The issue was: for MacOS/clang, the virtual format-specific
option structs had to be embedded in one compile unit (for RTTI).
In Windows this will lead to link errors since the DLL is not
reachable at build time for the generic reader/writer configuration in
the buddy tools.
The solution is to use GSI methods (provided for scripting) to
set the reader/writer options in a generic way that does not
require linking against the plugin DLLs.
Unlike Linux, RTTI does not work in MacOS/clang when the classes
originate from different compile units. I think that Linux's C++
runtime not only checks for identical vtable, but alternatively
for same name. On MacOS, dynamic_cast will fail instead. This fix
solves this issue by placing the important steam format option
specializations into a single specific shared object (the DB plugin).
The text writer was made "normalizing": it will introduce
a certain element order (string sorting). This way, OASIS
files can be compared against golden data without
changes in the order due to different implementation of
hash containers.