[GHC] #12479: build fail of commercialhaskell.com with stack build on mac os x sierra beta 4

[GHC]

#12479: build fail of commercialhaskell.com with stack build on mac os x sierra
beta 4
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        Reporter:  stephenb          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  MacOS X           |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #12198            |  Differential Rev(s):  Phab:D2532
       Wiki Page:                    |
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Comment (by bgamari):

 darchon said,
 > I'm not sure, but I think GHC also nubs the `RPATH`s (in the case of
 dynload system), this would have to be checked.

 For the record, I believe we compute the linker command line in
 `SysTools.linkDynLib`, which calls `collectLibraryPaths` to compute the
 set of needed `RPATH` directories. `collectLibraryPaths` indeed calls
 `nub`, but it does **not** `sort` before doing so, meaning that `nub`
 won't always remove all duplicates. This should be fixed.

 `Cabal` should also be checked for this issue.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12479#comment:40>
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