# Propagate the variance constraints on `covar_classes`, `covar_pt`, `contravar_classes` and `contravar_pt`
	#
	# The algorithm uses a fixed-point approach on the covariance/contravariance rules.
	fun propagate
	do
		# Classes to add to the `covar_classes` set at the end of an iteration
		var new_covar = new Array[MClassType]
		# Classes to add to the `contravar_classes` set at the end of an iteration
		var new_contravar = new Array[MClassType]
		# Does a modification occurred, so that another iteration is needed?
		var dirty = true
		# Total number of iterations
		var cpt = 0

		while dirty do
			cpt += 1
			dirty = false
			new_covar.clear
			new_contravar.clear

			# Process the generic types in a covariant position
			for c in covar_classes do for i in [0..c.mclass.arity[ do
				# The type used in the argument
				var ta = c.arguments[i].undecorate
				# The associated formal parameter
				var tp = c.mclass.mparameters[i]

				if not ta.need_anchor then
					# Nothing to do
				else if ta isa MParameterType then
					# COVAR * COVAR = COVAR
					if covar_pt.has(tp) and not covar_pt.has(ta) then
						covar_pt.add(ta)
						dirty = true
					end
					# COVAR * CONTRAVAR = CONTRAVAR
					if contravar_pt.has(tp) and not contravar_pt.has(ta) then
						contravar_pt.add(ta)
						dirty = true
					end
				else if ta isa MVirtualType then
					# TODO?
				else if ta isa MClassType then
					# COVAR * COVAR = COVAR
					if covar_pt.has(tp) and not covar_classes.has(ta) then
						new_covar.add ta
						dirty = true
					end
					# COVAR * CONTRAVAR = CONTRAVAR
					if contravar_pt.has(tp) and not contravar_classes.has(ta) then
						new_contravar.add ta
						dirty = true
					end
				end
			end

			# Process the generic types in a contravariant position
			for c in contravar_classes do for i in [0..c.mclass.arity[ do
				# The type used in the argument
				var ta = c.arguments[i].undecorate
				# The associated formal parameter
				var tp = c.mclass.mparameters[i]

				if not ta.need_anchor then
					# Nothing to do
				else if ta isa MParameterType then
					# CONTRAVAR * CONTRAVAR = COVAR
					if contravar_pt.has(tp) and not covar_pt.has(ta) then
						covar_pt.add(ta)
						dirty = true
					end
					# CONTRAVAR * COVAR = CONTRAVAR
					if covar_pt.has(tp) and not contravar_pt.has(ta) then
						contravar_pt.add(ta)
						dirty = true
					end
				else if ta isa MVirtualType then
					# TODO?
				else if ta isa MClassType then
					# CONTRAVAR * CONTRAVAR = COVAR
					if contravar_pt.has(tp) and not covar_classes.has(ta) then
						new_covar.add ta
						dirty = true
					end
					# CONTRAVAR * COVAR = CONTRAVAR
					if covar_pt.has(tp) and not contravar_classes.has(ta) then
						new_contravar.add ta
						dirty = true
					end
				end
			end

			covar_classes.add_all(new_covar)
			contravar_classes.add_all(new_contravar)
		end
	end