Added -Werror to demos project

util/test/demos/CMakeLists.txt

@@ -107,6 +107,9 @@ project(demos)
 
 if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
     set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
+    list(APPEND warning_flags -Werror)
+    string(REPLACE ";" " " warning_flags "${warning_flags}")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${warning_flags}")
 endif()
 
 if(NOT APPLE AND UNIX)