# Verifiy the validity of the explicit callbacks to Nit
	# also fills the set returned by foreign_callbacks
	fun verify_nitni_callbacks(toolcontext: ToolContext)
	do
		if foreign_callbacks_cache != null then return

		var fcs = new ForeignCallbackSet

		var mmodule = mpropdef.mclassdef.mmodule

		# receiver
		var recv_type = mpropdef.mclassdef.bound_mtype
		fcs.types.add(recv_type)

		# return type
		var rmt = mpropdef.msignature.return_mtype
		if rmt != null then
			if rmt isa MFormalType then
				var mclass_type = mpropdef.mclassdef.bound_mtype
				rmt = rmt.anchor_to(mmodule, mclass_type)
			end
			var mtype = rmt.resolve_for(recv_type, recv_type, mmodule, true)
			fcs.types.add(mtype)
		end

		# params
		for p in mpropdef.msignature.mparameters do
			var mtype = p.mtype.resolve_for(recv_type, recv_type, mmodule, true)
			if mtype isa MFormalType then
				var mclass_type = mpropdef.mclassdef.bound_mtype
				mtype = mtype.anchor_to(mmodule, mclass_type)
			end
			fcs.types.add( mtype )
		end

		# explicit callbacks
		if n_extern_calls != null then
			for ec in n_extern_calls.n_extern_calls do
				ec.verify_and_collect(self, fcs, toolcontext)
			end
		end

		# store result
		foreign_callbacks_cache = fcs
	end