[GHC] #8781: check if GNU nm is really needed and if so let configure detect gnm

[GHC]

#8781: check if GNU nm is really needed and if so let configure detect gnm
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        Reporter:  maeder               |            Owner:  kgardas
            Type:  feature request      |           Status:  patch
        Priority:  normal               |        Milestone:
       Component:  Build System         |          Version:  7.8.1-rc1
      Resolution:                       |         Keywords:
Operating System:  Solaris              |     Architecture:  x86
 Type of failure:  Building GHC failed  |       Difficulty:  Unknown
       Test Case:                       |       Blocked By:
        Blocking:                       |  Related Tickets:
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Comment (by jberthold):

 Maybe repetition is not good, but let me suggest to clarify which part is
 responsible for which variant of nm output. Also, one could use the Maybe
 monad instead of nested case expressions.
 how about this one:
 {{{
 parseNmLine xs0 = case words xs0 of
     -- "_derivedConstantMAX_Vanilla_REG C b 0" Mac OS X
     -- "derivedConstantMAX_Vanilla_REG C 0000000b 0000000b" GNU
     -- "_derivedConstantMAX_Vanilla_REG C 000000b" MinGW
                     x0 : "C" : x2 : r       -> mkMapping x0 x2
     -- "derivedConstantMAX_Vanilla_REG D        1        b" Solaris
                     x0 :  _  : x2 : x3 : [] -> mkMapping x0 x3
                     other -> Nothing

 mkMapping x0 x2 = do name <- stripPrefix $ dropWhile (== '_') x0
                      size <- case readHex x2 of [(n,"")] -> return n
                                                 _        -> fail "not hex"
                      return (name, size)
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8781#comment:30>
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