Return type inconsistency (when using libffi?)

[vaartis]

There seems to be an inconsistency in return types of functions that are seemingly same in the C header.

cpShape* cpCircleShapeNew(cpBody *body, cpFloat radius, cpVect offset);
cpShape* cpSegmentShapeNew(cpBody *body, cpVect a, cpVect b, cpFloat radius);

these return a raw pointer, instead of a wrapper

cpShape* cpBoxShapeNew(cpBody *body, cpFloat width, cpFloat height, cpFloat radius);

this returns a wrapped object.

Could this somehow be connected to libffi and passing cpVect by-value?