Update C++ version and use newer Windows SDK (#683)

Author: a-maurice

CMakeLists.txt

@@ -16,7 +16,8 @@
 
 # Higher CMake version needed for improvments in UseSwig.cmake and string join
 cmake_minimum_required (VERSION 3.13.4)
-set (CMAKE_CXX_STANDARD 11)
+set (CMAKE_CXX_STANDARD 14)
+set (CMAKE_CXX_STANDARD_REQUIRED YES) # Don't fall back to an earlier version.
 
 # Turn on virtual folders for visual studio
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)

scripts/build_scripts/build_zips.py

@@ -433,6 +433,9 @@ def get_windows_args():
   result_args.append('-G Visual Studio 16 2019')
   result_args.append('-A x64') # TODO flexibily for x32
   result_args.append("-DFIREBASE_PYTHON_HOST_EXECUTABLE:FILEPATH=%s" % sys.executable)
+  # Use a newer version of the Windows SDK, as the default one has build issues with grpc
+  if FLAGS.gha:
+    result_args.append('-DCMAKE_SYSTEM_VERSION=10.0.20348.0')
   return result_args
 
 def get_macos_args():