[GHC] #15962: Type family & typeclass interaction suppresses errors

[GHC]

#15962: Type family & typeclass interaction suppresses errors
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        Reporter:  madgen            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  ⊥
       Component:  Compiler (Type    |              Version:  8.4.3
  checker)                           |             Keywords:  TypedHoles,
      Resolution:                    |  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by RyanGlScott):

 * keywords:  type family, typeclass, error message => TypedHoles, newcomer


Comment:

 Interesting program. It's conceivable that this was fixed by Tritlo's
 recent work on typed holes (possibly commit
 39de4e3d33dd9879398062620ad00b1e3b8481ce, although I haven't confirmed
 this). It //is// fixed now though, thankfully.

 In any case, I can't recall having a test case quite like this one (the
 test case from #15321, which the aforementioned commit fixed, requires
 Template Haskell), so it might be nice to add this as a test case as well.
 Any volunteers?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15962#comment:1>
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