Mac OS X 64-bit, libstdc++ vs. libc++

Stephan Bergmann sbergman at
Thu Sep 11 03:16:22 PDT 2014

On 01/17/2014 10:02 AM, Stephan Bergmann wrote:
> The first appearance of LO for a new platform, like happens with 64-bit
> builds of LO 4.2 for Mac OS X now, is always a good time to revisit any
> decisions that may bite us later for backwards-compatibility.
> In the case of Mac OS X 64-bit, the natural thing to revisit is whether
> to use libstdc++ or libc++.  libstdc++ is the tried-and-tested GCC 4.2
> thing that we've been using ever since, but it is a dead end (due to
> Apple not upgrading past GCC 4.2 for license reasons) that will likely
> block future progress of using C++11 in LO (and I'd not be surprised if
> Apple drops it from a future OS X version).  On the other hand, libc++
> is clearly the way ahead on OS X, but somewhat less well tested with LO
> for now (only some individual developer builds having been configured to
> use it in the past).
> Now, the good news appears to be that "Libc++ is specifically designed
> so that you can use it in the same process as libstdc++."
> [<>]
>   That means that it hopefully works to stick with libstdc++ for LO 4.2
> (and avoid any trouble switching this late in the release schedule),
> switch to libc++ for LO 4.3 say, and expect any native extensions using
> either of the two libraries to work with both flavors of LO.  (And,
> given the assumption that Apple will eventually discontinue the support
> of libstdc++, recommend that native extensions---which there are none
> yet for Mac OS X 64-bit---use libc++.)

"Default to MAC_OS_X_VERSION_MIN_REQUIRED=1080 for Mac OS X SDK >= 10.8" 
on master towards LO 4.4, a build on Mac OS X against SDK >= 10.8 and 
with no explicit --with-macosx-version-min-required will now use libc++ 
instead of libstdc++, and I expect TDF Mac OS X builds towards LO 4.4 to 
in fact use libc++.


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