vs2015 error : static member will remain uninitialized at runtime but use in constant-expressions is supported

[xtythansky]

on some vs2015 occurs
`json.hpp(887): error C4579: 'nlohmann::detail::static_constnlohmann::detail::to_json_fn::value': in-class initialization for type 'const T' is not yet implemented; static member will remain uninitialized at runtime but use in constant-expressions is supported
with
[
T=nlohmann::detail::to_json_fn
]

`

[gregmarr]

This, I believe, fixed in Update 3.