qt5base-lts/cmake/QtModuleDependencies.cmake.in

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Write find_dependency() calls in Qt Module config files This change introduces a new function called qt_find_package() which can take an extra option called PROVIDED_TARGETS, which associates targets with the package that defines those targets. This is done by setting the INTERFACE_QT_PACKAGE_NAME and INTERFACE_QT_PACKAGE_VERSION properties on the imported targets. This information allows us to generate appropriate find_dependency() calls in a module's Config file for third party libraries. For example when an application links against QtCore, it should also link against zlib and atomic libraries. In order to do that, the library locations first have to be found by CMake. This is achieved by embedding find_dependency(ZLIB) and find_dependency(Atomic) in Qt5CoreDependencies.cmake which is included by Qt5CoreConfig.cmake. The latter is picked up when an application project contains find_package(Qt5Core), and thus all linking dependencies are resolved. The information 'which package provides which targets' is contained in the python json2cmake conversion script. The generated output of the script contains qt_find_package() calls that represent that information. The Qt5CoreDependencies.cmake file and which which dependencies it contains is generated at the QtPostProcess stop. Note that for non-static Qt builds, we only need to propagate public 3rd party libraries. For static builds, we need all third party libraries. In order for the INTERFACE_QT_PACKAGE_NAME property to be read in any scope, the targets on which the property is set, have to be GLOBAL. Also for applications and other modules to find all required third party libraries, we have to install all our custom Find modules, and make sure they define INTERFACE IMPORTED libraries, and not just IMPORTED libraries. Change-Id: I694d6e32d05b96d5e241df0156fc79d0029426aa Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>
2019-04-24 15:14:25 +00:00
# Save old module path, and append a new path that points to the copied over Find modules
# so that find_dependency() can find the third party packages.
set(old_CMAKE_MODULE_PATH "${CMAKE_MODULE_PATH}")
list(APPEND CMAKE_MODULE_PATH "${_import_prefix}/../@INSTALL_CMAKE_NAMESPACE@")
list(APPEND CMAKE_MODULE_PATH "${_import_prefix}/../@INSTALL_CMAKE_NAMESPACE@/3rdparty/extra-cmake-modules/find-modules")
# note: _third_party_deps example: "ICU\\;1.0\\;i18n uc data;ZLIB\\;\\;"
set(_third_party_deps "@third_party_deps@")
foreach(_target_dep ${_third_party_deps})
list(GET _target_dep 0 pkg)
list(GET _target_dep 1 version)
list(GET _target_dep 2 components)
set(find_package_args "${pkg}")
if(version)
list(APPEND find_package_args "${version}")
endif()
if(components)
list(APPEND find_package_args "COMPONENTS" ${components})
endif()
if (NOT ${pkg}_FOUND)
find_dependency(${find_package_args})
endif()
if (NOT ${pkg}_FOUND)
set(@INSTALL_CMAKE_NAMESPACE@@target@_FOUND FALSE)
return()
endif()
endforeach()
# Restore old module path.
set(CMAKE_MODULE_PATH "${old_CMAKE_MODULE_PATH}")
# Find Qt tool package.
set(_tool_deps "@main_module_tool_deps@")
foreach(_target_dep ${_tool_deps})
list(GET _target_dep 0 pkg)
list(GET _target_dep 1 version)
if (NOT ${pkg}_FOUND)
find_dependency(${pkg} ${version})
endif()
if (NOT ${pkg}_FOUND)
set(@INSTALL_CMAKE_NAMESPACE@@target@_FOUND FALSE)
return()
endif()
endforeach()
# note: target_deps example: "Qt5Core\;5.12.0;Qt5Gui\;5.12.0"
set(_target_deps "@target_deps@")
foreach(_target_dep ${_target_deps})
list(GET _target_dep 0 pkg)
list(GET _target_dep 1 version)
if (NOT ${pkg}_FOUND)
find_dependency(${pkg} ${version}
PATHS "${CMAKE_CURRENT_LIST_DIR}/.." NO_DEFAULT_PATH
)
endif()
if (NOT ${pkg}_FOUND)
set(@INSTALL_CMAKE_NAMESPACE@@target@_FOUND FALSE)
return()
endif()
endforeach()