[GHC] #12485: -package-db flags now need to be sorted by dependency order

[GHC]

#12485: -package-db flags now need to be sorted by dependency order
-------------------------------------+-------------------------------------
        Reporter:  niteria           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Package system    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  phab:D2450
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by niteria):

 Thank you for your detailed response! I can't think of a better way of
 handling things, so I'm fine with just making it a bit more clear in the
 documentation. I didn't make the leap from understanding how shadowing is
 handled to how it impacts the expected order of `-package-db` flags.

 I shall make the test case not `expect_broken`, but expect the current
 behaviour. I believe it's useful to keep it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12485#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler