quicktype: C++ code generated by quicktype does not compile in Visual Studio 2017 when "conformance mode" is off

I have generated C++ code from JSON Schema “Coordinate” and tried compiling it with VS 15.7.6. It turned out that if you set “Conformance mode” to “No”, it doesn’t compile. I have attached the sample project and a screenshot of the said option. The error is as follows:

1>------ Build started: Project: quicktype_compilation, Configuration: Debug Win32 ------
1>stdafx.cpp
1>quicktype_compilation.cpp
1>s:\quicktype_compilation\quicktype_compilation\vd_json_serializer.h(18): error C2679: binary '=': no operator found which takes a right-hand operand of type 'double' (or there is no acceptable conversion)
...

You can see it yourself when compiling my project.

quicktype_compilation.zip