private class LocalVarInitVisitor
	super Visitor

	var toolcontext: ToolContext

	# Local variables that are possibly unset (ie local variable without an initial value)
	var maybe_unset_vars: Set[Variable] = new HashSet[Variable]

	fun mark_is_unset(node: AExpr, variable: nullable Variable)
	do
		assert variable != null
		self.maybe_unset_vars.add(variable)
	end

	fun mark_is_set(node: AExpr, variable: nullable Variable)
	do
		assert variable != null
		if not maybe_unset_vars.has(variable) then return

		var flow = node.after_flow_context.as(not null)
		flow.set_vars.add(variable)
	end

	fun check_is_set(node: AExpr, variable: nullable Variable)
	do
		assert variable != null
		if not maybe_unset_vars.has(variable) then return

		var flow = node.after_flow_context.as(not null)
		if not flow.is_variable_set(variable) then
			self.toolcontext.error(node.hot_location, "Error: possibly unset variable `{variable}`.")
			# Remove the variable to avoid repeating errors
			self.maybe_unset_vars.remove(variable)
		end
	end

	redef fun visit(n)
	do
		n.accept_local_var_visitor(self)
	end
end