[GHC] #9174: Haddock fails with "Module defined in multiple files"

[GHC]

#9174: Haddock fails with "Module defined in multiple files"
---------------------------------+----------------------------------
        Reporter:  mietek        |            Owner:
            Type:  bug           |           Status:  new
        Priority:  normal        |        Milestone:
       Component:  Compiler      |          Version:  7.8.2
      Resolution:                |         Keywords:
Operating System:  MacOS X       |     Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown  |       Difficulty:  Unknown
       Test Case:                |       Blocked By:
        Blocking:                |  Related Tickets:
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Description changed by mietek:

Old description:

> Haddock fails to cooperate with OS X clang CPP:
> {{{
> <no location info>:
>     module ‘pkgid-pkgversion:Main’ is defined in multiple files:
> dist/build/tmp-#####/Stuff
> }}}
>
> A workaround is to pass `--ghc-options=-optP-P` to `cabal haddock`.
>
> This prevents `cabal-install` from being boostrapped, unless `--no-doc`
> is specified.
>
> The original Haddock ticket and the corresponding Cabal issue were both
> closed as invalid, but there appears to be no GHC ticket to track the
> underlying cause.
> http://trac.haskell.org/haddock/ticket/284
> https://github.com/haskell/cabal/issues/1740

New description:

 Haddock fails to cooperate with OS X clang CPP:
 {{{
 <no location info>:
     module ‘pkgid-pkgversion:Main’ is defined in multiple files:
 dist/build/tmp-#####/Stuff
 }}}

 A workaround is to pass `--ghc-options=-optP-P` to `cabal haddock`.

 This prevents `cabal-install` from bootstrapping, unless `--no-doc` is
 specified.

 The original Haddock ticket and the corresponding Cabal issue were both
 closed as invalid, but there appears to be no GHC ticket to track the
 underlying cause.
 http://trac.haskell.org/haddock/ticket/284
 https://github.com/haskell/cabal/issues/1740

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9174#comment:1>
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