Undefined reference to vtable. Trying to compile a Qt project

Warning: Do not do this if you already have a .pro file - you'll lose it!

In order to automatically ensure that all moc cpp files are generated, you can get qmake to automatically generate a .pro file for you instead of writing one yourself.

Run

qmake -project

in the project directory, and qmake will scan your directory for all C++ headers and source files to generate moc cpp files for.