[GHC] #8696: linking fails with 'relocation R_X86_64_PC32 against undefined symbol'

[GHC]

#8696: linking fails with 'relocation R_X86_64_PC32 against undefined symbol'
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        Reporter:  Kata      |            Owner:
            Type:  bug       |           Status:  new
        Priority:  highest   |        Milestone:  7.8.1
       Component:  Compiler  |          Version:  7.8.1-rc1
      Resolution:            |         Keywords:
Operating System:  Linux     |     Architecture:  x86_64 (amd64)
 Type of failure:  Other     |       Difficulty:  Unknown
       Test Case:            |       Blocked By:
        Blocking:            |  Related Tickets:
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Comment (by rwbarton):

 The relevant code is in `compiler/ghci/Linker.lhs`, functions
 `linkDependencies`, `getLinkDeps`, `dynLinkObjs` and `dynLoadObjs`. When
 linking in a module GHC attempts to link ''all the object files that are
 not already loaded into GHC'' into a single shared library and then dlopen
 that library. That fails here because `T8696B.o` apparently contains a PC-
 relative relocation to `T8696A.o` and therefore cannot be dynamically
 linked to it.

 I noticed that both `getLinkDeps` and `dynLinkObjs` seem to be guilty of
 pruning modules/object files that have already been loaded into GHC from
 the list of dependencies to link together. But even if they did not prune
 any dependencies, would there then be problems with two copies of
 `T8696A.o` being loaded into GHC? So I'm not sure what the right fix is
 here.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8696#comment:7>
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