Only show compatibility date fallback warning if new version available

When a compatibility date greater than the installed `workerd` version
is selected, Miniflare logs a warning. The intention here is to warn
users if they've set a compatibility date, but haven't updated
`workerd`, so features they've requested won't be available.
The problem is that this warning is only actionable if there's an
update available. This change suppresses the warning if there's no
new version available.

packages/wrangler/src/dev/miniflare.ts

@@ -13,6 +13,7 @@ import { ModuleTypeToRuleType } from "../deployment-bundle/module-collection";
 import { withSourceURLs } from "../deployment-bundle/source-url";
 import { getHttpsOptions } from "../https-options";
 import { logger } from "../logger";
+import { updateCheck } from "../update-check";
 import type { Config } from "../config";
 import type {
 	CfD1Database,
@@ -122,10 +123,19 @@ class WranglerLog extends Log {
 
 	warn(message: string) {
 		// Only log warning about requesting a compatibility date after the workerd
-		// binary's version once
+		// binary's version once, and only if there's an update available.
 		if (message.startsWith("The latest compatibility date supported by")) {
 			if (this.#warnedCompatibilityDateFallback) return;
 			this.#warnedCompatibilityDateFallback = true;
+			return void updateCheck().then((maybeNewVersion) => {
+				if (maybeNewVersion === undefined) return;
+				message += [
+					"",
+					"Features enabled by your requested compatibility date may not be available.",
+					`Upgrade to \`wrangler@${maybeNewVersion}\` to remove this warning.`,
+				].join("\n");
+				super.warn(message);
+			});
 		}
 		super.warn(message);
 	}

packages/wrangler/src/update-check.ts

@@ -2,7 +2,7 @@ import checkForUpdate from "update-check";
 import pkg from "../package.json";
 import type { Result } from "update-check";
 
-export async function updateCheck(): Promise<string | undefined> {
+async function doUpdateCheck(): Promise<string | undefined> {
 	let update: Result | null = null;
 	try {
 		// default cache for update check is 1 day
@@ -14,3 +14,11 @@ export async function updateCheck(): Promise<string | undefined> {
 	}
 	return update?.latest;
 }
+
+// Memoise update check promise, so we can call this multiple times as required
+// without having to prop drill the result. It's unlikely to change through the
+// process lifetime.
+let updateCheckPromise: Promise<string | undefined>;
+export function updateCheck(): Promise<string | undefined> {
+	return (updateCheckPromise ??= doUpdateCheck());
+}