Add comments about warning flags

CMake/README.md

@@ -44,6 +44,11 @@
       set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++ ${CMAKE_CXX_FLAGS}")
 
       if (MSVC)
+        # /wd4005  macro-redefinition
+        # /wd4068  unknown pragma
+        # /wd4244  conversion from 'type1' to 'type2'
+        # /wd4267  conversion from 'size_t' to 'type2'
+        # /wd4800  force value to bool 'true' or 'false' (performance warning)
         add_compile_options(/wd4005 /wd4068 /wd4244 /wd4267 /wd4800)
         add_definitions(/DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS)
       endif()

CMakeLists.txt

@@ -27,8 +27,13 @@ include(AbseilHelpers)
 
 # config options
 if (MSVC)
-  add_definitions(/DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS)
+  # /wd4005  macro-redefinition
+  # /wd4068  unknown pragma
+  # /wd4244  conversion from 'type1' to 'type2'
+  # /wd4267  conversion from 'size_t' to 'type2'
+  # /wd4800  force value to bool 'true' or 'false' (performance warning)
   add_compile_options(/W3 /WX /wd4005 /wd4068 /wd4244 /wd4267 /wd4800)
+  add_definitions(/DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS)
 else()
   set(ABSL_STD_CXX_FLAG "-std=c++11" CACHE STRING "c++ std flag (default: c++11)")
 endif()