Disable -Wdouble-promotion for GCC 4.5.

src/CMakeLists.txt

@@ -1,9 +1,5 @@
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wold-style-cast -pedantic -std=c++0x -fvisibility=hidden")
 
-if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wdouble-promotion")
-endif()
-
 # If targeting GLES, save it into configuration header
 if(TARGET_GLES)
     set(MAGNUM_TARGET_GLES 1)
@@ -18,6 +14,14 @@ if(GCC45_COMPATIBILITY)
     set(MAGNUM_GCC45_COMPATIBILITY 1)
 endif()
 
+# -Wdouble-promotion is supported from GCC 4.6
+# TODO: do this with check_c_compiler_flags()
+if(NOT GCC45_COMPATIBILITY)
+    if("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+        set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wdouble-promotion")
+    endif()
+endif()
+
 configure_file(${CMAKE_CURRENT_SOURCE_DIR}/magnumConfigure.h.cmake
                ${CMAKE_CURRENT_BINARY_DIR}/magnumConfigure.h)