[GHC] #8935: Obscure linker bug leads to crash in GHCi

[GHC]

#8935: Obscure linker bug leads to crash in GHCi
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        Reporter:  simonmar          |            Owner:  simonmar
            Type:  bug               |           Status:  infoneeded
        Priority:  high              |        Milestone:  7.8.3
       Component:  Runtime System    |          Version:  7.8.1-rc2
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  GHCi crash        |       Difficulty:  Rocket Science
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by simonmar):

 My apologies for making a buggy test program :-)  Thanks for eliminating
 the strangeness there.  So it seems that `dlsym` always returns a bogus
 result for `environ`.

 Your proposed fix only works if we load libraries with `RTLD_LOCAL` rather
 than `RTLD_GLOBAL`, I think.  That is probably fine, but it needs testing.
 This commit that introduced `internal_dlsym` explains the rationale:
 be497c202b790999c3fd0ddc4a4176b8cf6acf7e

 I'm fine with refactoring away the `hdl` argument.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8935#comment:29>
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