[GHC] #13353: foldr/nil rule not applied consistently

[GHC]

#13353: foldr/nil rule not applied consistently
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 >  I just had a project where it made a difference whether I add `{-#
 RULES "foldr/nil" forall k n . GHC.Base.foldr k n [] = n #-}` to my file
 or not, despite this rule already being present in the library.

 I have no explanation for that!!

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13353#comment:5>
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