private fun check_redef_property_visibility(modelbuilder: ModelBuilder, nvisibility: nullable AVisibility, mprop: MProperty)
	do
		if nvisibility == null then return
		var mvisibility = nvisibility.mvisibility
		if mvisibility != mprop.visibility and mvisibility != public_visibility then
				modelbuilder.error(nvisibility, "Error: redefinition changed the visibility from `{mprop.visibility}` to `{mvisibility}`.")
		end
	end