[CMake] Build doesn't work with Mac OS X Lion...

[Dick Munroe]

I've got a build that works just fine with Leopard.

For reasons I won't get into, I had to upgrade one of my systems to Lion 
and now (I've installed XCode 4.2) the build won't work.  I get the 
following error:

[  0%] Reaping winning child 0x10260c510 PID 1009
Live child 0x10260c510 
(libxp/CMakeFiles/xp.dir/Users/munroe/Documents/My_SVN/ESPlanner_Computation_Engine.U2011-11-01/Common/xmllib/print/libxp.cpp.o) 
PID 1010
Building CXX object 
libxp/CMakeFiles/xp.dir/Users/munroe/Documents/My_SVN/ESPlanner_Computation_Engine.U2011-11-01/Common/xmllib/print/libxp.cpp.o
Reaping winning child 0x10260c510 PID 1010
Live child 0x10260c510 
(libxp/CMakeFiles/xp.dir/Users/munroe/Documents/My_SVN/ESPlanner_Computation_Engine.U2011-11-01/Common/xmllib/print/libxp.cpp.o) 
PID 1011
llvm-g++-4.2: Invalid arch name : -O2
Reaping losing child 0x10260c510 PID 1011
make[2]: *** 
[libxp/CMakeFiles/xp.dir/Users/munroe/Documents/My_SVN/ESPlanner_Computation_Engine.U2011-11-01/Common/xmllib/print/libxp.cpp.o] 
Error 1
Removing child 0x10260c510 PID 1011 from chain.
Reaping losing child 0x10c20c290 PID 1008
make[1]: *** [libxp/CMakeFiles/xp.dir/all] Error 2
Removing child 0x10c20c290 PID 1008 from chain.
Reaping losing child 0x10940e730 PID 996

If I dig around, I find the CXX flags to be:

-arch  -O2 -fPIC

and for some reason the Lion g++ compiler is choking thinking that there 
should be and arch value.  Which if I dig around in the Leopard build I 
find:

-Dxp_EXPORTS  -arch i386 -O2 -g -fPIC

Which brings up the questions, (1) with the same CMakeLists.txt file, 
why am I getting different values and (2) how do I get the arch to be 
i386 on the Lion build.

Best,

Dick Munroe