[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:  normal    |        Milestone:
       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):

 I looked into this a bit (with `cabal install --ghc-option=-v3 -v -v -v`)
 and it looks like

 * there are (at least) two modules in `lens` which use Template Haskell,
 `Control.Lens.At` and `System.IO.Error.Lens`

 * when building the first one `Control.Lens.At`, ghc correctly links the
 modules it needs to run the TH into a little shared library

 * when building the second one `System.IO.Error.Lens`, ghc doesn't include
 any modules (I only did a couple spot checks here, but) that were built
 before `Control.Lens.At` when building the shared library for TH. In
 particular, it includes `Control.Lens.TH` but not
 `Control.Lens.Internal.TH` which the former depends on.

 I didn't attempt to investigate in the source code why this is happening.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8696#comment:2>
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