Move the linking logic of the object libraries to a common function

The linking logic of object libraries should be reusable outside of the
resource context. This introduces a
__qt_internal_propagate_object_library function that prepares all the
necessary genexes to link and propagate the object library to the
end-point executable.

Rename resource object finalizer API to make the naming more generic
to object libraries of any kind.

Amends 5fb99e3860eb43f4bacacec7f4a4626cb0159b14

Pick-to: 6.2
Task-number: QTBUG-93002
Task-number: QTBUG-94528
Change-Id: I69d0f34c0dadbd67232de91035aaa53af93d1fa1
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

cmake/QtPublicTargetHelpers.cmake

@@ -87,8 +87,8 @@ function(__qt_internal_check_link_order_matters)
     endif()
 endfunction()
 
-function(__qt_internal_process_dependency_resource_objects target)
+function(__qt_internal_process_dependency_object_libraries target)
-    # The CMake versions greater than 3.21 take care about the resource object files order in a
+    # The CMake versions greater than 3.21 take care about the order of object files in a
     # linker line, it's expected that all object files are located at the beginning of the linker
     # line.
     # So circular dependencies between static libraries and object files are resolved and no need
@@ -98,68 +98,68 @@ function(__qt_internal_process_dependency_resource_objects target)
     if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.21)
         return()
     endif()
-    get_target_property(processed ${target} _qt_resource_object_finalizers_processed)
+    get_target_property(processed ${target} _qt_object_libraries_finalizer_processed)
     if(processed)
         return()
     endif()
-    set_target_properties(${target} PROPERTIES _qt_resource_object_finalizers_processed TRUE)
+    set_target_properties(${target} PROPERTIES _qt_object_libraries_finalizer_processed TRUE)
 
     __qt_internal_check_finalizer_mode(${target}
         use_finalizer_mode
-        resource_objects
+        object_libraries
     )
 
     if(NOT use_finalizer_mode)
         return()
     endif()
 
-    __qt_internal_collect_dependency_resource_objects(${target} resource_objects)
+    __qt_internal_collect_dependency_object_libraries(${target} objects)
-    target_sources(${target} PRIVATE "${resource_objects}")
+    target_sources(${target} PRIVATE "${objects}")
 endfunction()
 
-function(__qt_internal_collect_dependency_resource_objects target out_var)
+function(__qt_internal_collect_dependency_object_libraries target out_var)
-    set_property(GLOBAL PROPERTY _qt_resource_processed_targets "")
+    set_property(GLOBAL PROPERTY _qt_processed_object_libraries "")
 
-    __qt_internal_collect_resource_objects_recursively(resource_targets ${target} ${target})
+    __qt_internal_collect_object_libraries_recursively(object_libraries ${target} ${target})
 
-    # Collect resource objects of plugins and plugin dependencies.
+    # Collect object libraries of plugins and plugin dependencies.
     __qt_internal_collect_plugin_targets_from_dependencies(${target} plugin_targets)
-    __qt_internal_collect_dependency_plugin_resource_objects(${target}
+    __qt_internal_collect_dependency_plugin_object_libraries(${target}
         "${plugin_targets}"
-        plugin_resource_objects
+        plugin_objects
     )
 
-    set_property(GLOBAL PROPERTY _qt_resource_processed_targets "")
+    set_property(GLOBAL PROPERTY _qt_processed_object_libraries "")
 
-    list(REMOVE_DUPLICATES resource_targets)
+    list(REMOVE_DUPLICATES object_libraries)
-    set(resource_objects "")
+    set(objects "")
-    foreach(dep IN LISTS resource_targets)
+    foreach(dep IN LISTS object_libraries)
-        list(PREPEND resource_objects "$<TARGET_OBJECTS:${dep}>")
+        list(PREPEND objects "$<TARGET_OBJECTS:${dep}>")
     endforeach()
 
-    set(${out_var} "${plugin_resource_objects};${resource_objects}" PARENT_SCOPE)
+    set(${out_var} "${plugin_objects};${objects}" PARENT_SCOPE)
 endfunction()
 
-function(__qt_internal_collect_dependency_plugin_resource_objects target plugin_targets out_var)
+function(__qt_internal_collect_dependency_plugin_object_libraries target plugin_targets out_var)
-    set(plugin_resource_objects "")
+    set(plugin_objects "")
     foreach(plugin_target IN LISTS plugin_targets)
-        __qt_internal_collect_resource_objects_recursively(plugin_resource_targets
+        __qt_internal_collect_object_libraries_recursively(plugin_object_libraries
             "${QT_CMAKE_EXPORT_NAMESPACE}::${plugin_target}"
             ${target}
         )
         __qt_internal_get_static_plugin_condition_genex("${plugin_target}" plugin_condition)
 
-        foreach(plugin_resource_target IN LISTS plugin_resource_targets)
+        foreach(plugin_object_library IN LISTS plugin_object_libraries)
-            list(APPEND plugin_resource_objects
+            list(APPEND plugin_objects
-                "$<${plugin_condition}:$<TARGET_OBJECTS:${plugin_resource_target}>>"
+                "$<${plugin_condition}:$<TARGET_OBJECTS:${plugin_object_library}>>"
             )
         endforeach()
     endforeach()
-    set(${out_var} "${plugin_resource_objects}" PARENT_SCOPE)
+    set(${out_var} "${plugin_objects}" PARENT_SCOPE)
 endfunction()
 
-function(__qt_internal_collect_resource_objects_recursively out_var target initial_target)
+function(__qt_internal_collect_object_libraries_recursively out_var target initial_target)
-    get_property(resource_processed_targets GLOBAL PROPERTY _qt_resource_processed_targets)
+    get_property(processed_object_libraries GLOBAL PROPERTY _qt_processed_object_libraries)
 
     set(interface_libs "")
     set(libs "")
@@ -171,7 +171,7 @@ function(__qt_internal_collect_resource_objects_recursively out_var target initi
         get_target_property(libs ${target} LINK_LIBRARIES)
     endif()
 
-    set(resource_targets "")
+    set(object_libraries "")
     foreach(lib IN LISTS libs interface_libs)
         if(TARGET ${lib})
             get_target_property(aliased_target ${lib} ALIASED_TARGET)
@@ -179,26 +179,28 @@ function(__qt_internal_collect_resource_objects_recursively out_var target initi
                 set(lib ${aliased_target})
             endif()
 
-            if(${lib} IN_LIST resource_processed_targets)
+            if(${lib} IN_LIST processed_object_libraries)
                 continue()
             else()
-                list(APPEND resource_processed_targets ${lib})
+                list(APPEND processed_object_libraries ${lib})
-                set_property(GLOBAL APPEND PROPERTY _qt_resource_processed_targets ${lib})
+                set_property(GLOBAL APPEND PROPERTY _qt_processed_object_libraries ${lib})
             endif()
 
-            get_target_property(is_qt_resource ${lib} _is_qt_resource_target)
+            get_target_property(is_qt_propagated_object_library ${lib}
-            if(is_qt_resource)
+                _is_qt_propagated_object_library
-                list(APPEND resource_targets ${lib})
+            )
+            if(is_qt_propagated_object_library)
+                list(APPEND object_libraries ${lib})
             else()
-                __qt_internal_collect_resource_objects_recursively(next_level_resources
+                __qt_internal_collect_object_libraries_recursively(next_level_object_libraries
                     ${lib}
                     ${initial_target}
                 )
-                list(APPEND resource_targets ${next_level_resources})
+                list(APPEND object_libraries ${next_level_object_libraries})
             endif()
         endif()
     endforeach()
-    set(${out_var} "${resource_targets}" PARENT_SCOPE)
+    set(${out_var} "${object_libraries}" PARENT_SCOPE)
 endfunction()
 
 function(__qt_internal_promote_target_to_global target)

src/corelib/Qt6CoreMacros.cmake

@@ -596,7 +596,7 @@ function(_qt_internal_finalize_executable target)
     get_target_property(is_immediately_finalized "${target}" _qt_is_immediately_finalized)
     if(NOT is_immediately_finalized)
         __qt_internal_apply_plugin_imports_finalizer_mode("${target}")
-        __qt_internal_process_dependency_resource_objects("${target}")
+        __qt_internal_process_dependency_object_libraries("${target}")
     endif()
 
     set_target_properties(${target} PROPERTIES _qt_executable_is_finalized TRUE)
@@ -914,13 +914,13 @@ endif()
 # It makes sense to manually disable the finalizer of the resource object if you are using
 # linkers other than ld, since the dependencies between resource objects and static libraries
 # are resolved correctly by them.
-function(qt6_enable_resource_objects_finalizer_mode target enabled)
+function(qt6_enable_object_libraries_finalizer_mode target enabled)
-    __qt_internal_enable_finalizer_mode(${target} resource_objects ${enabled})
+    __qt_internal_enable_finalizer_mode(${target} object_libraries ${enabled})
 endfunction()
 
 if(NOT QT_NO_CREATE_VERSIONLESS_FUNCTIONS)
-    function(qt_enable_resource_objects_finalizer_mode)
+    function(qt_enable_object_libraries_finalizer_mode)
-        qt6_enable_resource_objects_finalizer_mode(${ARGV})
+        qt6_enable_object_libraries_finalizer_mode(${ARGV})
     endfunction()
 endif()
 
@@ -1408,6 +1408,107 @@ function(__qt_get_relative_resource_path_for_file output_alias file)
     set(${output_alias} ${alias} PARENT_SCOPE)
 endfunction()
 
+# Performs linking and propagation of the object library via the target's usage requirements.
+# Arguments:
+# NO_LINK_OBJECT_LIBRARY_REQUIREMENTS_TO_TARGET skip linking of ${object_library} to ${target}, only
+#   propagate $<TARGET_OBJECTS:${object_library}> by linking it to ${target}. It's useful in case
+#   if ${object_library} depends on the ${target}. E.g. resource libraries depend on the Core
+#   library so linking them back to Core will cause a CMake error.
+#
+# EXTRA_CONDITIONS object library specific conditions to be checked before link the object library
+#   to the end-point executable.
+function(__qt_internal_propagate_object_library target object_library)
+    set(options NO_LINK_OBJECT_LIBRARY_REQUIREMENTS_TO_TARGET)
+    set(single_args "")
+    set(multi_args EXTRA_CONDITIONS)
+    cmake_parse_arguments(arg "${options}" "${single_args}" "${multi_args}" ${ARGN})
+
+    target_link_libraries(${object_library} PRIVATE ${QT_CMAKE_EXPORT_NAMESPACE}::Platform)
+    _qt_internal_copy_dependency_properties(${object_library} ${target} PRIVATE_ONLY)
+
+    # After internal discussion we decided to not rely on the linker order that CMake
+    # offers, until CMake provides the guaranteed linking order that suites our needs in a
+    # future CMake version.
+    # All object libraries mark themselves with the _is_qt_propagated_object_library property.
+    # Using a finalizer approach we walk through the target dependencies and look for libraries
+    # using the _is_qt_propagated_object_library property. Then, objects of the collected libraries
+    # are moved to the beginnig of the linker line using target_sources.
+    #
+    # Note: target_link_libraries works well with linkers other than ld. If user didn't enforce
+    # a finalizer we rely on linker to resolve circular dependencies between objects and static
+    # libraries.
+    set_property(TARGET ${object_library} PROPERTY _is_qt_propagated_object_library TRUE)
+    set_property(TARGET ${object_library} APPEND PROPERTY
+        EXPORT_PROPERTIES _is_qt_propagated_object_library
+    )
+
+    # Keep the implicit linking if finalizers are not used.
+    set(not_finalizer_mode_condition
+        "$<NOT:$<BOOL:$<TARGET_PROPERTY:_qt_object_libraries_finalizer_mode>>>"
+    )
+
+    # Collect object library specific conditions.
+    if(arg_EXTRA_CONDITIONS)
+        list(JOIN arg_EXTRA_CONDITIONS "," extra_conditions)
+    else()
+        set(extra_conditions "$<BOOL:TRUE>")
+    endif()
+
+    # Do not litter the static libraries
+    set(not_static_condition
+        "$<NOT:$<STREQUAL:$<TARGET_PROPERTY:TYPE>,STATIC_LIBRARY>>"
+    )
+
+    # Check if link order matters for the Platform.
+    set(platform_link_order_property
+        "$<TARGET_PROPERTY:${QT_CMAKE_EXPORT_NAMESPACE}::Platform,_qt_link_order_matters>"
+    )
+    set(platform_link_order_condition
+        "$<BOOL:${platform_link_order_property}>"
+    )
+
+    # Use TARGET_NAME to have the correct namespaced name in the exports.
+    set(objects "$<TARGET_OBJECTS:$<TARGET_NAME:${object_library}>>")
+
+    # Collect link conditions for the target_sources call.
+    string(JOIN "" target_sources_genex
+        "$<"
+            "$<AND:"
+                "${not_finalizer_mode_condition},"
+                "${not_static_condition},"
+                "${platform_link_order_condition},"
+                "${extra_conditions}"
+            ">"
+        ":${objects}>"
+    )
+    target_sources(${target} INTERFACE
+        "${target_sources_genex}"
+    )
+
+    # Collect link conditions for the target_link_libraries call.
+    string(JOIN "" target_link_libraries_genex
+        "$<"
+            "$<AND:"
+                "${not_finalizer_mode_condition},"
+                "${not_static_condition},"
+                "$<NOT:${platform_link_order_condition}>,"
+                "${extra_conditions}"
+            ">"
+        ":${objects}>"
+    )
+    target_link_libraries(${target} INTERFACE
+        "${target_link_libraries_genex}"
+    )
+
+    if(NOT arg_NO_LINK_OBJECT_LIBRARY_REQUIREMENTS_TO_TARGET)
+        # It's necessary to link the object library target, since we want to pass the object library
+        # dependencies to the 'target'. Interface linking doesn't add the objects of the library to
+        # the end-point linker line but propagates all the dependencies of the object_library added
+        # before or AFTER the line below.
+        target_link_libraries(${target} INTERFACE ${object_library})
+    endif()
+endfunction()
+
 function(__qt_propagate_generated_resource target resource_name generated_source_code output_generated_target)
     get_target_property(type ${target} TYPE)
     if(type STREQUAL STATIC_LIBRARY)
@@ -1424,13 +1525,10 @@ function(__qt_propagate_generated_resource target resource_name generated_source
             "$<TARGET_PROPERTY:${QT_CMAKE_EXPORT_NAMESPACE}::Core,INTERFACE_COMPILE_DEFINITIONS>"
         )
 
-        target_link_libraries(${resource_target} PRIVATE ${QT_CMAKE_EXPORT_NAMESPACE}::Platform)
-        _qt_internal_copy_dependency_properties(${resource_target} ${target} PRIVATE_ONLY)
-
         # Special handling is required for the Core library resources. The linking of the Core
         # library to the resources adds a circular dependency. This leads to the wrong
-        # objects/library order in the linker command line, since the Core library target is resolved
+        # objects/library order in the linker command line, since the Core library target is
-        # first.
+        # resolved first.
         if(NOT target STREQUAL "Core")
             target_link_libraries(${resource_target} INTERFACE ${QT_CMAKE_EXPORT_NAMESPACE}::Core)
         endif()
@@ -1447,73 +1545,13 @@ function(__qt_propagate_generated_resource target resource_name generated_source
         set_property(TARGET ${resource_target} APPEND PROPERTY
             _qt_resource_generated_cpp_relative_path "${generated_cpp_file_relative_path}")
 
-        # After internal discussion we decided to not rely on the linker order that CMake
+        if(target STREQUAL "Core")
-        # offers, until CMake provides the guaranteed linking order that suites our needs in a
+            set(skip_direct_linking NO_LINK_OBJECT_LIBRARY_REQUIREMENTS_TO_TARGET)
-        # future CMake version.
-        # All resource object libraries mark themselves with the _is_qt_resource_target property.
-        # Using a finalizer approach we walk through the target dependencies and look for
-        # resource libraries using the _is_qt_resource_target property. Then, resource objects of
-        # the collected libraries are moved to the beginnig of the linker line using target_sources.
-        #
-        # target_link_libraries works well with linkers other than ld. If user didn't enforce
-        # a finalizer we rely on linker to resolve circular dependencies between resource
-        # objects and static libraries.
-        set_property(TARGET ${resource_target} PROPERTY _is_qt_resource_target TRUE)
-        set_property(TARGET ${resource_target} APPEND PROPERTY
-            EXPORT_PROPERTIES _is_qt_resource_target
-        )
-
-        # Keep the implicit linking if finalizers are not used.
-        set(not_finalizer_mode_condition
-            "$<NOT:$<BOOL:$<TARGET_PROPERTY:_qt_resource_objects_finalizer_mode>>>"
-        )
-        # Do not litter the static libraries
-        set(not_static_condition
-            "$<NOT:$<STREQUAL:$<TARGET_PROPERTY:TYPE>,STATIC_LIBRARY>>"
-        )
-        set(resource_objects "$<TARGET_OBJECTS:$<TARGET_NAME:${resource_target}>>")
-
-        set(platform_link_order_property
-            "$<TARGET_PROPERTY:${QT_CMAKE_EXPORT_NAMESPACE}::Platform,_qt_link_order_matters>"
-        )
-        set(platform_link_order_condition
-            "$<BOOL:${platform_link_order_property}>"
-        )
-
-        string(JOIN "" target_sources_genex
-            "$<"
-                "$<AND:"
-                    "${not_finalizer_mode_condition},"
-                    "${not_static_condition},"
-                    "${platform_link_order_condition}"
-                ">"
-            ":${resource_objects}>"
-        )
-        target_sources(${target} INTERFACE
-            "${target_sources_genex}"
-        )
-
-        string(JOIN "" target_link_libraries_genex
-            "$<"
-                "$<AND:"
-                    "${not_finalizer_mode_condition},"
-                    "${not_static_condition},"
-                    "$<NOT:${platform_link_order_condition}>"
-                ">"
-            ":${resource_objects}>"
-        )
-        target_link_libraries(${target} INTERFACE
-            "${target_link_libraries_genex}"
-        )
-
-        if(NOT target STREQUAL "Core")
-            # It's necessary to link the object library target, since we want to pass
-            # the object library dependencies to the 'target'. Interface linking doesn't
-            # add the objects of the resource library to the end-point linker line
-            # but propagates all the dependencies of the resource_target added before
-            # or AFTER the line below.
-            target_link_libraries(${target} INTERFACE ${resource_target})
         endif()
+        __qt_internal_propagate_object_library(${target} ${resource_target}
+            ${skip_direct_linking}
+        )
+
         set(${output_generated_target} "${resource_target}" PARENT_SCOPE)
     else()
         set(${output_generated_target} "" PARENT_SCOPE)

tests/auto/cmake/test_static_resources/test_static_resources_propagation/CMakeLists.txt

@@ -81,7 +81,7 @@ if(NOT link_order_matters)
 
     if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.19)
         qt_add_executable(test_static_resources_propagation_not_finalize main.cpp)
-        qt6_enable_resource_objects_finalizer_mode(
+        qt6_enable_object_libraries_finalizer_mode(
             test_static_resources_propagation_not_finalize FALSE
         )
         set_target_properties(test_static_resources_propagation_not_finalize PROPERTIES