[GHC] #10477: Tab-completing in a directory with Unicode heiroglyph crashes ghci

[GHC]

#10477: Tab-completing in a directory with Unicode heiroglyph crashes ghci
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        Reporter:  acfoltzer   |                   Owner:
            Type:  bug         |                  Status:  new
        Priority:  normal      |               Milestone:
       Component:  GHCi        |                 Version:  7.10.1
      Resolution:              |                Keywords:
Operating System:  Windows     |            Architecture:  Unknown/Multiple
 Type of failure:  GHCi crash  |               Test Case:
      Blocked By:              |                Blocking:
 Related Tickets:              |  Differential Revisions:
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Comment (by AlexET):

 This specific problem comes from haskeline. It uses `map (toEnum .
 fromEnum)` to convert a `String` to a list of `Word16` before printing the
 string. This fails in this case of wider characters which need to be
 encoded with a surrogate pair. There is a six year old ticket here
 http://trac.haskell.org/haskeline/ticket/63.

 The bad news is that printing using the functions in the prelude has even
 worse unicode support on windows. It seems to print garbage (this includes
 for the unicode quotes in compiler error messages). If we are in the
 standard code page we just get errors (as expected).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10477#comment:1>
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