CMake: introduce copy_target_properties() macro

This macro is used to copy target properties from imported targets
recursively into our interface targets. This will allow us to modernize
our configure_<feature> macros to use imported targets directly instead
of extracting all of this information for each external feature.

diff --git a/cmake/macros/macro_copy_target_properties.cmake b/cmake/macros/macro_copy_target_properties.cmake
new file mode 100644 (file)
index 0000000..4834bf0
--- /dev/null
+++ b/cmake/macros/macro_copy_target_properties.cmake
@@ -0,0 +1,140 @@
+## ---------------------------------------------------------------------
+##
+## Copyright (C) 2022 - 2022 by the deal.II authors
+##
+## This file is part of the deal.II library.
+##
+## The deal.II library is free software; you can use it, redistribute
+## it, and/or modify it under the terms of the GNU Lesser General
+## Public License as published by the Free Software Foundation; either
+## version 2.1 of the License, or (at your option) any later version.
+## The full text of the license can be found in the file LICENSE.md at
+## the top level directory of deal.II.
+##
+## ---------------------------------------------------------------------
+
+#
+# copy_target_properties(<destination target> [<source targets>])
+#
+# Copies relevant (imported) target properties from the source targets and
+# appends the properties to the destination target.
+#
+
+function(copy_target_properties _destination_target)
+
+  #
+  # Make sure that we expand all targets recursively for the sake of a
+  # cleaner output we check whether we have already included a given target
+  #
+
+  set(_source_targets ${ARGN})
+  set(_processed_targets)
+
+  #
+  # Collect values over all targets found in ${_source_targets}:
+  #
+
+  set(_libraries)
+  set(_include_directories)
+  set(_compile_definitions)
+  set(_compile_options)
+  set(_link_options)
+
+  while(NOT "${_source_targets}" STREQUAL "")
+    # Future FIXME: replace by POP_FRONT (CMake 3.15)
+    list(GET _source_targets 0 _entry)
+    list(REMOVE_AT _source_targets 0)
+
+    if(${_entry} IN_LIST _processed_targets)
+      continue()
+    endif()
+
+    list(APPEND _processed_targets ${_entry})
+    message(STATUS "    copying ${_entry} into ${_destination_target} ...")
+
+    get_target_property(_location ${_entry} IMPORTED_LOCATION)
+    if("${_location}" MATCHES "-NOTFOUND")
+      set(_location)
+    endif()
+
+    get_target_property(_values ${_entry} INTERFACE_LINK_LIBRARIES)
+    if("${_values}" MATCHES "-NOTFOUND")
+      set(_values)
+    endif()
+
+    foreach(_lib ${_location} ${_values})
+      if(TARGET ${_lib})
+        list(APPEND _source_targets ${_lib})
+      else()
+        # Warn loudly if we encounter an undefined target:
+        if("${_lib}" MATCHES "::")
+          message(WARNING
+            "Undefined imported target name »${_lib}« present in interface "
+            "of target »${_entry}«"
+            )
+        endif()
+        list(APPEND _libraries ${_entry})
+      endif()
+    endforeach()
+
+    get_target_property(_values ${_entry} INTERFACE_INCLUDE_DIRECTORIES)
+    if(NOT "${_values}" MATCHES "-NOTFOUND")
+      list(APPEND _include_directories ${_values})
+    endif()
+
+    get_target_property(_values ${_entry} INTERFACE_SYSTEM_INCLUDE_DIRECTORIES)
+    if(NOT "${_values}" MATCHES "-NOTFOUND")
+      list(APPEND _include_directories ${_values})
+    endif()
+
+    get_target_property(_values ${_entry} INTERFACE_COMPILE_DEFINITIONS)
+    if(NOT "${_values}" MATCHES "-NOTFOUND")
+      list(APPEND _compile_definitions ${_values})
+    endif()
+
+    get_target_property(_values ${_entry} INTERFACE_COMPILE_OPTIONS)
+    if(NOT "${_values}" MATCHES "-NOTFOUND")
+      list(APPEND _compile_options ${_values})
+    endif()
+
+    get_target_property(_values ${_entry} INTERFACE_LINK_OPTIONS)
+    if(NOT "${_values}" MATCHES "-NOTFOUND")
+      list(APPEND _link_options ${_values})
+    endif()
+  endwhile()
+
+  #
+  # Populate destination target:
+  #
+
+  if(NOT "${_libraries}" STREQUAL "")
+    remove_duplicates(_libraries REVERSE)
+    message(STATUS "    LINK_LIBRARIES:      ${_libraries}")
+    target_link_libraries(${_destination_target} INTERFACE ${_libraries})
+  endif()
+
+  if(NOT "${_include_directories}" STREQUAL "")
+    remove_duplicates(_include_directories)
+    message(STATUS "    INCLUDE_DIRECTORIES: ${_include_directories}")
+    target_include_directories(${_destination_target} SYSTEM INTERFACE ${_include_directories})
+  endif()
+
+  if(NOT "${_compile_definitions}" STREQUAL "")
+    remove_duplicates(_compile_definitions REVERSE)
+    message(STATUS "    COMPILE_DEFINITIONS: ${_compile_definitions}")
+    target_compile_definitions(${_destination_target} INTERFACE ${_compile_definitions})
+  endif()
+
+  if(NOT "${_compile_options}" STREQUAL "")
+    remove_duplicates(_compile_options REVERSE)
+    message(STATUS "    COMPILE_OPTIONS: ${_compile_options}")
+    target_compile_options(${_destination_target} INTERFACE ${_compile_options})
+  endif()
+
+  if(NOT "${_link_options}" STREQUAL "")
+    remove_duplicates(_link_options REVERSE)
+    message(STATUS "    LINK_OPTIONS: ${_link_options}")
+    target_compile_options(${_destination_target} INTERFACE ${_link_options})
+  endif()
+endfunction()
+

diff --git a/cmake/macros/macro_define_interface_target.cmake b/cmake/macros/macro_define_interface_target.cmake
index 85ff8da600b37c684391b55a5edf0438f03a223d..afa17aabc3f1be80c6a205645ef0cc5160f2f008 100644 (file)
--- a/cmake/macros/macro_define_interface_target.cmake
+++ b/cmake/macros/macro_define_interface_target.cmake
@@ -90,7 +90,6 @@ function(define_interface_target _feature)
     set(_libraries)
     list(APPEND _libraries
       ${${_feature}_LIBRARIES} ${${_feature}_LIBRARIES_${_build}}
-      ${${_feature}_TARGETS} ${${_feature}_TARGETS_${_build}}
       )
     if(NOT "${_libraries}" STREQUAL "")
       message(STATUS "    LINK_LIBRARIES:      ${_libraries}")
@@ -129,6 +128,12 @@ function(define_interface_target _feature)
       target_link_options(${_interface_target} INTERFACE ${_link_options})
     endif()
 
+    if(NOT "${${_feature}_TARGETS}${${_feature}_TARGETS_${_build}}" STREQUAL "")
+      set(_targets ${${_feature}_TARGETS}${${_feature}_TARGETS_${_build}})
+      message(STATUS "    IMPORTED TARGETS:    ${_targets}")
+      copy_target_properties(${_interface_target} ${${_feature}_TARGETS} ${${_feature}_TARGETS_${_build}})
+    endif()
+
     export(TARGETS ${_interface_target}
       NAMESPACE "${DEAL_II_TARGET_NAME}::"
       FILE ${CMAKE_BINARY_DIR}/${DEAL_II_PROJECT_CONFIG_RELDIR}/${DEAL_II_PROJECT_CONFIG_NAME}Targets.cmake