[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:
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Comment (by darchon):

 I currently don't have my OS X machine, so I can't make the patch right
 now. But the patch should be "straightforward": just make OS X (MACH-O)
 behave the same way as Linux (ELF). I guess this whole mess started in the
 first place because MACH-O only has absolute paths to dynamic libraries.

 Currently on OS X there's a single point of reference, an `@rpath`, that's
 pointing to a `lib/` directory, and expecting all libraries bundled with
 GHC to be there. This should be changed to multiple `@rpath`s. So the
 current situation looks like this:
 {{{
 -- Installed by GHC install
 @rpath/package1-package1version/package1.dylib
 @rpath/package2-package1version/package2.dylib
 @rpath/package3-package1version/package3.dylib
 -- Installed by Cabal
 /absolute_path_to_library/package4.dylib
 /absolute_path_to_library/package5.dylib
 }}}
 Where a executable gets an `@rpath` pointing to the same location as the
 value of `ghc --print-libdir`. With the exception of the GHC binary, which
 has an `@rpath` pointing to `@loader_path/..`.

 The new situation should be:
 {{{
 -- Installed by GHC install
 @rpath/package1.dylib
 @rpath/package2.dylib
 @rpath/package3.dylib
 -- Installed by Cabal
 @rpath/package4.dylib
 @rpath/package5.dylib
 }}}
 Where:
 * Libraries bundled with GHC should get, for all transitively depending
 libraries, an `@rpath` pointing to `@loader_path/../dependentpackage/`
 (similar to the situation on Linux, which uses
 `$ORIGIN/../dependentpackage/`)
 * The GHC executable should get, for all transitively depending libraries,
 an `@rpath` pointing to `@loader_path/../dependentpackage/` (again similar
 to Linux)
 * Libraries installed by Cabal should get, for all transitively depending
 library, an `@rpath` pointing to `/absolute_path_to_package` (similar to
 linux)
 * Executables should get, for all transitively depending libraries, an
 `@rpath` pointing to `/absolute_path_to_package` (similar to linux)

 This patch would involve adding a code-path for OS-X/MACH-O similar to
 lines 1757-1776 in `compiler/main/DriverPipeline.hs`, and of course
 changing `rules/relative-dynlib-references.mk`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8266#comment:30>
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