fix: correctly resolve paths provided through Wrangler config on Windows (#13671)

* fix

fixes #13667

This PR uses the non-posix relative() method so that it correctly resolves when used with Windows paths that may be provided through the Wrangler configuration. It also converts the path to a POSIX path before embedding them into the worker script since backslashes get interpreted as escape characters and are lost in the process.

Also includes a minor fix where if the user had pages_build_output_dir set in their wrangler configuration, the adapter wasn't writing the worker to that directory (Cloudflare Pages expects the worker and assets to be in the same directory).

Author: eltigerchino

.changeset/bright-houses-kick.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+fix: correctly write the worker to the `pages_build_output_dir` path if set in the Wrangler configuration path

.changeset/gentle-parrots-clap.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-cloudflare': patch
+---
+
+fix: correctly resolve paths provided by the Wrangler config on Windows

packages/adapter-cloudflare/index.js

@@ -37,6 +37,7 @@ export default function (options = {}) {
 			if (building_for_cloudflare_pages) {
 				if (wrangler_config.pages_build_output_dir) {
 					dest = wrangler_config.pages_build_output_dir;
+					worker_dest = `${dest}/_worker.js`;
 				}
 			} else {
 				if (wrangler_config.main) {
@@ -92,8 +93,11 @@ export default function (options = {}) {
 			);
 			builder.copy(`${files}/worker.js`, worker_dest, {
 				replace: {
-					SERVER: `${path.posix.relative(worker_dest_dir, builder.getServerDirectory())}/index.js`,
-					MANIFEST: `${path.posix.relative(worker_dest_dir, tmp)}/manifest.js`,
+					// the paths returned by the Wrangler config might be Windows paths,
+					// so we need to convert them to POSIX paths or else the backslashes
+					// will be interpreted as escape characters and create an incorrect import path
+					SERVER: `${posixify(path.relative(worker_dest_dir, builder.getServerDirectory()))}/index.js`,
+					MANIFEST: `${posixify(path.relative(worker_dest_dir, tmp))}/manifest.js`,
 					ASSETS: assets_binding
 				}
 			});
@@ -309,3 +313,8 @@ function is_building_for_cloudflare_pages(wrangler_config) {
 		!wrangler_config.assets
 	);
 }
+
+/** @param {string} str */
+function posixify(str) {
+	return str.replace(/\\/g, '/');
+}