[GHC] #15646: ghci takes super long time to find the type of large fractional number

[GHC]

#15646: ghci takes super long time to find the type of large fractional number
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        Reporter:  Johannkokos       |                Owner:
                                     |  JulianLeviston
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  GHCi              |              Version:  8.4.3
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #5692             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by JulianLeviston):

 This is the error (`./boot && ./configure && make -j4`):

 {{{
 WARNING: file compiler/iface/LoadIface.hs, line 428 GHC.Real
 GHC error in desugarer lookup in GHC.Real:
   Can't find interface-file declaration for variable mkRational
     Probable cause: bug in .hi-boot file, or inconsistent .hi file
     Use -ddump-if-trace to get an idea of which file caused the error
 ghc-stage1: panic! (the 'impossible' happened)
   (GHC version 8.7.20181219 for x86_64-apple-darwin):
         initDs

 Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug

 make[1]: *** [libraries/base/dist-install/build/GHC/Real.o] Error 1
 make: *** [all] Error 2
 }}}

 I'll make an MR now...

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15646#comment:71>
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