[GHC] #16305: When should -Wmissed-specializations fire?

[GHC]

#16305: When should -Wmissed-specializations fire?
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        Reporter:  crockeea          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.7
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by crockeea):

 Looks like your assessment is accurate, Simon. Perhaps the only problem
 here is a documentation issue, because I don't think the docs for
 `-Wmissed-specs` make it clear when a warning is issued.

 I'm also interested in understanding the warning from my example. The
 function names appear to be core, and it's not clear to me that
 `Data.Map.Internal.$fShowMap_$cshowsPrec` even corresponds to a function
 in source code. If that's the case, then the warning isn't very useful,
 either.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16305#comment:7>
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