Map ] as a go-to-source function, which call file-type-specific go-to functions.
" Call YCM GoTo or vim-go GoTo depending on file type.
function! GoToDef()
if &ft == 'go'
call go#def#Jump()
else
execute 'YcmCompleter GoTo'
endif
endfunction
nnoremap <leader>] :call GoToDef()<CR>