[GHC] #14273: Typed holes' "valid substitutions" suggestions are oblivious to type class constraints

[GHC]

#14273: Typed holes' "valid substitutions" suggestions are oblivious to type class
constraints
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9091             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dfeuer):

 Replying to [comment:5 Tritlo]:

 > About the missing constraint: if you add the -fshow-hole-constraints
 flag, you'll get a "Constraints include" part in the hole's type error
 message. Maybe it should be on by default? It seems that this blog post
 highlights that users would like to know that about the hole.

 Yes please! I didn't even know this option existed. If it's not on by
 default (which I imagine it should be), GHC should at least suggest it
 every time it encounters a typed hole that has constraints.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14273#comment:6>
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