There are two myst.cpp files in two different directories. So in case symbian building system
outputs the object files in the same directory there became clashes
and one object file is lost.
I renamed one in mohawk\myst_stacks to myst_stack.cpp and compilation was fine.
(Thaks to Johannes Schickel for tips)
This is not a bug in Myst, it rather seems that the Symbian build system is not set up properly.
Symbian build sustem hasn't any settings for this. It compiles or not out of box.
This issue breaks portability. I did not know what to do while you says about two myst.cpp.