[GHC] #9681: Printing of "\n" in error messages is broken

11 Oct 2014


      #9681: Printing of "\n" in error messages is broken
-------------------------------------+-------------------------------------
       Reporter:  oerjan             |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.8.3
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:  1+"\n"
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 The code excerpts in error messages from GHC 7.8.3 are misformatted when
 the original code contains the string "\n" - the \n escape is simply lost.
 Example with GHCi:

 {{{
 Prelude> 1+"\n"

 <interactive>:2:2:
     No instance for (Num [Char]) arising from a use of `+'
     In the expression: 1 + ""
     In an equation for `it': it = 1 + ""
 }}}

 The printing of the string "\n " is also strangely formatted, although
 technically equivalent:

 {{{
 Prelude> 1+"\n "

 <interactive>:3:2:
     No instance for (Num [Char]) arising from a use of `+'
     In the expression:
       1
       + "\n\
         \ "
     In an equation for `it':
         it
           = 1
             + "\n\
               \ "
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9681
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