[GHC] #8266: Dynamic linking on Mac

[GHC]

#8266: Dynamic linking on Mac
--------------------------------------------+------------------------------
        Reporter:  kazu-yamamoto            |            Owner:
            Type:  bug                      |  thoughtpolice
        Priority:  highest                  |           Status:  closed
       Component:  Build System             |        Milestone:  7.8.1
      Resolution:  fixed                    |          Version:  7.7
Operating System:  MacOS X                  |         Keywords:
 Type of failure:  GHC doesn't work at all  |     Architecture:
       Test Case:                           |  Unknown/Multiple
        Blocking:                           |       Difficulty:  Unknown
                                            |       Blocked By:
                                            |  Related Tickets:
--------------------------------------------+------------------------------

Comment (by darchon):

 The latest patch makes Mach-O (currently just Darwin, not iOS) behave the
 same as ELF in terms of dynamic linking. That is, all dynamic library
 locations are now relative to `@rpath`, and GHC adds `LC_RPATH` commands
 for every directory containing the dependent libraries. This enables the
 use-case of using `cabal -w inplace/bin/ghc-stage2`.

 Cabal will however need an update as well, as libraries installed by Cabal
 will still use absolute paths:
 {{{
 -- Installed by GHC install
 @rpath/package1.dylib
 @rpath/package2.dylib
 @rpath/package3.dylib
 -- Installed by Cabal
 /absolute_path_to_library/package4.dylib
 /absolute_path_to_library/package5.dylib
 }}}

 By applying the following patch to Cabal:
 {{{
 diff --git a/Cabal/Distribution/Simple/GHC.hs
 b/Cabal/Distribution/Simple/GHC.hs
 index c7ea633..78cdcbb 100644
 --- a/Cabal/Distribution/Simple/GHC.hs
 +++ b/Cabal/Distribution/Simple/GHC.hs
 @@ -867,11 +867,6 @@ buildOrReplLib forRepl verbosity pkg_descr lbi lib
 clbi = do
                ghcOptDynLinkMode        = toFlag GhcDynamicOnly,
                ghcOptInputFiles         = dynamicObjectFiles,
                ghcOptOutputFile         = toFlag sharedLibFilePath,
 -              -- For dynamic libs, Mac OS/X needs to know the install
 location
 -              -- at build time.
 -              ghcOptDylibName          = if buildOS == OSX
 -                                          then toFlag
 sharedLibInstallPath
 -                                          else mempty,
                ghcOptPackageName        = toFlag pkgid,
                ghcOptNoAutoLinkPackages = toFlag True,
                ghcOptPackageDBs         = withPackageDB lbi,
 }}}

 The situation will change to:
 {{{
 -- Installed by GHC install
 @rpath/package1.dylib
 @rpath/package2.dylib
 @rpath/package3.dylib
 -- Installed by Cabal
 @rpath/package4.dylib
 @rpath/package5.dylib
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8266#comment:31>
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