[Bug lto/49992] lto-bootstrap reveals duplicate symbols on x86_64-apple-darwin11

["iains at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49992

--- Comment #39 from Iain Sandoe <iains at gcc dot gnu.org> 2011-08-11 08:52:24 UTC ---
(In reply to comment #37)
> This issue is not fixed.

concur.

Mike; there are two problems.

a.  the link line for gcc/gengtype (recently introduced) includes both errors.o
and libcommon.a

  - this could cause a conflict on any system if, say, fatal_error (resolved
from diagnostics.o) and fatal (resolved from errors.o) were called.

  - comment 6. addresses this.

b. the "regression" in Darwin's ld that causes it to load the first member of
an archive that includes a used common symbol.  

 - this will always happen with LTO, which uses a common symbol "___gnu_lto_v1"
to flag that an object has been built LTO (see toplev.c).

- it can also happen subtly and randomly with other cases using common symbols.

* the vendor's response to a repost on this ld bug is "The preferred solution
is to not use -c with ranlib.  "

 ... unless you can produce a patch (or identify a plan for such a patch) that
would obviate the need for common symbols in the darwin port, it doesn't seem
that we have any realistic expectation of fixing this in any other way than
comment 32.