cmake: correct version dependency for qt5_add_big_resources

qt5_add_big_resources is only available if using CMake 3.9 and later.

This amends cdccd0222b.

Task-number: QTBUG-55680
Task-number: QTBUG-75806
Change-Id: Ibba7af6ee7edfb226368937d543b7ec5cc93eb16
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Kai Koehne <kai.koehne@qt.io>

src/corelib/Qt5CoreMacros.cmake

@@ -296,6 +296,9 @@ endfunction()
 # qt5_add_big_resources(outfiles inputfile ... )
 
 function(QT5_ADD_BIG_RESOURCES outfiles )
+    if (CMAKE_VERSION VERSION_LESS 3.9)
+        message(FATAL_ERROR, "qt5_add_big_resources requires CMake 3.9 or newer")
+    endif()
 
     set(options)
     set(oneValueArgs)
@@ -326,6 +329,8 @@ function(QT5_ADD_BIG_RESOURCES outfiles )
         set_target_properties(rcc_object_${outfilename} PROPERTIES AUTOMOC OFF)
         set_target_properties(rcc_object_${outfilename} PROPERTIES AUTOUIC OFF)
         add_dependencies(rcc_object_${outfilename} big_resources_${outfilename})
+        # The modification of TARGET_OBJECTS needs the following change in cmake
+        # https://gitlab.kitware.com/cmake/cmake/commit/93c89bc75ceee599ba7c08b8fe1ac5104942054f
         add_custom_command(OUTPUT ${outfile}
                            COMMAND ${Qt5Core_RCC_EXECUTABLE}
                            ARGS ${rcc_options} --name ${outfilename} --pass 2 --temp $<TARGET_OBJECTS:rcc_object_${outfilename}> --output ${outfile} ${infile}

src/corelib/doc/src/cmake-macros.qdoc

@@ -131,6 +131,8 @@ files (\c .o, \c .obj) files instead of C++ source code. This allows to
 embed bigger resources, where compiling to C++ sources and then to
 binaries would be too time consuming or memory intensive.
 
+Note that this macro is only available if using \c{CMake} 3.9 or later.
+
 \section1 Arguments
 
 You can set additional \c{OPTIONS} that should be added to the \c{rcc} calls.

tests/auto/cmake/CMakeLists.txt

@@ -146,7 +146,12 @@ endif()
 
 expect_pass(test_interface_link_libraries)
 expect_pass(test_moc_macro_target)
-expect_pass(test_add_big_resource)
+
+if (NOT CMAKE_VERSION VERSION_LESS 3.9)
+    # The modification of TARGET_OBJECTS needs the following change in cmake
+    # https://gitlab.kitware.com/cmake/cmake/commit/93c89bc75ceee599ba7c08b8fe1ac5104942054f
+    expect_pass(test_add_big_resource)
+endif()
 
 if (NOT CMAKE_VERSION VERSION_LESS 3.8)
     # With earlier CMake versions, this test would simply run moc multiple times and lead to:

tests/auto/cmake/test_add_big_resource/CMakeLists.txt

@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8)
+cmake_minimum_required(VERSION 3.9)
 
 project(test_add_big_resource)