[boost] Unescaped special character in argument <cxx, flags>/std:c++nn

Subject: [boost] Unescaped special character in argument <cxx, flags>/std:c++nn
From: Edward Diener (eldiener_at_[hidden])
Date: 2018-03-26 19:53:38

When compiling with vc++ and specifying in my user_config.jam file:

using msvc : 14.1c14 : : <cxxflags>/std:c++14 ;
using msvc : 14.1c17 : : <cxxflags>/std:c++latest ;

I am getting the messages:

user-config.jam:5: Unescaped special character in argument 
<cxxflags>/std:c++14
user-config.jam:6: Unescaped special character in argument 
<cxxflags>/std:c++latest

I am using the latest 'develop' branch of Boost Build.

What is the workaround for this ?