How to use omnisharp-vim with latest omnisharp-roslyn

.vimrc

"All user-dependent configurations are omitted intentionally.
"This gist only includes configurations for omnisharp.
"Original vimrc is available on:
"https://github.com/OmniSharp/omnisharp-vim#example-vimrc

"=========================================================
" **Preparation steps
"1. Install pathogen.vim or preferred plugin manager
"(Will explain procedures with assumption that a user is using pathogen.vim)
" **Main steps
"1. Clone omnisharp-vim into $HOME/.vim/bundle (if the folder does not exist, you can safely create it)
"2. Clone omnisharp-roslyn into your favorite place
"3. Install mono and dotnet-core by following offical document written by Mono project:
"   http://www.mono-project.com/download/stable/#download-lin
"4. Install nuget and msbuild (should be installed due to dependency)
"5. Get into omnisharp-roslyn repository folder and run 'build.sh'
"6. When the build succeeds, configure your .vimrc (_vimrc on Windows) using below examples.
"   DO NOT FORGET TO CHANGE THE PATH OF OMNISHARP SERVER IN EXAMPLE
"   SINCE I HAVE HARD-CODED IT 
" **How to test (the project name is testproject but it varies what a user wants)
"1. Since new .NET project and its solution file (.sln) are required, Run from shell,
"  $ dotnet new console -n testproject
"  $ cd testproject && dotnet new sln
"2. Open testproject.sln and add PROJECT statemnets (important, below one is an example)
"   Project("TEST") = "HelloWorld", "HelloWorld.csproj", "TEST"
"3. Open Program.cs and start to test features of omnisharp-vim
"  $ vim Program.cs
"2. After writing test code like printing Hello World!, run your test project by typing,
"  $ cd testproject && dotnet run
"=========================================================
"=========================================================
"---- configuration starts from here ----
"=========================================================
"OmniSharp won't work without this setting
filetype plugin on

"This is the default value, setting it isn't actually necessary
let g:OmniSharp_host = "http://localhost:2000"

"Set to manually compiled OmniSharp.exe server (from omnisharp-roslyn)
"XXX: must be modified.
let g:OmniSharp_server_path = "/home/nidev/omnisharp-roslyn/bin/Release/OmniSharp.Http/net46/OmniSharp.exe"

"Set the type lookup function to use the preview window instead of the status line
"let g:OmniSharp_typeLookupInPreview = 1

"Timeout in seconds to wait for a response from the server
let g:OmniSharp_timeout = 1

"Showmatch significantly slows down omnicomplete
"when the first match contains parentheses.
set noshowmatch

"Super tab settings - uncomment the next 4 lines
let g:SuperTabDefaultCompletionType = 'context'
let g:SuperTabContextDefaultCompletionType = "<c-x><c-o>"
let g:SuperTabDefaultCompletionTypeDiscovery = ["&omnifunc:<c-x><c-o>","&completefunc:<c-x><c-n>"]
let g:SuperTabClosePreviewOnPopupClose = 1

"don't autoselect first item in omnicomplete, show if only one item (for preview)
"remove preview if you don't want to see any documentation whatsoever.
set completeopt=longest,menuone,preview
"set completeopt-=preview

" Fetch full documentation during omnicomplete requests.
" There is a performance penalty with this (especially on Mono)
" By default, only Type/Method signatures are fetched. Full documentation can still be fetched when
" you need it with the :OmniSharpDocumentation command.
" let g:omnicomplete_fetch_full_documentation=1

"Move the preview window (code documentation) to the bottom of the screen, so it doesn't move the code!
"You might also want to look at the echodoc plugin
set splitbelow

" Get Code Issues and syntax errors
let g:syntastic_cs_checkers = ['syntax', 'semantic', 'issues']
" If you are using the omnisharp-roslyn backend, use the following
" let g:syntastic_cs_checkers = ['code_checker']
augroup omnisharp_commands
    autocmd!

    "Set autocomplete function to OmniSharp (if not using YouCompleteMe completion plugin)
    autocmd FileType cs setlocal omnifunc=OmniSharp#Complete

    " Synchronous build (blocks Vim)
    "autocmd FileType cs nnoremap <F5> :wa!<cr>:OmniSharpBuild<cr>
    " Builds can also run asynchronously with vim-dispatch installed
    autocmd FileType cs nnoremap <leader>b :wa!<cr>:OmniSharpBuildAsync<cr>
    " automatic syntax check on events (TextChanged requires Vim 7.4)
    autocmd BufEnter,TextChanged,InsertLeave *.cs SyntasticCheck

    " Automatically add new cs files to the nearest project on save
    autocmd BufWritePost *.cs call OmniSharp#AddToProject()

    "show type information automatically when the cursor stops moving
    autocmd CursorHold *.cs call OmniSharp#TypeLookupWithoutDocumentation()

    "The following commands are contextual, based on the current cursor position.

    autocmd FileType cs nnoremap gd :OmniSharpGotoDefinition<cr>
    autocmd FileType cs nnoremap <leader>fi :OmniSharpFindImplementations<cr>
    autocmd FileType cs nnoremap <leader>ft :OmniSharpFindType<cr>
    autocmd FileType cs nnoremap <leader>fs :OmniSharpFindSymbol<cr>
    autocmd FileType cs nnoremap <leader>fu :OmniSharpFindUsages<cr>
    "finds members in the current buffer
    autocmd FileType cs nnoremap <leader>fm :OmniSharpFindMembers<cr>
    " cursor can be anywhere on the line containing an issue
    autocmd FileType cs nnoremap <leader>x  :OmniSharpFixIssue<cr>
    autocmd FileType cs nnoremap <leader>fx :OmniSharpFixUsings<cr>
    autocmd FileType cs nnoremap <leader>tt :OmniSharpTypeLookup<cr>
    autocmd FileType cs nnoremap <leader>dc :OmniSharpDocumentation<cr>
    "navigate up by method/property/field
    autocmd FileType cs nnoremap <C-K> :OmniSharpNavigateUp<cr>
    "navigate down by method/property/field
    autocmd FileType cs nnoremap <C-J> :OmniSharpNavigateDown<cr>

augroup END


" this setting controls how long to wait (in ms) before fetching type / symbol information.
set updatetime=500
" Remove 'Press Enter to continue' message when type information is longer than one line.
set cmdheight=2

" Contextual code actions (requires CtrlP or unite.vim)
nnoremap <leader><space> :OmniSharpGetCodeActions<cr>
" Run code actions with text selected in visual mode to extract method
vnoremap <leader><space> :call OmniSharp#GetCodeActions('visual')<cr>

" rename with dialog
nnoremap <leader>nm :OmniSharpRename<cr>
nnoremap <F2> :OmniSharpRename<cr>
" rename without dialog - with cursor on the symbol to rename... ':Rename newname'
command! -nargs=1 Rename :call OmniSharp#RenameTo("<args>")

" Force OmniSharp to reload the solution. Useful when switching branches etc.
nnoremap <leader>rl :OmniSharpReloadSolution<cr>
nnoremap <leader>cf :OmniSharpCodeFormat<cr>
" Load the current .cs file to the nearest project
nnoremap <leader>tp :OmniSharpAddToProject<cr>

" Start the omnisharp server for the current solution
nnoremap <leader>ss :OmniSharpStartServer<cr>
nnoremap <leader>sp :OmniSharpStopServer<cr>

" Add syntax highlighting for types and interfaces
nnoremap <leader>th :OmniSharpHighlightTypes<cr>
"Don't ask to save when changing buffers (i.e. when jumping to a type definition)
set hidden

" Enable snippet completion, requires completeopt-=preview
let g:OmniSharp_want_snippet=1

set ts=4
"Note: This option must set it in .vimrc(_vimrc).  NOT IN .gvimrc(_gvimrc)!
" Disable AutoComplPop.
let g:acp_enableAtStartup = 0
" Enable omni completion.
autocmd FileType css setlocal omnifunc=csscomplete#CompleteCSS
autocmd FileType html,markdown setlocal omnifunc=htmlcomplete#CompleteTags
autocmd FileType javascript setlocal omnifunc=javascriptcomplete#CompleteJS
autocmd FileType python setlocal omnifunc=pythoncomplete#Complete
autocmd FileType xml setlocal omnifunc=xmlcomplete#CompleteTags
autocmd FileType cs setlocal omnifunc=OmniSharp#Complete

" Enable heavy omni completion.

"let g:neocomplete#sources#omni#input_patterns.php = '[^. \t]->\h\w*\|\h\w*::'
"let g:neocomplete#sources#omni#input_patterns.c = '[^.[:digit:] *\t]\%(\.\|->\)'
"let g:neocomplete#sources#omni#input_patterns.cpp = '[^.[:digit:] *\t]\%(\.\|->\)\|\h\w*::'