wip: deep search for svelte dependencies

packages/playground/optimizedeps-include/vite.config.js

@@ -12,9 +12,6 @@ const SVELTE_IMPORTS = [
 export default defineConfig(({ command, mode }) => {
 	const isProduction = mode === 'production';
 	return {
-		optimizeDeps: {
-			include: [...SVELTE_IMPORTS]
-		},
 		plugins: [svelte()],
 		build: {
 			minify: isProduction

packages/vite-plugin-svelte/src/utils/dependencies.ts

@@ -0,0 +1,124 @@
+import { log } from './log';
+import path from 'path';
+import fs from 'fs';
+import { createRequire } from 'module';
+
+export function findSvelteDependencies(
+	root: string,
+	cwdFallback = true
+): Record<string, SvelteDependency[]> {
+	log.debug(`findSvelteDependencies: searching svelte dependencies in ${root}`);
+
+	const pkgFile = path.join(root, 'package.json');
+	if (!fs.existsSync(pkgFile)) {
+		if (cwdFallback) {
+			const cwd = process.cwd();
+			if (root !== cwd) {
+				log.debug(`no package.json found in  vite root ${root}`);
+				return findSvelteDependencies(cwd, false);
+			}
+		}
+		log.debug(`no package.json found, search failed`);
+		return {};
+	}
+
+	const stack = [{ dir: root, depPath: [] as string[] }];
+	// name->SvelteDependency[]
+	const result: Record<string, SvelteDependency[]> = {};
+	const doNotScan = new Set<string>([
+		'svelte',
+		'vite',
+		'@sveltejs/kit',
+		'@sveltejs/vite-plugin-svelte'
+	]);
+
+	while (stack.length > 0) {
+		const { dir, depPath } = stack.shift()!;
+		const pkg = parsePkg(dir);
+		if (!pkg) {
+			continue;
+		}
+		if (dir !== root) {
+			if (!isSvelte(pkg)) {
+				doNotScan.add(pkg.name);
+				continue;
+			}
+			if (!result[pkg.name]) {
+				result[pkg.name] = [];
+			}
+			result[pkg.name].push({ name: pkg.name, pkg, dir, paths: [depPath] });
+		}
+
+		const pkgRequire = createRequire(dir);
+		const deps = [
+			...Object.keys(pkg.dependencies || {}),
+			...Object.keys(pkg.devDependencies || {})
+		];
+		const resolvedDeps = deps.map((dep) => ({ name: dep, dir: getDependencyDir(pkgRequire, dep) }));
+		const nestedDepPath = [...depPath, pkg.name];
+		for (const dep of resolvedDeps) {
+			if (doNotScan.has(dep.name)) {
+				continue;
+			}
+			const existingResult = result[dep.name]?.find((x) => x.dir === dep.dir);
+			if (existingResult) {
+				// we already have this, just add an additional path to it
+				existingResult.paths.push(nestedDepPath);
+			} else {
+				stack.push({ dir: dep.dir, depPath: nestedDepPath });
+			}
+		}
+	}
+	return result;
+}
+
+// TODO better implementation
+function getDependencyDir(pkgRequire: NodeRequire, dep: string) {
+	try {
+		return path.dirname(pkgRequire.resolve(path.join(dep, 'package.json')));
+	} catch (e) {
+		// does not export package.json, walk up parent directories of default export until we find the one named like the package
+		let dir = path.dirname(pkgRequire.resolve(path.join(dep)));
+		while (dir && path.basename(dir) !== dep) {
+			const parent = path.dirname(dir);
+			if (parent !== dir) {
+				dir = parent;
+			}
+		}
+		return dir;
+	}
+}
+
+function parsePkg(dir: string) {
+	const pkgFile = path.join(dir, 'package.json');
+	try {
+		return JSON.parse(fs.readFileSync(pkgFile, 'utf-8'));
+	} catch (e) {
+		log.warn(`failed to parse ${pkgFile}`, e);
+		return null;
+	}
+}
+
+function isSvelte(pkg: Pkg) {
+	return pkg.svelte || pkg.peerDependencies?.svelte;
+}
+
+export interface SvelteDependency {
+	name: string;
+	dir: string;
+	pkg: Pkg;
+	paths: string[][];
+}
+
+export interface Pkg {
+	name: string;
+	svelte?: string;
+	dependencies?: DependencyList;
+	peerDependencies?: DependencyList;
+	devDependencies?: DependencyList;
+	[key: string]: any;
+}
+
+export interface DependencyList {
+	[key: string]: string;
+}

packages/vite-plugin-svelte/src/utils/options.ts

@@ -13,6 +13,7 @@ import {
 	// eslint-disable-next-line node/no-missing-import
 } from 'svelte/types/compiler/preprocess';
 import path from 'path';
+import { findSvelteDependencies } from './dependencies';
 
 const knownOptions = new Set([
 	'configFile',
@@ -192,6 +193,14 @@ export function buildExtraViteConfig(
 	} else {
 		log.debug('"svelte" is excluded in optimizeDeps.exclude, skipped adding it to include.');
 	}
+
+	const svelteDeps = findSvelteDependencies(options.root);
+	console.log('svelteDeps', svelteDeps);
+	const svelteDepsToExclude = Object.keys(svelteDeps).filter(
+		(dep) => !config?.optimizeDeps?.include?.includes(dep)
+	);
+	log.debug(`automatically excluding found svelte dependencies: ${svelteDepsToExclude.join(', ')}`);
+	exclude.push(...svelteDepsToExclude);
 	const extraViteConfig: Partial<UserConfig> = {
 		optimizeDeps: {
 			include,