[GHC] #12200: ghc-pkg check complains about missing libCffi on dynamic-only install

[GHC]

#12200: ghc-pkg check complains about missing libCffi on dynamic-only install
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        Reporter:  dudebout          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  ghc-pkg           |              Version:  7.10.2
      Resolution:                    |             Keywords:  libCffi
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by thomie):

 Commit b30015e78db99d79cdb48c6c810e3fd49573c5cd is relevant:
 {{{
 Author: Ian Lynagh <ian at well-typed.com>
 Date:   Sat Mar 23 23:55:56 2013 +0000

     Change how we handle libffi

     I think overall the new approach is simpler. Rather than unpacking
     the libffi.a and putting the .o files into our libHSrts.a, we just
     use the libffi.a.

     This change also means that when compiling programs for the dyn
     way, they get explicitly linked against libffi.so (rather than
     relying on librts.so being linked against it). This might
     fix a problem on FreeBSD, where programs cannot find libffi.so.
 }}}

 In `compiler/main/Packages.hs`:
 {{{
            -- For non-Haskell libraries, we use the name "Cfoo". The .a
            -- file is libCfoo.a, and the .so is libfoo.so. That way the
            -- linker knows what we mean for the vanilla (-lCfoo) and dyn
            -- (-lfoo) ways. We therefore need to strip the 'C' off here.
 }}}

 I don't know why in `rts/package.conf.in`, `FFI_LIB` is listed in `hs-
 libraries`. It isn't a Haskell library, but because of its listing there,
 this code in `utils/ghc-pkg/Main.hs` is triggered:

 {{{
 checkHSLib :: Verbosity -> [String] -> String -> Validate ()
 checkHSLib _verbosity dirs lib = do
   let filenames = ["lib" ++ lib ++ ".a",
                    "lib" ++ lib ++ ".p_a",
                    "lib" ++ lib ++ "-ghc" ++ Version.version ++ ".so",
                    "lib" ++ lib ++ "-ghc" ++ Version.version ++ ".dylib",
                             lib ++ "-ghc" ++ Version.version ++ ".dll"]
   b <- liftIO $ doesFileExistOnPath filenames dirs
   when (not b) $
     verror ForceFiles ("cannot find any of " ++ show filenames ++
                        " on library path")

 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12200#comment:1>
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