std::variant not found

[Pfeifenjoy]

Problems summary

I want to use std::variant from c++17.
This however does not seem to work.
I always get "no template named 'variant' in namespace 'std'" when I run ALEDetail.

Environment Information

• OS: OSX
• Neovim version: NVIM v0.3.1

Provide a minimal init.vim with less than 50 lines and not plugin manager (Required!)

" Your minimal init.vim
Plug 'Shougo/deoplete.nvim'
Plug 'zchee/deoplete-clang'

let g:deoplete#sources#clang#std = 'c++17'