Domenico Tiziani / gammalib

Export MACOSX_DEPLOYMENT_TARGET only if --enable-universalsdk option is selected.

The export of MACOSX_DEPLOYMENT_TARGET led to some problems when trying to compile GammaLib on Mac OS X using the MacPorts gcc 4.4 compiler. The problems were uncatched exceptions that occured in some of the unit tests. After some debugging I discovered (by chance) that commenting the export of MACOSX_DEPLOYMENT_TARGET solved the problem.

Going into the Apple documentation (http://developer.apple.com/library/mac/#technotes/tn2064/_index.html) it appears that weak linking could be the root cause of the problems. With the current configuration on the Mac OS X 10.6 system on which the tests were done, MACOSX_DEPLOYMENT_TARGET=10.4. Following Apple's documentation, weak linking is implement from Mac OS X 10.2 on. Not specifying MACOSX_DEPLOYMENT_TARGET will automatically set the version to 10.1, hence no weak linking will be used.

Although I'm not 100% sure that weak linking indeed was the issue, removing the export of MACOSX_DEPLOYMENT_TARGET also removed the problems. I thus moved the export of MACOSX_DEPLOYMENT_TARGET into the --enable-universalsdk block, i.e. the export will only be done of the --enable-universalsdk option is selected. It remains to be seen whether this is the wanted behaviour.