MacPorts missing links

[David Epstein]

> On 11 Sep 2016, at 23:22, Ryan Schmidt <ryandesign at macports.org> wrote:
> 
> On my system I see the contents of that directory are provided by the following ports:
> 
> $ port provides /opt/local/etc/select/python3/*
> /opt/local/etc/select/python3/base is provided by: python3_select
> /opt/local/etc/select/python3/none is provided by: python3_select
> /opt/local/etc/select/python3/python33 is provided by: python33
> /opt/local/etc/select/python3/python34 is provided by: python34
> /opt/local/etc/select/python3/python35 is provided by: python35
> 
> What do you get if you run that "port provides" command?

I get
% port provides /opt/local/etc/select/python3/*
/opt/local/etc/select/python3/current is not provided by a MacPorts port.]

>> A final point, that I hope is not out-of-place. On my system
>>> port select —list llvm
>> 
>> responds with
>>> Available versions for llvm:
>>> 	mp-llvm-3.5
>>> 	none (active)
>> and you have told me that “mp-llvm-3.5” is not the name of a port.
> 
> That's correct. The name of the port is llvm-3.5. The name of its llvm select group entry is mp-llvm-3.5.
> 
>> I do not understand the issues involved and their ramifications, so I may be saying something stupid, but it seems to me, as a naive user, that this reveals a rather bad design fault in “port select”. An "available version" should either be “none” or the true name of an installed port. I realize that resources  to fix things are scarce, but could the ability to choose a random name at least be acknowledged as bad practice, and could a ticket be provided for work to be done so that this behaviour becomes impossible?
> 
> I think we don't consider this to be a design fault, but a feature. In other words, it was not a mistake that the select group entry can differ from a port; it was a deliberate decision to allow that. As has been pointed out, we want to be able to select things that are part of macOS and are not provided by a port.
Yes, Brandon Allbery explained this in an email prior to this one of yours. I hadn’t at all realized the existence of this feature, which is clearly a good idea.
> I agree that some of the select group entry names we've chosen are not optimal in the way in which they differ from the name of the port they provide. It might be a pain to fix that at this late date.