[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 nomeata):

 I moved the `exprSize` idea to #13374.

 >  I have no explanation for that!!

 Might be a misunderstanding in how I use the GHC API. (It seems that the
 instance of `map` on the RHS of a rule has no rules in its `IdInfo`, and
 so it does not fire. I’ll ask on the mailing list about that once I get to
 it.)

 >  Want to try adding that? [mapFB rule]

 I’m trying that: Phab:D3275

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13353#comment:6>
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