ca@ca-laptop:~/fgfs/fg/src$ make
Making all in Include
make[1]: Entering directory `/home/ca/fgfs/fg/src/Include'
make  all-am
make[2]: Entering directory `/home/ca/fgfs/fg/src/Include'
make[2]: Nothing to be done for `all-am'.
make[2]: Leaving directory `/home/ca/fgfs/fg/src/Include'
make[1]: Leaving directory `/home/ca/fgfs/fg/src/Include'
Making all in Aircraft
make[1]: Entering directory `/home/ca/fgfs/fg/src/Aircraft'
g++ -DHAVE_CONFIG_H -I. -I../../src/Include -I../.. -I../../src  -I/home/ca/fgfs/sg/include -I/usr/local/include  -g -O2 -I/home/ca/fgfs/sg -D_REENTRANT -MT aircraft.o -MD -MP -MF .deps/aircraft.Tpo -c -o aircraft.o aircraft.cxx
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx: In member function ‘void SGSharedPtr<T>::get(const T*) const [with T = FGViewer]’:
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx:51:   instantiated from ‘SGSharedPtr<T>::SGSharedPtr(T*) [with T = FGViewer]’
../../src/Main/viewmgr.hxx:102:   instantiated from here
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx:91: error: no matching function for call to ‘SGReferenced::get(const FGViewer*&)’
/home/ca/fgfs/sg/include/simgear/structure/SGReferenced.hxx:42: note: candidates are: static unsigned int SGReferenced::get(const SGReferenced*)
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx: In member function ‘void SGSharedPtr<T>::put() [with T = FGViewer]’:
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx:58:   instantiated from ‘SGSharedPtr<T>::~SGSharedPtr() [with T = FGViewer]’
../../src/Main/viewmgr.hxx:102:   instantiated from here
/home/ca/fgfs/sg/include/simgear/structure/SGSharedPtr.hxx:93: error: no matching function for call to ‘SGReferenced::put(FGViewer*&)’
/home/ca/fgfs/sg/include/simgear/structure/SGReferenced.hxx:44: note: candidates are: static unsigned int SGReferenced::put(const SGReferenced*)
make[1]: *** [aircraft.o] Error 1
make[1]: Leaving directory `/home/ca/fgfs/fg/src/Aircraft'
make: *** [all-recursive] Error 1