Having the simplest project ever I met issue that QCoreApplication is not properly parsed, as I suppose.
First manifestation is "bad" colorizing. Class name have the same color as preprocesor directive.
Second manifestation is that when I move mouse cursor over this class name then nothing happen.
Because QCoreApplication is located in QtCore I also added into Includes/Imports (project configuration)  path to QtCore (for me this is /usr/include/Qt/QtCore where is bunch of headers) and reparsed the project.

Below please find the only one function from this project. For your convenience I also attached archive containing this project.

#include <QCoreApplication>

int main(int argc, char** argv)
{
	QCoreApplication app(argc, argv);

	return app.exec();
}

Please note this is come from KDevelop plugin "New Project Wizard".
Generated by option: "Project -> New from template", where:
"Category" is "Qt"
"Project Type" is "Terminal"


Reproducible: Always

Steps to Reproduce:
1. Clear ~/.cache/kdevduchain cache
2. Run KDevelop
3. Open attached project
4. Open file main.cpp
5. Move mouse cursor over QCoreApplication

Actual Results:  
nothing happen

Expected Results:  
should be shown tool tip referring to QCoreApplication

Kate, KTextEditor, KDevelop, KDevplatform cloned at 04.11.2015

I'm not sure, but maybe the reason is the same like in Bug 354846 - QCollator class name is not colorized in global function