[fix] resolve $lib alias when packaging

Fixes the 90% case of #1950

.changeset/rich-seahorses-walk.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Resolve \$lib alias when packaging

packages/kit/src/packaging/index.js

@@ -14,11 +14,19 @@ const essential_files = ['README', 'LICENSE', 'CHANGELOG', '.gitignore', '.npmig
  * @param {string} cwd
  */
 export async function make_package(config, cwd = process.cwd()) {
-	rimraf(path.join(cwd, config.kit.package.dir));
+	const abs_package_dir = path.join(cwd, config.kit.package.dir);
+	rimraf(abs_package_dir);
 
 	if (config.kit.package.emitTypes) {
 		// Generate type definitions first so hand-written types can overwrite generated ones
 		await emit_dts(config);
+		// Resolve aliases, TS leaves them as-is
+		const files = walk(abs_package_dir);
+		for (const file of files) {
+			const filename = path.join(abs_package_dir, file);
+			const source = fs.readFileSync(filename, 'utf8');
+			fs.writeFileSync(filename, resolve_$lib_alias(file, source, config));
+		}
 	}
 
 	const files_filter = create_filter(config.kit.package.files);
@@ -46,7 +54,7 @@ export async function make_package(config, cwd = process.cwd()) {
 
 		if (!files_filter(file.replace(/\\/g, '/'))) {
 			const dts_file = (svelte_ext ? file : file.slice(0, -ext.length)) + '.d.ts';
-			const dts_path = path.join(cwd, config.kit.package.dir, dts_file);
+			const dts_path = path.join(abs_package_dir, dts_file);
 			if (fs.existsSync(dts_path)) fs.unlinkSync(dts_path);
 			continue;
 		}
@@ -70,7 +78,7 @@ export async function make_package(config, cwd = process.cwd()) {
 			// TypeScript's declaration emit won't copy over the d.ts files, so we do it here
 			out_file = file;
 			out_contents = source;
-			if (fs.existsSync(path.join(cwd, config.kit.package.dir, out_file))) {
+			if (fs.existsSync(path.join(abs_package_dir, out_file))) {
 				console.warn(
 					'Found already existing file from d.ts generation for ' +
 						out_file +
@@ -84,8 +92,9 @@ export async function make_package(config, cwd = process.cwd()) {
 			out_file = file;
 			out_contents = source;
 		}
+		out_contents = resolve_$lib_alias(out_file, out_contents, config);
 
-		write(path.join(cwd, config.kit.package.dir, out_file), out_contents);
+		write(path.join(abs_package_dir, out_file), out_contents);
 
 		if (exports_filter(file)) {
 			const original = `$lib/${file.replace(/\\/g, '/')}`;
@@ -104,7 +113,7 @@ export async function make_package(config, cwd = process.cwd()) {
 	}
 
 	pkg.exports = { ...generated, ...pkg.exports };
-	write(path.join(cwd, config.kit.package.dir, 'package.json'), JSON.stringify(pkg, null, '  '));
+	write(path.join(abs_package_dir, 'package.json'), JSON.stringify(pkg, null, '  '));
 
 	const whitelist = fs.readdirSync(cwd).filter((file) => {
 		const lowercased = file.toLowerCase();
@@ -114,11 +123,44 @@ export async function make_package(config, cwd = process.cwd()) {
 		const full_path = path.join(cwd, pathname);
 		if (fs.lstatSync(full_path).isDirectory()) continue; // just to be sure
 
-		const package_path = path.join(cwd, config.kit.package.dir, pathname);
+		const package_path = path.join(abs_package_dir, pathname);
 		if (!fs.existsSync(package_path)) fs.copyFileSync(full_path, package_path);
 	}
 }
 
+/**
+ * Resolves the `$lib` alias.
+ *
+ * TODO: make this more generic to also handle
+ * other aliases the user could have defined via `kit.vite.resolve.alias`.
+ *
+ * @param {string} file Relative to the lib root
+ * @param {string} content
+ * @param {import('types/config').ValidatedConfig} config
+ * @returns {string}
+ */
+function resolve_$lib_alias(file, content, config) {
+	/**
+	 * @param {string} match
+	 * @param {string} _
+	 * @param {string} import_path
+	 */
+	const replace_import_path = (match, _, import_path) => {
+		if (!import_path.startsWith('$lib/')) {
+			return match;
+		}
+
+		const full_path = path.join(config.kit.files.lib, file);
+		const full_import_path = path.join(config.kit.files.lib, import_path.slice('$lib/'.length));
+		let resolved = path.relative(path.dirname(full_path), full_import_path).replace(/\\/g, '/');
+		resolved = resolved.startsWith('.') ? resolved : './' + resolved;
+		return match.replace(import_path, resolved);
+	};
+	content = content.replace(/from\s+('|")([^"';,]+?)\1/g, replace_import_path);
+	content = content.replace(/import\s*\(\s*('|")([^"';,]+?)\1\s*\)/g, replace_import_path);
+	return content;
+}
+
 /**
  * @param {string} filename
  * @param {string} source

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/Test.svelte

@@ -0,0 +1,4 @@
+<script lang="ts">
+    import { foo } from './sub/foo';
+    export let bar = foo;
+</script>

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/Test.svelte.d.ts

@@ -0,0 +1,15 @@
+import { SvelteComponentTyped } from 'svelte';
+declare const __propDef: {
+	props: {
+		bar?: import('./sub/foo').Foo;
+	};
+	events: {
+		[evt: string]: CustomEvent<any>;
+	};
+	slots: {};
+};
+export declare type TestProps = typeof __propDef.props;
+export declare type TestEvents = typeof __propDef.events;
+export declare type TestSlots = typeof __propDef.slots;
+export default class Test extends SvelteComponentTyped<TestProps, TestEvents, TestSlots> {}
+export {};

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/baz.d.ts

@@ -0,0 +1,4 @@
+export interface Baz {
+	baz: string;
+}
+export declare const baz: Baz;

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/baz.js

@@ -0,0 +1 @@
+export const baz = { baz: 'baz' };

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/index.d.ts

@@ -0,0 +1 @@
+export { default as Test } from './Test.svelte';

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/index.js

@@ -0,0 +1 @@
+export { default as Test } from './Test.svelte';

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/package.json

@@ -0,0 +1,14 @@
+{
+	"name": "resolve-alias",
+	"version": "1.0.0",
+	"description": "package using $lib alias",
+	"type": "module",
+	"exports": {
+		"./package.json": "./package.json",
+		"./Test.svelte": "./Test.svelte",
+		".": "./index.js",
+		"./baz": "./baz.js",
+		"./sub/bar": "./sub/bar.js",
+		"./sub/foo": "./sub/foo.js"
+	}
+}

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/sub/bar.d.ts

@@ -0,0 +1,2 @@
+export declare const bar1: import('./foo').Foo;
+export declare const bar2: import('../baz').Baz;

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/sub/bar.js

@@ -0,0 +1,4 @@
+import { baz } from '../baz';
+import { foo } from './foo';
+export const bar1 = foo;
+export const bar2 = baz;

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/sub/foo.d.ts

@@ -0,0 +1,4 @@
+export interface Foo {
+	foo: string;
+}
+export declare const foo: Foo;

packages/kit/src/packaging/test/fixtures/resolve-alias/expected/sub/foo.js

@@ -0,0 +1 @@
+export const foo = { foo: 'foo' };

packages/kit/src/packaging/test/fixtures/resolve-alias/package.json

@@ -0,0 +1,5 @@
+{
+	"name": "resolve-alias",
+	"version": "1.0.0",
+	"description": "package using $lib alias"
+}

packages/kit/src/packaging/test/fixtures/resolve-alias/src/app.html

@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<html lang="en">
+	<head>
+		<meta charset="utf-8" />
+		<link rel="icon" href="/favicon.ico" />
+		<meta name="viewport" content="width=device-width, initial-scale=1" />
+		%svelte.head%
+	</head>
+	<body>
+		<div id="svelte">%svelte.body%</div>
+	</body>
+</html>

packages/kit/src/packaging/test/fixtures/resolve-alias/src/lib/Test.svelte

@@ -0,0 +1,5 @@
+<script lang="ts">
+    import { foo } from '$lib/sub/foo';
+
+    export let bar = foo;
+</script>

packages/kit/src/packaging/test/fixtures/resolve-alias/src/lib/baz.ts

@@ -0,0 +1,5 @@
+export interface Baz {
+	baz: string;
+}
+
+export const baz: Baz = { baz: 'baz' };

packages/kit/src/packaging/test/fixtures/resolve-alias/src/lib/index.ts

@@ -0,0 +1 @@
+export { default as Test } from '$lib/Test.svelte';

packages/kit/src/packaging/test/fixtures/resolve-alias/src/lib/sub/bar.ts

@@ -0,0 +1,5 @@
+import { baz } from '$lib/baz';
+import { foo } from '$lib/sub/foo';
+
+export const bar1 = foo;
+export const bar2 = baz;

packages/kit/src/packaging/test/fixtures/resolve-alias/src/lib/sub/foo.ts

@@ -0,0 +1,5 @@
+export interface Foo {
+	foo: string;
+}
+
+export const foo: Foo = { foo: 'foo' };

packages/kit/src/packaging/test/fixtures/resolve-alias/svelte.config.cjs

@@ -0,0 +1,5 @@
+const preprocess = require('svelte-preprocess');
+
+module.exports = {
+	preprocess: preprocess()
+};

packages/kit/src/packaging/test/fixtures/resolve-alias/tsconfig.json

@@ -0,0 +1,30 @@
+{
+	"compilerOptions": {
+		"moduleResolution": "node",
+		"module": "es2020",
+		"lib": ["es2020", "DOM"],
+		"target": "es2019",
+		/**
+			svelte-preprocess cannot figure out whether you have a value or a type, so tell TypeScript
+			to enforce using \`import type\` instead of \`import\` for Types.
+			*/
+		"importsNotUsedAsValues": "error",
+		"isolatedModules": true,
+		"resolveJsonModule": true,
+		/**
+			To have warnings/errors of the Svelte compiler at the correct position,
+			enable source maps by default.
+			*/
+		"sourceMap": true,
+		"esModuleInterop": true,
+		"skipLibCheck": true,
+		"forceConsistentCasingInFileNames": true,
+		"baseUrl": ".",
+		"allowJs": true,
+		"checkJs": true,
+		"paths": {
+			"$lib/*": ["src/lib/*"]
+		}
+	},
+	"include": ["src/**/*.d.ts", "src/**/*.js", "src/**/*.ts", "src/**/*.svelte"]
+}

packages/kit/src/packaging/test/index.js

@@ -109,4 +109,8 @@ test('create package with files.exclude settings', async () => {
 	await test_make_package('files-exclude');
 });
 
+test('create package and resolves $lib alias', async () => {
+	await test_make_package('resolve-alias');
+});
+
 test.run();