[GHC] #10614: Show constraints in ``Found hole...''

[GHC]

#10614: Show constraints in ``Found hole...''
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        Reporter:  bjmprice          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 This would not be hard.

 * Error messages generation is highly localised, in `TcErrors`

 * All the info about in-scope constraints is right there in the constraint
 tree, and is accessible in just the same way that we extract the "relevant
 bindings".  More easily, actually!

 The only hard bit is deciding exactly what to print, and with what flags
 to control it.

 I'm happy to offer guidance.

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10614#comment:5>
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