[GHC] #10298: Infinite loop when shared libraries are unavailable

[GHC]

#10298: Infinite loop when shared libraries are unavailable
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        Reporter:  snoyberg          |                   Owner:  simonmar
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Runtime System    |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86_64
 Type of failure:  Runtime crash     |  (amd64)
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by hsyl20):

 I have an additional fix to propose for this bug: handle Unicode to ASCII
 conversions in GHC without Iconv:

 {{{
 diff --git a/libraries/base/GHC/IO/Encoding.hs
 b/libraries/base/GHC/IO/Encoding.hs
 index 31683b4..c67f317 100644
 --- a/libraries/base/GHC/IO/Encoding.hs
 +++ b/libraries/base/GHC/IO/Encoding.hs
 @@ -243,6 +243,7 @@ mkTextEncoding' cfm enc = case [toUpper c | c <- enc,
 c /= '-'] of
      "UTF32"   -> return $ UTF32.mkUTF32 cfm
      "UTF32LE" -> return $ UTF32.mkUTF32le cfm
      "UTF32BE" -> return $ UTF32.mkUTF32be cfm
 +    "ANSI_X3.41968" -> return char8 -- match "ANSI_X3.4-1968" (ASCII)
  #if defined(mingw32_HOST_OS)
      'C':'P':n | [(cp,"")] <- reads n -> return $
 CodePage.mkCodePageEncoding cfm cp
      _ -> unknownEncodingErr (enc ++ codingFailureModeSuffix cfm)
 }}}

 It seems that static binaries fall back to ASCII even if the current
 locale is UTF-8. ASCII is identified with the string "ANSI_X3.4-1968" on
 my system (Linux 4.0, glibc 2.21). Maybe we should match other possible
 aliases?

 I tested this patch with a single static binary in a initramfs and it
 works fine now. It should fix #7695 too (single static binary in a
 chrooted environment).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10298#comment:9>
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