ncm2-syntax is syntax source for NCM2, it depends on Shougo/neco-syntax
neco-syntax gathers syntax data from vim syntax file. This plugin will use these data as the source of ncm2 for completion.
ncm2-syntax is out-of-box with zero config.
The completion item with mark [syntax]
is provided by ncm2-syntax.
Assuming that you are using vim-plug
Plug 'ncm2/ncm2-syntax' | Plug 'Shougo/neco-syntax'
Here is a short demo