private fun accept_ast_validation(v: ASTValidationVisitor)
	do
		var parent = self.parent
		var path = v.path

		if path.length > 0 then
			var path_parent = v.path.first
			if parent == null then
				self.parent = path_parent
				#debug "PARENT: expected parent: {path_parent}"
				v.seen.add(self)
			else if parent != path_parent then
				self.parent = path_parent
				if v.seen.has(self) then
					debug "DUPLICATE (NOTATREE): already seen node with parent {parent} now with {path_parent}."
				else
					v.seen.add(self)
					debug "PARENT: expected parent: {path_parent}, got {parent}"
				end
			end
		end

		if not isset _location then
			#debug "LOCATION: unlocated node {v.path.join(", ")}"
			_location = self.parent.location
		end

		path.unshift(self)
		visit_all(v)
		path.shift
	end