PhpStorm code completion doesn't show core classes/extensions

Question

I'm having trouble with PHPStorm. I just started new project created a couple of my own classes, in one of them I created PDO object.

$this->cnn = new PDO("sqlite:db/base.db"); 

Now when I want to see what kind of methods this object has via crtl + whitespace, I get no suggestions. Then I tried to see the list of classes available to me with.

$newClass = new 

And when I pressed ctrl + whitespace it only showed me the classes I created.

So the question is, what do i need to do, to make PhpStorm see all the classes that are available (not just the ones i created).

P.S. when i ctrl + click on PDO (which is underlined) it says that class is undefined

P.P.S. in project settings i have selected php 5.4 language language and selected interpreter (php 5.4.7, using xampp)

Answer 1

I've solved the issue. File > Invalidate Caches did the trick!