feat(rolldown-vite): enable optimization.inlineConst by default

.changeset/all-colts-dig.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/vite-plugin-svelte': minor
+---
+
+feat(rolldown-vite): enable `optimization.inlineConst` by default to ensure treeshaking works with esm-env in svelte

packages/vite-plugin-svelte/__tests__/svelte-version.spec.js

@@ -2,25 +2,54 @@ import { describe, it, expect } from 'vitest';
 import { gte } from '../src/utils/svelte-version.js';
 
 describe('gte', () => {
+	it('returns false for smaller tag', () => {
+		expect(gte('1.2.3-next.1', '1.2.3-next.2')).toBe(false);
+	});
+	it('returns false for tag vs no tag', () => {
+		expect(gte('1.2.3-next.0', '1.2.3')).toBe(false);
+	});
 	it('returns false for smaller patch', () => {
+		expect(gte('1.2.2-next.0', '1.2.3')).toBe(false);
 		expect(gte('1.2.2', '1.2.3')).toBe(false);
 	});
 	it('returns false for smaller minor', () => {
+		expect(gte('1.1.4-next.0', '1.2.3')).toBe(false);
 		expect(gte('1.1.4', '1.2.3')).toBe(false);
+		expect(gte('1.1', '1.2.3')).toBe(false);
 	});
 	it('returns false for smaller major', () => {
+		expect(gte('0.3.4-next.0', '1.2.3')).toBe(false);
 		expect(gte('0.3.4', '1.2.3')).toBe(false);
+		expect(gte('0.3', '1.2.3')).toBe(false);
+		expect(gte('0', '1.2.3')).toBe(false);
 	});
 	it('returns true for equal', () => {
+		expect(gte('1.2.3-next.1', '1.2.3-next.1')).toBe(true);
+	});
+	it('returns true for equal without tag', () => {
 		expect(gte('1.2.3', '1.2.3')).toBe(true);
+		expect(gte('1.2', '1.2.0')).toBe(true);
+		expect(gte('1.2', '1.2')).toBe(true);
+		expect(gte('1', '1.0')).toBe(true);
+		expect(gte('1', '1.0.0')).toBe(true);
+	});
+	it('returns true for larger tag', () => {
+		expect(gte('1.2.3-next.2', '1.2.3-next.1')).toBe(true);
+	});
+	it('returns true for no tag vs tag', () => {
+		expect(gte('1.2.3', '1.2.3-next.0')).toBe(true);
 	});
 	it('returns true for larger patch', () => {
 		expect(gte('1.2.4', '1.2.3')).toBe(true);
+		expect(gte('1.2.4-next.0', '1.2.3')).toBe(true);
 	});
 	it('returns true for larger minor', () => {
 		expect(gte('1.3.1', '1.2.3')).toBe(true);
+		expect(gte('1.3', '1.2.3')).toBe(true);
 	});
 	it('returns true for larger major', () => {
 		expect(gte('2.0.0', '1.2.3')).toBe(true);
+		expect(gte('2.0', '1.2.3')).toBe(true);
+		expect(gte('2', '1.2.3')).toBe(true);
 	});
 });

packages/vite-plugin-svelte/src/plugins/configure.js

@@ -12,6 +12,7 @@ import {
 } from '../utils/options.js';
 import { buildIdFilter, buildIdParser } from '../utils/id.js';
 import { createCompileSvelte } from '../utils/compile.js';
+import { gte } from '../utils/svelte-version.js';
 
 // @ts-ignore rolldownVersion
 const { version: viteVersion, rolldownVersion } = vite;
@@ -58,7 +59,39 @@ export function configure(api, inlineOptions) {
 				preOptions = await preResolveOptions(inlineOptions, config, configEnv);
 				// extra vite config
 				const extraViteConfig = await buildExtraViteConfig(preOptions, config);
+
+				if (
+					rolldownVersion &&
+					configEnv.command === 'build' &&
+					gte(rolldownVersion, '1.0.0-beta.35') // inlineConst received a critical bugfix in 1.0.0-beta.35
+				) {
+					extraViteConfig.build ??= {};
+					// rename rollupOptions to rolldownOptions
+					//@ts-ignore rolldownOptions only exists in rolldown-vite
+					extraViteConfig.build.rolldownOptions = extraViteConfig.build.rollupOptions || {};
+					delete extraViteConfig.build.rollupOptions;
+					// read user config inlineConst value
+					const inlineConst =
+						//@ts-ignore optimization only exists in rolldown-vite
+						config.build?.rolldownOptions?.optimization?.inlineConst ??
+						//@ts-ignore optimization only exists in rolldown-vite
+						config.build?.rollupOptions?.optimization?.inlineConst;
+
+					if (inlineConst == null) {
+						// set inlineConst build optimization for esm-env
+						//@ts-ignore rolldownOptions only exists in rolldown-vite
+						extraViteConfig.build.rolldownOptions.optimization ??= {};
+						//@ts-ignore rolldownOptions only exists in rolldown-vite
+						extraViteConfig.build.rolldownOptions.optimization.inlineConst = true;
+					} else if (inlineConst === false) {
+						log.warn(
+							'Your rolldown config contains `optimization.inlineConst: false`. This can lead to increased bundle size and leaked server code in client build.'
+						);
+					}
+				}
+
 				log.debug('additional vite config', extraViteConfig, 'config');
+
 				return extraViteConfig;
 			}
 		},

packages/vite-plugin-svelte/src/utils/svelte-version.js

@@ -6,15 +6,34 @@ import { VERSION } from 'svelte/compiler';
 export const isSvelteWithAsync = gte(VERSION, '5.36.0');
 
 /**
- * compare semver versions, does not include comparing tags (-next.xy is ignored)
+ * split semver string and convert to number, ignores non digits in tag
+ * @param {string} semver
+ * @return {number[]} [major,minor,patch,tag]
+ */
+function splitToNumbers(semver) {
+	const num = semver
+		.replace(/[^\d.-]/g, '')
+		.split(/[.-]+/, 4)
+		.map(Number);
+	while (num.length < 3) {
+		num.push(0);
+	}
+	if (num.length < 4) {
+		num.push(Infinity);
+	}
+	return num;
+}
+
+/**
+ * compare semver versions, tags are compared by their numeric part only
  *
  * @param {string} a semver version
  * @param {string} b semver version
  * @return {boolean} true if a is greater or equal to b
  */
 export function gte(a, b) {
-	const aNum = a.split(/[.-]/, 3).map(Number);
-	const bNum = b.split(/[.-]/, 3).map(Number);
+	const aNum = splitToNumbers(a);
+	const bNum = splitToNumbers(b);
 	for (let i = 0; i < aNum.length; i++) {
 		if (aNum[i] < bNum[i]) {
 			return false;