Please tell me the flow of creating TopBar, StatusBar, etc. in C/C++ source code

First, I searched inside the “WM_init” function.
Next, I also cheked that the SpaceType values were registered in the “spacetypes” list using the “ED_spacetype_***” function in “ED_spacetypes_init”.
But then I couldn’t find where the function pointer “create” that SpaceType has is called.
How are SpaceStatusBar, SpaceTopBar, etc. that inherit the SpaceLink type created?
Is the “spacetypes” list involved?