cmake: Check if C++ compiler can compile ObjectiveC sources.

CMakeLists.txt

@@ -10,6 +10,39 @@ find_program(GIT git)
 find_program(RAGEL ragel)
 find_program(CONFETTI confetti)
 
+
+#
+# Check if CXX compiler can compile ObjectiveC sources.
+#  The code was borrowed from CMakeTestCXXCompiler.cmake
+#
+IF(NOT CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS)
+  MESSAGE(STATUS "Check for working CXX (ObjectiveC) compiler: ${CMAKE_CXX_COMPILER}")
+  FILE(WRITE ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/testCXXObjectiveCCompiler.m 
+    "int main(){return 0;}\n")
+  TRY_COMPILE(CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS ${CMAKE_BINARY_DIR} 
+    ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/testCXXObjectiveCCompiler.m
+    OUTPUT_VARIABLE OUTPUT)
+  SET(CXX_OBJECTIVEC_TEST_WAS_RUN 1)
+ENDIF(NOT CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS)
+IF(NOT CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS)
+  MESSAGE(STATUS "Check for working CXX (ObjectiveC) compiler: ${CMAKE_CXX_COMPILER} -- broken")
+  FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
+    "Determining if the CXX (ObjectiveC) compiler works failed with "
+    "the following output:\n${OUTPUT}\n\n")
+  MESSAGE(FATAL_ERROR "The C++ compiler \"${CMAKE_CXX_COMPILER}\" "
+    "is not able to compile a simple ObjectiveC test program.\nIt fails "
+    "with the following output:\n ${OUTPUT}\n\n"
+    "CMake will not be able to correctly generate this project.")
+ELSE(NOT CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS)
+  IF(CXX_OBJECTIVEC_TEST_WAS_RUN)
+    MESSAGE(STATUS "Check for working CXX (ObjectiveC) compiler: ${CMAKE_CXX_COMPILER} -- works")
+    FILE(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
+      "Determining if the CXX (ObjectiveC) compiler works passed with "
+      "the following output:\n${OUTPUT}\n\n")
+  ENDIF(CXX_OBJECTIVEC_TEST_WAS_RUN)
+  SET(CMAKE_CXX_OBJETIVEC_COMPILER_WORKS 1 CACHE INTERNAL "")
+ENDIF(NOT CMAKE_CXX_OBJECTIVEC_COMPILER_WORKS)
+
 #
 # This instructs the rest of the build system what product
 # and what modules to produce.