[MacPorts] #53931: clang's ld doesn't recognise "-lto_library" flag on 10.6

[MacPorts]

#53931: clang's ld doesn't recognise "-lto_library" flag on 10.6
-------------------------------------------------+-------------------------
  Reporter:  mojca                               |      Owner:  jeremyhu
      Type:  defect                              |     Status:  new
  Priority:  Normal                              |  Milestone:
 Component:  ports                               |    Version:
Resolution:                                      |   Keywords:  snowleopard
      Port:  clang-3.9 clang-4.0 llvm-3.9        |
  llvm-4.0                                       |
-------------------------------------------------+-------------------------

Comment (by mojca):

 Thanks a lot for the analysis. These are the two relevant commits:
  * [changeset:393e9ab3d71d2e79d553e1373257f80b93d7c268/macports-ports
 393e9ab3]
     {{{
     ld64: Default to +ld64_127 on Snow Leopard
     }}}
  * [changeset:87e7b2fc0c4ba850dcd82b4cc3ddce0db939f17a/macports-ports
 87e7b2fc]
     {{{
     ld64-136: Mark port obsolete.

     Users should be able to use ld64-127, ld64-236, or ld64-latest
 instead.
     }}}

 I initially tried
 {{{
 sudo port -v install -ld64_127
 }}}
 which failed due to defunct clang 3.9. As expected and consistent with the
 fact that we don't have the package for `ld64-latest` for 10.6 from the
 buildbot. Note that `ld64-latest` needs `libc++`.

 Then I installed
 {{{
 sudo port install ld64 +ld64_236 -ld64_127
 }}}
 and after that `clang-3.9` was working again and I was able to install
 `ld64-latest` as well.

 Jeremy definitely changed the default variant because he wanted to retire
 the port `ld64-136`. Why he decided to go to `ld64-127` is something I
 don't know. Does `ld64-236` build on 10.6 out of the box without having
 `ld64-127` installed first? If so, we should definitely make `ld64-236`
 the default for 10.6. If not, we need some additional trickery, but we
 really need to fix this.

--
Ticket URL: <https://trac.macports.org/ticket/53931#comment:11>
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