with the symbol database it should be possible to test a file for missing includes. you could check all class names and look for the include of the corresponding h-file. there may be problems with 'using namespace' and things like that but a first version should not be too har to implement. would be a great feature to avoid missing includes that were included by an already existing include in the origiginal version of the file.
There may be many special cases like preprocessor statements, macros, scope problems and other stuff. But what about a first version testing a) includes that are not needed b) missing includes c) information about lines of code that not so easy to decide
one could work them through and would have a good feeling. You could insert a rule to just apply the feature to code that compiles error and warning free. by this way, it would be easy to get rid of indirect includes.