Revert 883f5ebf6bc2af2decd4e64aeda1ee92bff40e54 and fix it.

Unfortunately that commit was wrong. Compilation tests need to link
to QtCore in order to resolve qt_assert, which is used indirectly.
This commit reverts and fixes the original problem in a different way,
using handle_imported_targets_in_cmake_required_libraries()

3 files changed, 94 insertions, 1 deletions

diff --git a/cmake/modules/FindQt4or5.cmake b/cmake/modules/FindQt4or5.cmake
index f5355b2..b0f6874 100644
--- a/cmake/modules/FindQt4or5.cmake
+++ b/cmake/modules/FindQt4or5.cmake
@@ -177,6 +177,13 @@ include(FindPackageHandleStandardArgs)
 find_package_handle_standard_args(Qt4or5 REQUIRED_VARS _Qt4or5_FOUND HANDLE_COMPONENTS)
 set(Qt4or5_FOUND ${QT4OR5_FOUND})
 
+# Core library needed for compilation tests
+if (${QT_VERSION} STREQUAL "4")
+  set (Qt4or5_Core_LIBRARIES ${QT_QTCORE_LIBRARY})
+else()
+  set (Qt4or5_Core_LIBRARIES ${Qt5Core_LIBRARIES})
+endif()
+
 # qt4or5_use_modules(target [ LINK_PUBLIC | LINK_PRIVATE ] <modules>)
 # Supported modules: Core, Gui, Widgets, Quick1, Quick2, Test, OpenGL
 function(qt4or5_use_modules _target _link_type)
diff --git a/cmake/modules/HandleImportedTargetsInCMakeRequiredLibraries.cmake b/cmake/modules/HandleImportedTargetsInCMakeRequiredLibraries.cmake
new file mode 100644
index 0000000..10b6806
--- /dev/null
+++ b/cmake/modules/HandleImportedTargetsInCMakeRequiredLibraries.cmake
@@ -0,0 +1,83 @@
+# This is a helper function used by CheckCXXSourceRuns.cmake and
+# CheckCXXSourceCompiles.cmake. Actually it should be used by all macros which
+# use TRY_COMPILE() or TRY_RUN().
+# It takes the CMAKE_REQUIRED_LIBRARY variable and searches it for imported
+# (library) targets. Since the project created by TRY_COMPILE() (and TRY_RUN())
+# does not know about these imported targets, this macro here replaces these
+# imported targets with the actual library files on disk and it also
+# adds the libraries from the link interface of these imported targets.
+# E.g the imported target KDE4__kdeui is replaced on my system with /opt/kdelibs/lib/libkdeui.so
+# and the link interface libraries, which includes e.g. /opt/kdelibs/lib/libkdecore.so.
+# This way imported targets work also when used with CHECK_CXX_SOURCE_COMPILES/RUNS().
+
+# Copyright (c) 2009, Alexander Neundorf, <neundorf@kde.org>
+#
+# Redistribution and use is allowed according to the terms of the BSD license.
+# For details see the accompanying COPYING-CMAKE-SCRIPTS file.
+
+FUNCTION(HANDLE_IMPORTED_TARGETS_IN_CMAKE_REQUIRED_LIBRARIES _RESULT)
+# handle imported library targets
+   SET(_CCSR_IMP_TARGETS_MAP)
+   SET(_CCSR_REQ_LIBS ${CMAKE_REQUIRED_LIBRARIES})
+   SET(_CHECK_FOR_IMPORTED_TARGETS TRUE)
+   SET(_CCSR_LOOP_COUNTER 0)
+   WHILE(_CHECK_FOR_IMPORTED_TARGETS)
+      MATH(EXPR _CCSR_LOOP_COUNTER "${_CCSR_LOOP_COUNTER} + 1 ")
+      SET(_CCSR_NEW_REQ_LIBS )
+      SET(_CHECK_FOR_IMPORTED_TARGETS FALSE)
+      FOREACH(_CURRENT_LIB ${_CCSR_REQ_LIBS})
+         GET_TARGET_PROPERTY(_importedConfigs ${_CURRENT_LIB} IMPORTED_CONFIGURATIONS)
+         IF (_importedConfigs)
+            # Ok, so this is an imported target.
+            # First we get the imported configurations.
+            # Then we get the location of the actual library on disk of the first configuration.
+            # then we'll get its link interface libraries property,
+            # iterate through it and replace all imported targets we find there
+            # with there actual location.
+
+            # guard against infinite loop: abort after 100 iterations ( 100 is arbitrary chosen)
+            IF ("${_CCSR_LOOP_COUNTER}" LESS 100)
+               SET(_CHECK_FOR_IMPORTED_TARGETS TRUE)
+#                ELSE ("${_CCSR_LOOP_COUNTER}" LESS 1)
+#                   MESSAGE(STATUS "********* aborting loop, counter : ${_CCSR_LOOP_COUNTER}")
+            ENDIF ("${_CCSR_LOOP_COUNTER}" LESS 100)
+
+            LIST(GET _importedConfigs 0 _firstImportedConfig)
+            GET_TARGET_PROPERTY(_firstImportedLocation ${_CURRENT_LIB} IMPORTED_LOCATION_${_firstImportedConfig})
+            GET_TARGET_PROPERTY(_linkInterfaceLibs ${_CURRENT_LIB} IMPORTED_LINK_INTERFACE_LIBRARIES_${_firstImportedConfig} )
+
+            LIST(APPEND _CCSR_NEW_REQ_LIBS  ${_firstImportedLocation})
+#                MESSAGE(STATUS "Appending lib ${_CURRENT_LIB} as ${_firstImportedLocation}")
+            IF(_linkInterfaceLibs)
+               FOREACH(_currentLinkInterfaceLib ${_linkInterfaceLibs})
+#                   MESSAGE(STATUS "Appending link interface lib ${_currentLinkInterfaceLib}")
+                  IF(_currentLinkInterfaceLib)
+                     LIST(APPEND _CCSR_NEW_REQ_LIBS ${_currentLinkInterfaceLib} )
+                  ENDIF(_currentLinkInterfaceLib)
+               ENDFOREACH(_currentLinkInterfaceLib ${_linkInterfaceLibs})
+            ENDIF(_linkInterfaceLibs)
+         ELSE(_importedConfigs)
+            # "Normal" libraries are just used as they are.
+            LIST(APPEND _CCSR_NEW_REQ_LIBS ${_CURRENT_LIB} )
+#                MESSAGE(STATUS "Appending lib directly: ${_CURRENT_LIB}")
+         ENDIF(_importedConfigs)
+      ENDFOREACH(_CURRENT_LIB ${_CCSR_REQ_LIBS})
+
+      SET(_CCSR_REQ_LIBS ${_CCSR_NEW_REQ_LIBS} )
+   ENDWHILE(_CHECK_FOR_IMPORTED_TARGETS)
+
+   # Finally we iterate once more over all libraries. This loop only removes
+   # all remaining imported target names (there shouldn't be any left anyway).
+   SET(_CCSR_NEW_REQ_LIBS )
+   FOREACH(_CURRENT_LIB ${_CCSR_REQ_LIBS})
+      GET_TARGET_PROPERTY(_importedConfigs ${_CURRENT_LIB} IMPORTED_CONFIGURATIONS)
+      IF (NOT _importedConfigs)
+         LIST(APPEND _CCSR_NEW_REQ_LIBS ${_CURRENT_LIB} )
+#             MESSAGE(STATUS "final: appending ${_CURRENT_LIB}")
+      ELSE (NOT _importedConfigs)
+#             MESSAGE(STATUS "final: skipping ${_CURRENT_LIB}")
+      ENDIF (NOT _importedConfigs)
+   ENDFOREACH(_CURRENT_LIB ${_CCSR_REQ_LIBS})
+   SET(${_RESULT} ${_CCSR_NEW_REQ_LIBS} PARENT_SCOPE)
+
+ENDFUNCTION(HANDLE_IMPORTED_TARGETS_IN_CMAKE_REQUIRED_LIBRARIES _RESULT)
diff --git a/tests/compilation/CompilationTests_CMakeLists.txt b/tests/compilation/CompilationTests_CMakeLists.txt
index 165d80a..ccfc865 100644
--- a/tests/compilation/CompilationTests_CMakeLists.txt
+++ b/tests/compilation/CompilationTests_CMakeLists.txt
@@ -11,7 +11,7 @@ find_package(Qt4or5 COMPONENTS Core REQUIRED)
 include(QtGStreamerConfigCommon)
 include(MacroCXXCompilationTest)
 
-set(CMAKE_REQUIRED_LIBRARIES ${QTGSTREAMER_LIBRARY} ${QTGLIB_LIBRARY})
+set(CMAKE_REQUIRED_LIBRARIES ${QTGSTREAMER_LIBRARY} ${QTGLIB_LIBRARY} ${Qt4or5_Core_LIBRARIES})
 set(CMAKE_REQUIRED_INCLUDES ${QTGSTREAMER_INCLUDES})
 set(CMAKE_REQUIRED_DEFINITIONS ${QTGSTREAMER_DEFINITIONS})
 set(CMAKE_REQUIRED_FLAGS "${QTGSTREAMER_FLAGS}")
@@ -24,6 +24,9 @@ if (QTGSTREAMER_STATIC)
                                  ${GSTREAMER_INTERFACES_LIBRARY})
 endif()
 
+include(HandleImportedTargetsInCMakeRequiredLibraries)
+handle_imported_targets_in_cmake_required_libraries(CMAKE_REQUIRED_LIBRARIES)
+
 message("********* Begin running compilation tests *********")
 include(CompilationTests.cmake)
 evaluate_cxx_compilation_test_results()