I just upgraded from Qt Creator 3.6.0 to 4.1.0 and now autocomplete no longer works when typing arguments for a function call. This was not a problem with previous versions of Qt Creator.

For example:

double angle1(1.0), angle2(2.0), result;

angle1 = angle1 + angle2; //autocomplete works here for angle1 and angle2
result = cos(angle1); //autocomplete works for "result" but not "angle1"

Edit: Still an issue in the latest release (4.2.1).