```cmake
if(CMAKE_COMPILER_IS_GNUCXX)
  set(CMAKE_CXX_FLAGS "-fPIC ${CMAKE_CXX_FLAGS}")
elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
  set(CMAKE_CXX_FLAGS "-fPIC ${CMAKE_CXX_FLAGS}")
  if(${CMAKE_SYSTEM_NAME} STREQUAL "Darwin" OR USE_LIBCPP)
    find_library(LIBCPP NAMES libc++.so libc++.so.1.0 libc++.dylib OPTIONAL)
    if(LIBCPP)
      message(STATUS "Using native Clang's C++ standard library: ${LIBCPP}")
      set(CMAKE_CXX_FLAGS "-stdlib=libc++ ${CMAKE_CXX_FLAGS}")
      add_definitions("-DHAVELIBCPP")
    endif()
  endif()
elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
  set(CMAKE_CXX_FLAGS "-D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS ${CMAKE_CXX_FLAGS}")
  add_definitions("-DUNICODE -D_UNICODE")
endif(CMAKE_COMPILER_IS_GNUCXX)
```

Disable MSVC warnings for C code as well as C++
user
```cmake
if(CMAKE_COMPILER_IS_GNUCXX)
  set(CMAKE_CXX_FLAGS "-fPIC ${CMAKE_CXX_FLAGS}")
elseif(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
  set(CMAKE_CXX_FLAGS "-fPIC ${CMAKE_CXX_FLAGS}")
  if(${CMAKE_SYSTEM_NAME} STREQUAL "Darwin" OR USE_LIBCPP)
    find_library(LIBCPP NAMES libc++.so libc++.so.1.0 libc++.dylib OPTIONAL)
    if(LIBCPP)
      message(STATUS "Using native Clang's C++ standard library: ${LIBCPP}")
      set(CMAKE_CXX_FLAGS "-stdlib=libc++ ${CMAKE_CXX_FLAGS}")
      add_definitions("-DHAVELIBCPP")
    endif()
  endif()
elseif("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
  set(CMAKE_CXX_FLAGS "-D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS ${CMAKE_CXX_FLAGS}")
  set(CMAKE_C_FLAGS "-D_SCL_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_WARNINGS ${CMAKE_C_FLAGS}")
  add_definitions("-DUNICODE -D_UNICODE")
endif(CMAKE_COMPILER_IS_GNUCXX)
```
assistant