[GHC] #10011: The Data instance for Ratio violates internal invariants.

[GHC]

#10011: The Data instance for Ratio violates internal invariants.
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        Reporter:  ekmett            |                   Owner:  ekmett
            Type:  bug               |                  Status:  closed
        Priority:  normal            |               Milestone:  7.10.1
       Component:  Core Libraries    |                 Version:  7.10.1-rc1
      Resolution:  fixed             |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D625
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"22c4d60b0665a15535c0ec9fe0b8e65d2c948e7d/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="22c4d60b0665a15535c0ec9fe0b8e65d2c948e7d"
 Revert "Restore invariant in `Data (Ratio a)` instance"

 This reverts commit 79b0d0e633af8302d2dd907663a4a231cd889b67
 due to

   Compile failed (status 256) errors were:
   [1 of 2] Compiling A                ( A.hs, A.o )
   [2 of 2] Compiling Main             ( T4491.hs, T4491.o )
   T4491.hs:19:11:
     Illegal data constructor name: ‘%’
     When splicing a TH expression: (GHC.Real.%) 11 2
     In the splice: $(dataToExpQ (const Nothing) (5.5 :: Rational))
   *** unexpected failure for T4491(normal)

 Therefore re-opening #10011
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10011#comment:7>
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