[GHC] #16048: Show Instance for IOException discards error code

[GHC]

#16048: Show Instance for IOException discards error code
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        Reporter:  andrewthad        |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by makos):

 I can provide example outputs based on compiled ghc (old/new):

 Original behaviour:
 {{{
 System.Directory.renameFile "a.a" ""
 *** Exception: a.a: renameFile:renamePath:rename: does not exist (No such
 file or directory)
 }}}


 Updated behaviour:
 {{{
 System.Directory.renameFile "a.a" ""
 *** Exception: a.a: renameFile:renamePath:rename: does not exist (2) (No
 such file or directory)

 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16048#comment:4>
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