title: Make vim keyword completion menu show function parameters
body: <h1>Problem</h1>
  <p>I want to make the vim <strong>keyword</strong> completion menu show the parameters of the functions it proposes to me.
  I would like it to look something like this :</p>
  <p><a href="https://i.stack.imgur.com/dyNqx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dyNqx.png" alt="screenshot of vim omni completion using ctags" /></a></p>
  <p>This is omni-completion using ctags, it is great but it is slow, so i can't use it with a large tags file.</p>
  <h1>Issues</h1>
  <p>Here's what my current keyword completion using ctags looks like (<code>set complete=t</code>) :</p>
  <p><a href="https://i.stack.imgur.com/PWHYU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PWHYU.png" alt="screenshot of vim keyword completion using ctags" /></a></p>
  <h1>My research</h1>
  <p>I tried to look at vim's doc (<code>ins-completion, 'complete', 'completeopt', 'completefunc', 'omnifunc', 'ft-c-omni'</code>) but the only way to achieve my goal seems to write my own <code>'completefunc'</code> what i don't feel like to do.</p>
  <p>However i found that i can get a popup menu showing the informations i want, but with my current configuration (<code>set completeopt=menuone,noinsert,popup</code>) it shows up only in omni completion which, again, is too slow.</p>