Keeping track of automatically installed dependency-only ports

[Stephen Hurd]

>> If thingYYY detects SDL and uses it at configure stage, it should be
>> recorded in the dependency list.
>>     
>
> Agreed, but this situation is not easy to detect with the automated
> ports checks that are in place.
>   

Impossible even since we're not using automated tools.

> Yes - but since it requires the maintainer to manually determine what
> features are automatically detected and enabled, it is something that
> is error-prone - the maintainer could easily accidently overlook it.
>   

A maintainer needs to do this anyways.

>> exists or not, nothing would prevent the user from deinstalling SDL
>> and break thingYYY otherwise.
>>     
>
> Unfortunately, I can't think of any way to automatically detect this
> situation.  This means that we are basically limited to waiting for
> people to trip over instances of the problem and report it.
>   

Of course, simply not automatically deinstalling SDL would help out 
quite a bit.  If I decide to remove SDL, all the results of that are my 
fault.  If removing portXXX also removes SDL, I can blame the ports 
system for removing stuff out from under me.