Is there any eclipse plugin that can generate UML/Class Diagram from C++ source code?
I don't know of any Eclipse Plugins that generates UML class diagram from C++ code. However, BOUML is now commercial, but version 4 was free. You can still find this version in several repos of Linux distributions, it has the best reverse engineering features I've ever seen in a free application. It runs on Windows too, you can still find the installer of BOUML 4 for Windows on the Internet.