[GHC] #12639: Inconsistent treatment of FlexibleInstances and MPTCs with standard vs. flexible deriving

[GHC]

#12639: Inconsistent treatment of FlexibleInstances and MPTCs with standard vs.
flexible deriving
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        Reporter:  dfeuer            |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      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 RyanGlScott):

 I have some opinions on both of these suggestions, but I'll refrain from
 posting them here. Before that, if you really want to see these changes
 make it into GHC, you should propose them as a post to the
 [https://mail.haskell.org/mailman/listinfo/ghc-devs GHC devs mailing
 list]. In particular, your second proposed item would cause a //lot// of
 code in the wild to break, so we need to discuss it more thoroughly to
 ensure it's a breakage we want to endorse.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12639#comment:1>
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