Treat all compiler warnings as errors

CMakeLists.txt

@@ -190,9 +190,9 @@ if(MSVC)
   else()
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W4")
   endif()
-elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
+elseif(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   # Update if necessary
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wno-sign-compare -Wno-reorder")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Werror -Wno-sign-compare -Wno-reorder")
 endif()
 
 CHECK_CXX_COMPILER_FLAG("-stdlib=libc++" COMPILER_SUPPORTS_LIBCPP)