Thomas,
I will change the compiler.
GREAT!! Thank you! I've got a 10.9 laptop where the problem occurs but have several other computers that I can't move to 10.9 until the compiler is ready so I hope this is an easy change. So I could do tests if you like.
As an intermediate solution, the following works for me on 10.9
adriaan% gp hello.pas -Wl,-macosx_version_min,10.5 adriaan% ./hello Hello, world.
adriaan% gp hello.pas -Wl,-macosx_version_min,10.6 adriaan% ./hello Hello, world.
adriaan% gp hello.pas -Wl,-macosx_version_min,10.7,-no_pie adriaan% ./hello Hello, world.
This doesn't seem to require any of the SDKs, assuming that you previously installed libSystemStubs.
Regards,
Adriaan van Os