mention that running under windows is not advised (cloudflare#407)

docs/supported.md

@@ -1,5 +1,9 @@
 # Supported Versions and Features
 
+## Operating Systems
+
+`@cloudflare/next-on-pages` can be run on Linux, Mac OS and Windows but its usage under the latter is discouraged as we've noticed that one of the CLI's dependencies, the [Vercel CLI](https://vercel.com/docs/cli) (used to build the Next.js application) seems not to work reliably on Windows. If you need to run `@cloudflare/next-on-pages` on Windows we advise you to run it under the [Windows Subsystem for Linux](https://learn.microsoft.com/en-us/windows/wsl/).
+
 ## Supported Next.js versions
 
 Based on manual testing, it seems like the latest Next.js version (`13.4.2` at the time of writing) is supported.

src/buildApplication/packageManagerUtils.ts

@@ -2,7 +2,7 @@ import { execFileSync, spawn } from 'child_process';
 import { readFile } from 'fs/promises';
 import YAML from 'js-yaml';
 import { cliError, cliWarn } from '../cli';
-import { validateFile } from '../utils';
+import { isWindows, validateFile } from '../utils';
 
 /**
  * Gets the current package manager for the project.
@@ -250,15 +250,6 @@ export async function getExecStr(
 	return `${execCmd ?? baseCmd} ${args.join(' ') ?? ''}`.trim();
 }
 
-/**
- * Checks whether the current platform is Windows.
- *
- * @returns Whether the current platform is Windows.
- */
-function isWindows(): boolean {
-	return process.platform === 'win32';
-}
-
 export type PackageManager =
 	| 'bun'
 	| 'pnpm'

src/index.ts

@@ -4,7 +4,7 @@ import type { CliOptions } from './cli';
 import { cliWarn, cliError } from './cli';
 import { cliLog, parseCliArgs, printCliHelpMessage, printEnvInfo } from './cli';
 import { buildApplication } from './buildApplication';
-import { nextOnPagesVersion } from './utils';
+import { isWindows, nextOnPagesVersion } from './utils';
 
 const limit = pLimit(1);
 
@@ -30,6 +30,16 @@ async function runNextOnPages(): Promise<void> {
 		return;
 	}
 
+	if (isWindows()) {
+		cliWarn(
+			`Warning: It seems like you're on a Windows system, the Vercel CLI (run by @cloudflare/next-on-pages
+			to build your application) seems not to work reliably on Windows so if you experience issues during
+			the build process please try switching to a different operating system or running
+			@cloudflare/next-on-pages under the Windows Subsystem for Linux`,
+			{ spaced: true },
+		);
+	}
+
 	if (args.experimentalMinify) {
 		cliWarn(
 			`

src/utils/index.ts

@@ -2,3 +2,4 @@ export * from './fs';
 export * from './version';
 export * from './routing';
 export * from './str';
+export * from './os';

src/utils/os.ts

@@ -0,0 +1,8 @@
+/**
+ * Checks whether the current platform is Windows.
+ *
+ * @returns Whether the current platform is Windows.
+ */
+export function isWindows(): boolean {
+	return process.platform === 'win32';
+}