Problem installing

[TheSkallywag]

I am trying to build saga-gis for Ubuntu 20 using these instructions:
https://sourceforge.net/p/saga-gis/wiki/Compiling%20SAGA%20on%20Linux/

I have wxWidgets 3.0.4

[ 11%] Building CXX object src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/res_commands.cpp.o
[ 11%] Building CXX object src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/res_controls.cpp.o
[ 11%] Building CXX object src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/res_dialogs.cpp.o
[ 11%] Building CXX object src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/res_images.cpp.o
[ 11%] Building CXX object src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/saga.cpp.o
/home/ray/Downloads/saga-gis-code/saga-gis/src/saga_core/saga_gui/saga.cpp: In member function ‘bool CSAGA::Set_Busy(bool, const CSG_String&)’:
/home/ray/Downloads/saga-gis-code/saga-gis/src/saga_core/saga_gui/saga.cpp:350:5: error: ‘wxBusyInfoFlags’ was not declared in this scope; did you mean ‘wxBusyInfo’?
350 | wxBusyInfoFlags Flags;
| ^~~~~~~~~~~~~~~
| wxBusyInfo
/home/ray/Downloads/saga-gis-code/saga-gis/src/saga_core/saga_gui/saga.cpp:352:5: error: ‘Flags’ was not declared in this scope
352 | Flags.Parent (g_pSAGA_Frame);
| ^~~~~
make[2]: *** [src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/build.make:505: src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/saga.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:2429: src/saga_core/saga_gui/CMakeFiles/saga_gui.dir/all] Error 2
make: *** [Makefile:130: all] Error 2

In C++ you need to declare the functions before they are used.