[GHC] #12790: GHC 8.0.1 uses copious amounts of RAM and time when trying to compile lambdabot-haskell-plugins

[GHC]

#12790: GHC 8.0.1 uses copious amounts of RAM and time when trying to compile
lambdabot-haskell-plugins
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        Reporter:  clint             |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      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 RyanGlScott):

 Simon, I've opened #12936 to figure out that `parsec` issue.

 Until then, you can work around it by checking out a local copy of
 `parsec-3.1.11` with `cabal get parsec-3.1.11`, edit
 `parsec-3.1.11/Text/Parsec/Token.hs`, and change the definition to
 `makeTokenParser = undefined`. I don't believe its definition is used in
 this example anyways.

 Moreover, after making that change, I can confirm that the example in
 https://ghc.haskell.org/trac/ghc/ticket/12790#comment:7 also exhibits the
 same slowdown in GHC HEAD (compiling it with `-O -prof`, of course).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12790#comment:9>
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