[GHC] #15114: ghc 8.4.1 optimizes True to False

[GHC]

#15114: ghc 8.4.1 optimizes True to False
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        Reporter:  elaforge          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.1
      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):

 I think the bug also does not manifest in GHC 8.2.2.

 It's probably already-fixed, but at least it's an excellent regression
 test. And I'd like to be sure that it really IS fixed, rather than merely
 concealed, in 8.4.2.

 Does anyone feel able to bisect to the commit that fixes it?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15114#comment:4>
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