Issues with completion

[ghost]

Maybe there's someone else that's using vim-lsp here. I've installed the the asyncomplete-lsp, asyncomplete and vim-lsp plugins and 'ccls' is set with

autocmd User lsp_setup call lsp#register_server({
    \ 'name': 'ccls',
    \ 'cmd': {server_info->['ccls']},
    \ 'whitelist': ['c', 'cpp', 'objc', 'objcpp', 'cc'],
    \ 'filter': {'name': 'prefix'},
    \ 'config': { 'snippets': 0 },
    \ })

and vim-lsp with

let g:lsp_diagnostics_enabled = 0
let g:lsp_preview_float = 1
let g:lsp_preview_autoclose = 1
let g:lsp_completion_documentation_enabled = 1

function! s:on_lsp_buffer_enabled() abort
    setlocal omnifunc=lsp#complete
    setlocal signcolumn=yes
    if exists('+tagfunc') | setlocal tagfunc=lsp#tagfunc | endif
    nmap <buffer> gd <plug>(lsp-definition)
    nmap <buffer> gs <plug>(lsp-document-symbol-search)
    nmap <buffer> gS <plug>(lsp-workspace-symbol-search)
    nmap <buffer> gr <plug>(lsp-references)
    nmap <buffer> gi <plug>(lsp-implementation)
    nmap <buffer> gt <plug>(lsp-type-definition)
    nmap <buffer> <leader>rn <plug>(lsp-rename)
    nmap <buffer> [g <Plug>(lsp-previous-diagnostic)
    nmap <buffer> ]g <Plug>(lsp-next-diagnostic)
    nmap <buffer> K <plug>(lsp-hover)
endfunction

when I'm typing for example 'printf', I see a list of functions. However, when I'm selecting a function I'm getting not only 'printf' but 'printf(const char *restricted __format, ...) -> int'. Same goes if i'm selecting a variable. I'm getting 'server_adress : struct sockaddr_in' instead of 'server_adress'. Is this how it's supposed to be and if not, does someone here maybe know how to fix it?