How to build from sources?

[de11833]

I cloned the branch primary but I'm not able to run a build.

I set the path cmake.dir in local.properties properly.

I also read the Readme.md and followed the instructions under BUILD to copy some libraries though I didn't know why.

I received the folling error:

CMake Error at CMakeLists.txt:49 (add_library):
Cannot find source file:

backupinfo.cpp

Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm
.ccm .cxxm .c++m .h .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90
.f95 .f03 .hip .ispc

CMake Error at CMakeLists.txt:49 (add_library):
No SOURCES given to target: g

The file backupinfo.cpp seems it doesn't exist, I searched for it but didn't find it.

Any idea?

I'm also missing all C/C++-files in Android-Studio, though the files are all there under Common/src/main.

Btw: why shoud I copy libraries from the apk back into the source tree? Shouldn't these libraries are the artefacts of the build process?