[MacPorts] #62112: mpv fails to build on MacBook Pro 2014 15" High Sierra

[MacPorts]

#62112: mpv fails to build on MacBook Pro 2014 15" High Sierra
------------------------+----------------------------
 Reporter:  KomiaPoika  |      Owner:  (none)
     Type:  defect      |     Status:  new
 Priority:  High        |  Milestone:  MacPorts 2.7.0
Component:  ports       |    Version:  2.6.4
 Keywords:              |       Port:  mpv
------------------------+----------------------------
 Hi,

 I'm trying to build mpv from sources using Macports on High Sierra,
 MacBook Pro mid-2014 15" Iris+Nvidia. I get this error:

 https://pastebin.com/DfUPmenF

 I have xcode 9.4.1, which is needed for other apps, and XQuartz installed
 on the same system. The error has something to do with Swift, but I have
 no clue how to fix it.

 I also can't "upgrade" out of High Sierra, because I need it for
 proprietary software that is no longer supported beyond High Sierra.

 mpv also fails to build on my 13" MBp also High Sierra, but there I still
 have a previous build that works, whereas here is a fresh install so I
 can't run a built mpv at all.

-- 
Ticket URL: <https://trac.macports.org/ticket/62112>
MacPorts <https://www.macports.org/>
Ports system for macOS