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qt5base-lts/cmake/QtPublicWalkLibsHelpers.cmake
Alexandru Croitor 561fc8107f CMake: Allow promoting the Qt libraries to be global targets 
User projects can set the QT_PROMOTE_TO_GLOBAL_TARGETS variable to
true so that the various imported targets created by find_package(Qt6)
are promoted to global targets.

This would allow a project to find Qt packages in a subdirectory scope
while using those Qt targets from a different scope.

E.g. it fixes errors like

  CMake Error at CMakeLists.txt:5 (target_link_libraries):
  Error evaluating generator expression:

    $<TARGET_OBJECTS:Qt6::Widgets_resources_1>

  Objects of target "Qt6::Widgets_resources_1" referenced but no such
  target exists.

when trying to use a static Qt from a sibling scope.

Various 3rd party dependency targets (like Atomic or ZLIB) are not
made global due to limitations in CMake, but as long as those targets
are not mentioned directly, it shouldn't cause issues.

The targets are made global in the generated
QtFooAdditionalTargetInfo.cmake file.

To ensure that resource object libraries promoted, the generation
of the file has to be done at the end of the defining scope
where qt_internal_export_additional_targets_file is called,
which is achieved with a deferred finalizer.

Replaced all occurrences of target promotion with a helper function
which allows tracing of all promoted targets by specifying
--log-level=debug to CMake.

Pick-to: 6.2
Fixes: QTBUG-92878
Change-Id: Ic4ec03b0bc383d7e591a58c520c3974fbea746d2
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
2021-06-16 13:22:17 +02:00

294 lines
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CMake
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# Add libraries to variable ${out_libs_var} in a way that duplicates
# are added at the end. This ensures the library order needed for the
# linker.
function(__qt_internal_merge_libs out_libs_var)
foreach(dep ${ARGN})
list(REMOVE_ITEM ${out_libs_var} ${dep})
list(APPEND ${out_libs_var} ${dep})
endforeach()
set(${out_libs_var} ${${out_libs_var}} PARENT_SCOPE)
endfunction()
# Extracts value from per-target dict key and assigns it to out_var.
# Assumes dict_name to be an existing INTERFACE target.
function(__qt_internal_get_dict_key_values out_var target_infix dict_name dict_key)
get_target_property(values "${dict_name}" "INTERFACE_${target_infix}_${dict_key}")
set(${out_var} "${values}" PARENT_SCOPE)
endfunction()
# Assigns 'values' to per-target dict key, including for aliases of the target.
# Assumes dict_name to be an existing INTERFACE target.
function(__qt_internal_memoize_values_in_dict target dict_name dict_key values)
# Memoize the computed values for the target as well as its aliases.
#
# Aka assigns the contents of ${values} to INTERFACE_Core, INTERFACE_Qt::Core,
# INTERFACE_Qt6::Core.
#
# Yes, i know it's crazy that target names are legal property names.
#
# Assigning for library aliases is needed to avoid multiple recomputation of values.
# Scenario in the context of __qt_internal_walk_libs:
# 'values' are computed for Core target and memoized to INTERFACE_Core.
# When processing Gui, it depends on Qt::Core, but there are no values for INTERFACE_Qt::Core.
set_target_properties(${dict_name} PROPERTIES INTERFACE_${target}_${dict_key} "${values}")
get_target_property(versionless_alias "${target}" "_qt_versionless_alias")
if(versionless_alias)
__qt_internal_get_dict_key_values(
versionless_values "${versionless_alias}" "${dict_name}" "${dict_key}")
if(versionless_values MATCHES "-NOTFOUND$")
set_target_properties(${dict_name}
PROPERTIES INTERFACE_${versionless_alias}_${dict_key} "${values}")
endif()
endif()
get_target_property(versionfull_alias "${target}" "_qt_versionfull_alias")
if(versionfull_alias)
__qt_internal_get_dict_key_values(
versionfull_values "${versionfull_alias}" "${dict_name}" "${dict_key}")
if(versionfull_values MATCHES "-NOTFOUND$")
set_target_properties(${dict_name}
PROPERTIES INTERFACE_${versionfull_alias}_${dict_key} "${values}")
endif()
endif()
endfunction()
# Walks a target's public link libraries recursively, and performs some actions (poor man's
# polypmorphism)
#
# Walks INTERFACE_LINK_LIBRARIES for all target types, as well as LINK_LIBRARIES for static
# library targets.
#
# out_var: the name of the variable where the result will be assigned. The result is a list of
# libraries, mostly in generator expression form.
# rcc_objects_out_var: the name of the variable where the collected rcc object files will be
# assigned (for the initial target and its dependencies)
# dict_name: used for caching the results, and preventing the same target from being processed
# twice
# operation: a string to tell the function what additional behaviors to execute.
# 'collect_libs' (default) operation is to collect linker file paths and flags.
# Used for prl file generation.
# 'promote_global' promotes walked imported targets to global scope.
# 'collect_targets' collects all target names (discards framework or link flags)
#
#
function(__qt_internal_walk_libs
target out_var rcc_objects_out_var dict_name operation)
set(collected ${ARGN})
if(target IN_LIST collected)
return()
endif()
list(APPEND collected ${target})
if(target STREQUAL "${QT_CMAKE_EXPORT_NAMESPACE}::EntryPointPrivate")
# We can't (and don't need to) process EntryPointPrivate because it brings in
# $<TARGET_PROPERTY:prop> genexes which get replaced with
# $<TARGET_PROPERTY:EntryPointPrivate,prop> genexes in the code below and that causes
# 'INTERFACE_LIBRARY targets may only have whitelisted properties.' errors with CMake
# versions equal to or lower than 3.18. These errors are super unintuitive to debug
# because there's no mention that it's happening during a file(GENERATE) call.
return()
endif()
if(NOT TARGET ${dict_name})
add_library(${dict_name} INTERFACE IMPORTED GLOBAL)
endif()
__qt_internal_get_dict_key_values(libs "${target}" "${dict_name}" "libs")
__qt_internal_get_dict_key_values(rcc_objects "${target}" "${dict_name}" "rcc_objects")
if(libs MATCHES "-NOTFOUND$")
unset(libs)
unset(rcc_objects)
get_target_property(target_libs ${target} INTERFACE_LINK_LIBRARIES)
if(NOT target_libs)
unset(target_libs)
endif()
get_target_property(target_type ${target} TYPE)
if(target_type STREQUAL "STATIC_LIBRARY")
get_target_property(link_libs ${target} LINK_LIBRARIES)
if(link_libs)
list(APPEND target_libs ${link_libs})
endif()
endif()
# Need to record the rcc object file info not only for dependencies, but also for
# the current target too. Otherwise the saved information is incomplete for prl static
# build purposes.
get_target_property(main_target_rcc_objects ${target} _qt_rcc_objects)
if(main_target_rcc_objects)
__qt_internal_merge_libs(rcc_objects ${main_target_rcc_objects})
endif()
foreach(lib ${target_libs})
# Cannot use $<TARGET_POLICY:...> in add_custom_command.
# Check the policy now, and replace the generator expression with the value.
while(lib MATCHES "\\$<TARGET_POLICY:([^>]+)>")
cmake_policy(GET ${CMAKE_MATCH_1} value)
if(value STREQUAL "NEW")
set(value "TRUE")
else()
set(value "FALSE")
endif()
string(REPLACE "${CMAKE_MATCH_0}" "${value}" lib "${lib}")
endwhile()
# Fix up $<TARGET_PROPERTY:FOO> expressions that refer to the "current" target.
# Those cannot be used with add_custom_command.
while(lib MATCHES "\\$<TARGET_PROPERTY:([^,>]+)>")
string(REPLACE "${CMAKE_MATCH_0}" "$<TARGET_PROPERTY:${target},${CMAKE_MATCH_1}>"
lib "${lib}")
endwhile()
# Skip static plugins.
set(_is_plugin_marker_genex "\\$<BOOL:QT_IS_PLUGIN_GENEX>")
if(lib MATCHES "${_is_plugin_marker_genex}")
continue()
endif()
# Strip any directory scope tokens.
__qt_internal_strip_target_directory_scope_token("${lib}" lib)
if(lib MATCHES "^\\$<TARGET_OBJECTS:")
# Skip object files.
continue()
elseif(lib MATCHES "^\\$<LINK_ONLY:(.*)>$")
set(lib_target ${CMAKE_MATCH_1})
else()
set(lib_target ${lib})
endif()
# Skip CMAKE_DIRECTORY_ID_SEP. If a target_link_libraries is applied to a target
# that was defined in a different scope, CMake appends and prepends a special directory
# id separator. Filter those out.
if(lib_target MATCHES "^::@")
continue()
elseif(TARGET ${lib_target})
if ("${lib_target}" MATCHES "^Qt::(.*)")
# If both, Qt::Foo and Foo targets exist, prefer the target name without
# namespace. Which one is preferred doesn't really matter. This code exists to
# avoid ending up with both, Qt::Foo and Foo in our dependencies.
set(namespaceless_lib_target "${CMAKE_MATCH_1}")
if(TARGET namespaceless_lib_target)
set(lib_target ${namespaceless_lib_target})
endif()
endif()
get_target_property(lib_target_type ${lib_target} TYPE)
if(lib_target_type STREQUAL "INTERFACE_LIBRARY")
__qt_internal_walk_libs(
${lib_target}
lib_libs_${target}
lib_rcc_objects_${target}
"${dict_name}" "${operation}" ${collected})
if(lib_libs_${target})
__qt_internal_merge_libs(libs ${lib_libs_${target}})
set(is_module 0)
endif()
if(lib_rcc_objects_${target})
__qt_internal_merge_libs(rcc_objects ${lib_rcc_objects_${target}})
endif()
elseif(NOT lib_target_type STREQUAL "OBJECT_LIBRARY")
if(operation STREQUAL "collect_targets")
__qt_internal_merge_libs(libs ${lib_target})
else()
__qt_internal_merge_libs(libs "$<TARGET_LINKER_FILE:${lib_target}>")
endif()
get_target_property(target_rcc_objects "${lib_target}" _qt_rcc_objects)
if(target_rcc_objects)
__qt_internal_merge_libs(rcc_objects ${target_rcc_objects})
endif()
__qt_internal_walk_libs(
${lib_target}
lib_libs_${target}
lib_rcc_objects_${target}
"${dict_name}" "${operation}" ${collected})
if(lib_libs_${target})
__qt_internal_merge_libs(libs ${lib_libs_${target}})
endif()
if(lib_rcc_objects_${target})
__qt_internal_merge_libs(rcc_objects ${lib_rcc_objects_${target}})
endif()
endif()
if(operation STREQUAL "promote_global")
set(lib_target_unaliased "${lib_target}")
get_target_property(aliased_target ${lib_target} ALIASED_TARGET)
if(aliased_target)
set(lib_target_unaliased ${aliased_target})
endif()
get_property(is_imported TARGET ${lib_target_unaliased} PROPERTY IMPORTED)
# Allow opting out of promotion. This is useful in certain corner cases
# like with WrapLibClang and Threads in qttools.
qt_internal_should_not_promote_package_target_to_global(
"${lib_target_unaliased}" should_not_promote)
if(is_imported AND NOT should_not_promote)
__qt_internal_promote_target_to_global(${lib_target_unaliased})
endif()
endif()
elseif("${lib_target}" MATCHES "^Qt::(.*)")
message(FATAL_ERROR "The ${CMAKE_MATCH_1} target is mentioned as a dependency for \
${target}, but not declared.")
else()
if(NOT operation STREQUAL "collect_targets")
set(final_lib_name_to_merge "${lib_target}")
if(lib_target MATCHES "/([^/]+).framework$")
set(final_lib_name_to_merge "-framework ${CMAKE_MATCH_1}")
endif()
__qt_internal_merge_libs(libs "${final_lib_name_to_merge}")
endif()
endif()
endforeach()
__qt_internal_memoize_values_in_dict("${target}" "${dict_name}" "libs" "${libs}")
__qt_internal_memoize_values_in_dict("${target}" "${dict_name}"
"rcc_objects" "${rcc_objects}")
endif()
set(${out_var} ${libs} PARENT_SCOPE)
set(${rcc_objects_out_var} ${rcc_objects} PARENT_SCOPE)
endfunction()
# Given ${target}, collect all its private dependencies that are CMake targets.
#
# Discards non-CMake-target dependencies like linker flags or file paths.
# Does nothing when given an interface library.
#
# To be used to extract the full list of target dependencies of a library or executable.
function(__qt_internal_collect_all_target_dependencies target out_var)
set(dep_targets "")
get_target_property(target_type ${target} TYPE)
if(NOT target_type STREQUAL "INTERFACE_LIBRARY")
get_target_property(link_libs ${target} LINK_LIBRARIES)
if(link_libs)
foreach(lib ${link_libs})
if(TARGET "${lib}")
list(APPEND dep_targets "${lib}")
__qt_internal_walk_libs(
"${lib}"
lib_walked_targets
_discarded_out_var
"qt_private_link_library_targets"
"collect_targets")
if(lib_walked_targets)
list(APPEND dep_targets ${lib_walked_targets})
endif()
endif()
endforeach()
endif()
endif()
list(REMOVE_DUPLICATES dep_targets)
set(${out_var} "${dep_targets}" PARENT_SCOPE)
endfunction()
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