[GHC] #15425: GHC does not warn when two conflicting packages with same name are given via a dependent package and -package-db

[GHC]

#15425: GHC does not warn when two conflicting packages with same name are given
via a dependent package and -package-db
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        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Build System      |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nh2):

 `ezyang__` from IRC:


 > ok, I think I agree with your diagnosis
 >
 > one of the problems with warning in the default package mode (without
 -hide-all-packages) is that, in most databases, there are lots of
 inconsistent versions of things, so it would be warning basically all the
 time
 >
 > so you'd have to implement this after you handled imports; THEN check
 that the transitive closures of packages make sense

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15425#comment:1>
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