[GHC] #15696: Derived Ord instance for enumerations with more than 8 elements seems to be incorrect

[GHC]

#15696: Derived Ord instance for enumerations with more than 8 elements seems to be
incorrect
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        Reporter:  mrkkrp            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.6.2
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D5196
       Wiki Page:                    |
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Comment (by osa1):

 I'm confused

 > That's what you get for monoidal's code in comment:18

 I didn't even look at comment:18. I tried your code in comment:13 and what
 happens there is exactly what I explained in my patch.

 > The evals are there, as comment:14 shows.

 comment:14 shows that evals are there if I don't inline `cmpT`, and that
 makes sense as I explained in comment:31. We can't assume that args are
 evaluated so we eval them.

 > And yet we get the wrong answer.

 I get the right answer when I get the STG in comment:14.

 Could you try to reproduce the error in comment:14 and give me more
 detailed instructions (showing the source and invoked GHC commands)?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15696#comment:33>
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