicationPrivate::checkInstance(char const*) [clone .cold]> 13ec01: ret Meanwhile, accesses to the same variable in other modules are indirect via the GOT: 66650: mov 0x876e1(%rip),%rax # edd38 <QCoreApplication::self@Qt_6> 66657: cmpq $0x0,(%rax) This replaces the -Bsymbolic and -Bsymbolic-functions (broken) functionality that Qt has been using or attempting to use since ~2006. See https://gitlab.com/x86-psABIs/x86-64-ABI/-/issues/8#note_606975128 Change-Id: Iad4b0a3e5c06570b9f5f571b26ed564aa0811e47 Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io> Reviewed-by: Lars Knoll <lars.knoll@qt.io>
2012-01-23 13:46:58 +00:00
endif()
qt_set_msvc_cplusplus_options(Platform INTERFACE)
# Propagate minimum C++ 17 via Platform to Qt consumers (apps), after the global features
# are computed.
qt_set_language_standards_interface_compile_features(Platform)
# By default enable utf8 sources for both Qt and Qt consumers. Can be opted out.
qt_enable_utf8_sources(Platform)
# By default enable unicode on WIN32 platforms for both Qt and Qt consumers. Can be opted out.
qt_internal_enable_unicode_defines(Platform)
# Generate a pkgconfig for Qt::Platform.
qt_internal_generate_pkg_config_file(Platform)
endfunction()
function(qt_internal_get_platform_definition_include_dir install_interface build_interface)
# Used by consumers of prefix builds via INSTALL_INTERFACE (relative path).
set(${install_interface} "${INSTALL_MKSPECSDIR}/${QT_QMAKE_TARGET_MKSPEC}" PARENT_SCOPE)
# Used by qtbase in prefix builds via BUILD_INTERFACE
set(build_interface_base_dir
"${CMAKE_CURRENT_LIST_DIR}/../mkspecs"
)
# Used by qtbase and consumers in non-prefix builds via BUILD_INTERFACE
if(NOT QT_WILL_INSTALL)
set(build_interface_base_dir
"${QT_BUILD_DIR}/${INSTALL_MKSPECSDIR}"
)
endif()
get_filename_component(build_interface_dir
"${build_interface_base_dir}/${QT_QMAKE_TARGET_MKSPEC}"
ABSOLUTE
)
set(${build_interface} "${build_interface_dir}" PARENT_SCOPE)
endfunction()