Add option to link with libc++ on older OSX versions.

Versions of OSX lower than 10.9 link libstdc++ by default.
Also libstdc++ is linked when the osx minimum deployment target is
lower than 10.9.

The new option allows explicitly linking libc++ in the cases mentioned
above. It is not enabled by default, because most libraries and
executables on versions lower than 10.9 are compiled with libstdc++,
and mixing standard library versions can lead to crashes.

Change-Id: I7397d2bbce2cfceaeb848f25e0bbf1a24ac9bde8
Reviewed-by: Christian Tismer <tismer@stackless.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index b7cd3fb9c..236d9f1e8 100644
--- a/setup.py
+++ b/setup.py
@@ -160,6 +160,7 @@ OPTION_JOBS = option_value('jobs')                # number of parallel build job
 OPTION_JOM = has_option('jom')                    # use jom instead of nmake with msvc
 OPTION_BUILDTESTS = has_option("build-tests")
 OPTION_OSXARCH = option_value("osx-arch")
+OPTION_OSX_USE_LIBCPP = has_option("osx-use-libc++")
 OPTION_XVFB = has_option("use-xvfb")
 
 if OPTION_QT_VERSION is None:
@@ -634,6 +635,15 @@ class pyside_build(_build):
                 # also tell cmake which architecture to use
                 cmake_cmd.append("-DCMAKE_OSX_ARCHITECTURES:STRING={}".format(OPTION_OSXARCH))
 
+            if OPTION_OSX_USE_LIBCPP:
+                # Explicitly link the libc++ standard library (useful for osx deployment targets
+                # lower than 10.9). This is not on by default, because most libraries and
+                # executables on OSX <= 10.8 are linked to libstdc++, and mixing standard libraries
+                # can lead to crashes.
+                # On OSX >= 10.9 with a similar minimum deployment target, libc++ is linked in
+                # implicitly, thus the option is a no-op in those cases.
+                cmake_cmd.append("-DOSX_USE_LIBCPP=ON")
+
         log.info("Configuring module %s (%s)..." % (extension,  module_src_dir))
         if run_process(cmake_cmd) != 0:
             raise DistutilsSetupError("Error configuring " + extension)