fun diff(toolcontext: ToolContext, ref: ManPage) do
		if name != ref.name then
			toolcontext.warning(mmodule.location, "diff-man",
				"Warning: outdated man description. " +
				"Expected `{ref.name or else ""}` got `{name or else ""}`.")
		end
		if synopsis != ref.synopsis then
			toolcontext.warning(mmodule.location, "diff-man",
				"Warning: outdated man synopsis. " +
				"Expected `{ref.synopsis or else ""}` got `{synopsis or else ""}`.")
		end
		for name, desc in options do
			if not ref.options.has_key(name) then
				toolcontext.warning(mmodule.location, "diff-man",
					"Warning: unknown man option `{name}`.`")
				continue
			end
			var ref_desc = ref.options[name]
			if desc != ref_desc then
				toolcontext.warning(mmodule.location, "diff-man",
					"Warning: outdated man option description. Expected `{ref_desc}` got `{desc}`.")
			end
		end
		for ref_name, ref_desc in ref.options do
			if not options.has_key(ref_name) then
				toolcontext.warning(mmodule.location, "diff-man",
					"Warning: missing man option `{ref_name}`.`")
			end
		end
	end