feat: delay emptying dist/ folder in svelte-package (#10514)

.changeset/red-dots-notice.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/package': patch
+---
+
+fix: delay emptying `dist/` folder

packages/package/src/index.js

@@ -22,25 +22,29 @@ export async function build(options) {
  * @param {(name: string, code: string) => void} analyse_code
  */
 async function do_build(options, analyse_code) {
-	const { input, output, extensions, alias } = normalize_options(options);
+	const { input, output, temp, extensions, alias } = normalize_options(options);
 
 	if (!fs.existsSync(input)) {
 		throw new Error(`${path.relative('.', input)} does not exist`);
 	}
 
-	rimraf(output);
-	mkdirp(output);
+	rimraf(temp);
+	mkdirp(temp);
 
 	const files = scan(input, extensions);
 
 	if (options.types) {
-		await emit_dts(input, output, options.cwd, alias, files);
+		await emit_dts(input, temp, options.cwd, alias, files);
 	}
 
 	for (const file of files) {
-		await process_file(input, output, file, options.config.preprocess, alias, analyse_code);
+		await process_file(input, temp, file, options.config.preprocess, alias, analyse_code);
 	}
 
+	rimraf(output);
+	mkdirp(output);
+	copy(temp, output);
+
 	console.log(
 		colors
 			.bold()
@@ -145,6 +149,11 @@ export async function watch(options) {
 function normalize_options(options) {
 	const input = path.resolve(options.cwd, options.input);
 	const output = path.resolve(options.cwd, options.output);
+	const temp = path.resolve(
+		options.cwd,
+		options.config.kit?.outDir ?? '.svelte-kit',
+		'__package__'
+	);
 	const extensions = options.config.extensions ?? ['.svelte'];
 
 	const alias = {
@@ -155,6 +164,7 @@ function normalize_options(options) {
 	return {
 		input,
 		output,
+		temp,
 		extensions,
 		alias
 	};

packages/package/src/types.d.ts

@@ -12,6 +12,7 @@ export interface Options {
 			files?: {
 				lib?: string;
 			};
+			outDir?: string;
 		};
 		preprocess?: PreprocessorGroup;
 	};