fix: return ast from compile

Was returned from Svelte 4's compile method, and language tools uses it in various places for perf reasons (not doing double parses unnecessarily if you need both)

Author: dummdidumm

.changeset/silly-balloons-deny.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: return ast from `compile`

packages/svelte/src/compiler/index.js

@@ -28,7 +28,7 @@ export function compile(source, options) {
 		});
 
 		const analysis = analyze_component(parsed, combined_options);
-		const result = transform_component(analysis, source, combined_options);
+		const result = transform_component(parsed, analysis, source, combined_options);
 		return result;
 	} catch (e) {
 		if (e instanceof CompileError) {
@@ -45,7 +45,7 @@ export function compile(source, options) {
  * https://svelte.dev/docs/svelte-compiler#svelte-compile
  * @param {string} source The component source code
  * @param {import('#compiler').ModuleCompileOptions} options
- * @returns {import('#compiler').CompileResult}
+ * @returns {import('#compiler').ModuleCompileResult}
  */
 export function compileModule(source, options) {
 	try {

packages/svelte/src/compiler/phases/3-transform/index.js

@@ -5,20 +5,22 @@ import { client_component, client_module } from './client/transform-client.js';
 import { getLocator } from 'locate-character';
 
 /**
+ * @param {import('#compiler').Root} ast
  * @param {import('../types').ComponentAnalysis} analysis
  * @param {string} source
  * @param {import('#compiler').ValidatedCompileOptions} options
  * @returns {import('#compiler').CompileResult}
  */
-export function transform_component(analysis, source, options) {
+export function transform_component(ast, analysis, source, options) {
 	if (options.generate === false) {
 		return {
 			js: /** @type {any} */ (null),
 			css: null,
 			warnings: transform_warnings(source, options.filename, analysis.warnings),
 			metadata: {
 				runes: analysis.runes
-			}
+			},
+			ast
 		};
 	}
 
@@ -50,21 +52,21 @@ export function transform_component(analysis, source, options) {
 		warnings: transform_warnings(source, options.filename, analysis.warnings),
 		metadata: {
 			runes: analysis.runes
-		}
+		},
+		ast
 	};
 }
 
 /**
  * @param {import('../types').Analysis} analysis
  * @param {string} source
  * @param {import('#compiler').ValidatedModuleCompileOptions} options
- * @returns {import('#compiler').CompileResult}
+ * @returns {import('#compiler').ModuleCompileResult}
  */
 export function transform_module(analysis, source, options) {
 	if (options.generate === false) {
 		return {
 			js: /** @type {any} */ (null),
-			css: null,
 			warnings: transform_warnings(source, analysis.name, analysis.warnings),
 			metadata: {
 				runes: true
@@ -89,7 +91,6 @@ export function transform_module(analysis, source, options) {
 
 	return {
 		js: print(program, {}),
-		css: null,
 		warnings: transform_warnings(source, analysis.name, analysis.warnings),
 		metadata: {
 			runes: true

packages/svelte/src/compiler/types/index.d.ts

@@ -11,24 +11,17 @@ import type { SourceMap } from 'magic-string';
 import type { Context } from 'zimmerframe';
 import type { Scope } from '../phases/scope.js';
 import * as Css from './css.js';
-import type { EachBlock, Namespace, SvelteNode } from './template.js';
+import type { EachBlock, Namespace, Root, SvelteNode } from './template.js';
 
-/** The return value of `compile` from `svelte/compiler` */
-export interface CompileResult {
+/** The return value of `compileModule` from `svelte/compiler` */
+export interface ModuleCompileResult {
 	/** The compiled JavaScript */
 	js: {
 		/** The generated code */
 		code: string;
 		/** A source map */
 		map: SourceMap;
 	};
-	/** The compiled CSS */
-	css: null | {
-		/** The generated code */
-		code: string;
-		/** A source map */
-		map: SourceMap;
-	};
 	/**
 	 * An array of warning objects that were generated during compilation. Each warning has several properties:
 	 * - `code` is a string identifying the category of warning
@@ -48,6 +41,19 @@ export interface CompileResult {
 	};
 }
 
+/** The return value of `compile` from `svelte/compiler` */
+export interface CompileResult extends ModuleCompileResult {
+	/** The compiled CSS */
+	css: null | {
+		/** The generated code */
+		code: string;
+		/** A source map */
+		map: SourceMap;
+	};
+	/** The AST */
+	ast: Root;
+}
+
 export interface Warning {
 	start?: Location;
 	end?: Location;

packages/svelte/types/index.d.ts

@@ -502,7 +502,7 @@ declare module 'svelte/compiler' {
 	 * https://svelte.dev/docs/svelte-compiler#svelte-compile
 	 * @param source The component source code
 	 * */
-	export function compileModule(source: string, options: ModuleCompileOptions): CompileResult;
+	export function compileModule(source: string, options: ModuleCompileOptions): ModuleCompileResult;
 	/**
 	 * The parse function parses a component, returning only its abstract syntax tree.
 	 *
@@ -519,22 +519,15 @@ declare module 'svelte/compiler' {
 	 * @deprecated Replace this with `import { walk } from 'estree-walker'`
 	 * */
 	function walk(): never;
-	/** The return value of `compile` from `svelte/compiler` */
-	interface CompileResult {
+	/** The return value of `compileModule` from `svelte/compiler` */
+	interface ModuleCompileResult {
 		/** The compiled JavaScript */
 		js: {
 			/** The generated code */
 			code: string;
 			/** A source map */
 			map: SourceMap;
 		};
-		/** The compiled CSS */
-		css: null | {
-			/** The generated code */
-			code: string;
-			/** A source map */
-			map: SourceMap;
-		};
 		/**
 		 * An array of warning objects that were generated during compilation. Each warning has several properties:
 		 * - `code` is a string identifying the category of warning
@@ -554,6 +547,19 @@ declare module 'svelte/compiler' {
 		};
 	}
 
+	/** The return value of `compile` from `svelte/compiler` */
+	interface CompileResult extends ModuleCompileResult {
+		/** The compiled CSS */
+		css: null | {
+			/** The generated code */
+			code: string;
+			/** A source map */
+			map: SourceMap;
+		};
+		/** The AST */
+		ast: Root;
+	}
+
 	interface Warning {
 		start?: Location;
 		end?: Location;