feat: experimental support for Svelte 5 (#2198)

* handle $props()

* handle .svelte.ts files

* remove $ from wordpattern to get proper runes autocompletion; adjust store autocompletion as a consequence

* snippets

* use walk from estree-walker

* more ts-ignore for types that don't exist anymore

* handle the cjs case for 5, too

* fix

* mark test as skipped for now

* lint

* load Svelte 5 compiler if applicable

* bump svelte-preprocess

packages/language-server/package.json

@@ -55,7 +55,7 @@
         "prettier": "~2.8.8",
         "prettier-plugin-svelte": "~2.10.1",
         "svelte": "^3.57.0",
-        "svelte-preprocess": "~5.0.4",
+        "svelte-preprocess": "~5.1.0",
         "svelte2tsx": "workspace:~",
         "typescript": "^5.2.2",
         "vscode-css-languageservice": "~6.2.0",

packages/language-server/src/importPackage.ts

@@ -58,7 +58,7 @@ export function importSvelte(fromPath: string): typeof svelte {
     const pkg = getPackageInfo('svelte', fromPath);
     const main = resolve(pkg.path, 'compiler');
     Logger.debug('Using Svelte v' + pkg.version.full, 'from', main);
-    return dynamicRequire(main + (pkg.version.major === 4 ? '.cjs' : ''));
+    return dynamicRequire(main + (pkg.version.major >= 4 ? '.cjs' : ''));
 }
 
 export function importSveltePreprocess(fromPath: string): typeof sveltePreprocess {

packages/language-server/src/lib/documents/configLoader.ts

@@ -1,5 +1,7 @@
 import { Logger } from '../../logger';
+// @ts-ignore
 import { CompileOptions } from 'svelte/types/compiler/interfaces';
+// @ts-ignore
 import { PreprocessorGroup } from 'svelte/types/compiler/preprocess';
 import { importSveltePreprocess } from '../../importPackage';
 import _glob from 'fast-glob';

packages/language-server/src/plugins/svelte/SvelteDocument.ts

@@ -1,6 +1,8 @@
 import { TraceMap } from '@jridgewell/trace-mapping';
 import type { compile } from 'svelte/compiler';
+// @ts-ignore
 import { CompileOptions } from 'svelte/types/compiler/interfaces';
+// @ts-ignore
 import { PreprocessorGroup, Processed } from 'svelte/types/compiler/preprocess';
 import { Position } from 'vscode-languageserver';
 import { getPackageInfo, importSvelte } from '../../importPackage';
@@ -367,7 +369,7 @@ export class SvelteFragmentMapper implements PositionMapper {
  */
 function wrapPreprocessors(preprocessors: PreprocessorGroup | PreprocessorGroup[] = []) {
     preprocessors = Array.isArray(preprocessors) ? preprocessors : [preprocessors];
-    return preprocessors.map((preprocessor) => {
+    return preprocessors.map((preprocessor: any) => {
         const wrappedPreprocessor: PreprocessorGroup = { markup: preprocessor.markup };
 
         if (preprocessor.script) {
@@ -404,7 +406,7 @@ async function transpile(
     const processedScripts: Processed[] = [];
     const processedStyles: Processed[] = [];
 
-    const wrappedPreprocessors = preprocessors.map((preprocessor) => {
+    const wrappedPreprocessors = preprocessors.map((preprocessor: any) => {
         const wrappedPreprocessor: PreprocessorGroup = { markup: preprocessor.markup };
 
         if (preprocessor.script) {

packages/language-server/src/plugins/svelte/features/SvelteTags.ts

@@ -3,12 +3,12 @@ import { SvelteDocument } from '../SvelteDocument';
 /**
  * Special svelte syntax tags that do template logic.
  */
-export type SvelteLogicTag = 'each' | 'if' | 'await' | 'key';
+export type SvelteLogicTag = 'each' | 'if' | 'await' | 'key' | 'snippet';
 
 /**
  * Special svelte syntax tags.
  */
-export type SvelteTag = SvelteLogicTag | 'html' | 'debug' | 'const';
+export type SvelteTag = SvelteLogicTag | 'html' | 'debug' | 'const' | 'render';
 
 /**
  * For each tag, a documentation in markdown format.
@@ -52,6 +52,13 @@ When used around components, this will cause them to be reinstantiated and reini
 \`{#key expression}...{/key}\`\\
 \\
 https://svelte.dev/docs#template-syntax-key
+`,
+    snippet: `\`{#snippet identifier(parameter)}...{/snippet}\`\\
+Snippets allow you to create reusable UI blocks you can render with the {@render ...} tag.
+They also function as slot props for components.
+`,
+    render: `\`{@render ...}\`\\
+Renders a snippet with the given parameters.
 `,
     html:
         `\`{@html ...}\`\\
@@ -80,9 +87,11 @@ It accepts a comma-separated list of variable names (not arbitrary expressions).
 https://svelte.dev/docs#template-syntax-debug
 `,
     const: `\`{@const ...}\`\\
-TODO
+Defines a local constant}\\
 #### Usage:
 \`{@const a = b + c}\`\\
+\\
+https://svelte.dev/docs/special-tags#const
 `
 };
 
@@ -102,7 +111,8 @@ export function getLatestOpeningTag(
         idxOfLastOpeningTag(content, 'each'),
         idxOfLastOpeningTag(content, 'if'),
         idxOfLastOpeningTag(content, 'await'),
-        idxOfLastOpeningTag(content, 'key')
+        idxOfLastOpeningTag(content, 'key'),
+        idxOfLastOpeningTag(content, 'snippet')
     ];
     const lastIdx = lastIdxs.sort((i1, i2) => i2.lastIdx - i1.lastIdx);
     return lastIdx[0].lastIdx === -1 ? null : lastIdx[0].tag;

packages/language-server/src/plugins/svelte/features/getCodeActions/getQuickfixes.ts

@@ -1,5 +1,6 @@
 import { walk } from 'estree-walker';
 import { EOL } from 'os';
+// @ts-ignore
 import { TemplateNode } from 'svelte/types/compiler/interfaces';
 import {
     CodeAction,

packages/language-server/src/plugins/svelte/features/getCompletions.ts

@@ -125,7 +125,8 @@ function getCompletionsWithRegardToTriggerCharacter(
         return createCompletionItems([
             { tag: 'html', label: 'html' },
             { tag: 'debug', label: 'debug' },
-            { tag: 'const', label: 'const' }
+            { tag: 'const', label: 'const' },
+            { tag: 'render', label: 'render' }
         ]);
     }
 
@@ -143,7 +144,8 @@ function getCompletionsWithRegardToTriggerCharacter(
                 label: 'await then',
                 insertText: 'await $1 then $2}\n\t$3\n{/await'
             },
-            { tag: 'key', label: 'key', insertText: 'key $1}\n\t$2\n{/key' }
+            { tag: 'key', label: 'key', insertText: 'key $1}\n\t$2\n{/key' },
+            { tag: 'snippet', label: 'snippet', insertText: 'snippet $1($2)}\n\t$3\n{/snippet' }
         ]);
     }
 
@@ -207,6 +209,7 @@ function showCompletionWithRegardsToOpenedTags(
         ifOpen: CompletionList;
         awaitOpen: CompletionList;
         keyOpen?: CompletionList;
+        snippetOpen?: CompletionList;
     },
     svelteDoc: SvelteDocument,
     offset: number
@@ -220,6 +223,8 @@ function showCompletionWithRegardsToOpenedTags(
             return on.awaitOpen;
         case 'key':
             return on?.keyOpen ?? null;
+        case 'snippet':
+            return on.snippetOpen ?? null;
         default:
             return null;
     }

packages/language-server/src/plugins/svelte/features/getDiagnostics.ts

@@ -1,3 +1,4 @@
+// @ts-ignore
 import { Warning } from 'svelte/types/compiler/interfaces';
 import { Diagnostic, DiagnosticSeverity, Position, Range } from 'vscode-languageserver';
 import {

packages/language-server/src/plugins/svelte/features/getHoverInfo.ts

@@ -109,10 +109,13 @@ const tagPossibilities: Array<{ tag: SvelteTag | ':else'; values: string[] }> =
     { tag: 'await' as const, values: ['#await', '/await', ':then', ':catch'] },
     // key
     { tag: 'key' as const, values: ['#key', '/key'] },
+    // snippet
+    { tag: 'snippet' as const, values: ['#snippet', '/snippet'] },
     // @
     { tag: 'html' as const, values: ['@html'] },
     { tag: 'debug' as const, values: ['@debug'] },
     { tag: 'const' as const, values: ['@const'] },
+    { tag: 'render' as const, values: ['@render'] },
     // this tag has multiple possibilities
     { tag: ':else' as const, values: [':else'] }
 ];

packages/language-server/src/plugins/typescript/DocumentSnapshot.ts

@@ -1,4 +1,5 @@
 import { EncodedSourceMap, TraceMap, originalPositionFor } from '@jridgewell/trace-mapping';
+// @ts-ignore
 import { TemplateNode } from 'svelte/types/compiler/interfaces';
 import { svelte2tsx, IExportedNames, internalHelpers } from 'svelte2tsx';
 import ts from 'typescript';
@@ -66,6 +67,7 @@ export interface DocumentSnapshot extends ts.IScriptSnapshot, DocumentMapper {
  * Options that apply to svelte files.
  */
 export interface SvelteSnapshotOptions {
+    parse: typeof import('svelte/compiler').parse | undefined;
     transformOnTemplateError: boolean;
     typingsNamespace: string;
 }
@@ -196,6 +198,7 @@ function preprocessSvelteFile(document: Document, options: SvelteSnapshotOptions
 
     try {
         const tsx = svelte2tsx(text, {
+            parse: options.parse,
             filename: document.getFilePath() ?? undefined,
             isTsFile: scriptKind === ts.ScriptKind.TS,
             mode: 'ts',

packages/language-server/src/plugins/typescript/features/CompletionProvider.ts

@@ -268,48 +268,63 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
         const fileUrl = pathToUrl(tsDoc.filePath);
         const isCompletionInTag = svelteIsInTag(svelteNode, originalOffset);
 
+        const completionItems: CompletionItem[] = eventAndSlotLetCompletions;
+        const isValidCompletion = createIsValidCompletion(document, position, !!tsDoc.parserError);
+        const addCompletion = (entry: ts.CompletionEntry, asStore: boolean) => {
+            if (isValidCompletion(entry)) {
+                let completion = this.toCompletionItem(
+                    tsDoc,
+                    entry,
+                    fileUrl,
+                    position,
+                    isCompletionInTag,
+                    addCommitCharacters,
+                    asStore,
+                    existingImports
+                );
+                if (completion) {
+                    completionItems.push(
+                        this.fixTextEditRange(
+                            wordRangeStartPosition,
+                            mapCompletionItemToOriginal(tsDoc, completion)
+                        )
+                    );
+                }
+            }
+        };
+
         // If completion is about a store which is not imported yet, do another
         // completion request at the beginning of the file to get all global
         // import completions and then filter them down to likely matches.
         if (word.charAt(0) === '$') {
             const storeName = word.substring(1);
             const text = '__sveltets_2_store_get(' + storeName;
             if (!tsDoc.getFullText().includes(text)) {
-                const storeImportCompletions =
-                    lang
-                        .getCompletionsAtPosition(
-                            filePath,
-                            0,
-                            {
-                                ...userPreferences,
-                                triggerCharacter: validTriggerCharacter
-                            },
-                            formatSettings
-                        )
-                        ?.entries.filter(
-                            (entry) => entry.source && entry.name.startsWith(storeName)
-                        ) || [];
-                completions.push(...storeImportCompletions);
+                const pos = (tsDoc.scriptInfo || tsDoc.moduleScriptInfo)?.endPos ?? {
+                    line: 0,
+                    character: 0
+                };
+                const virtualOffset = tsDoc.offsetAt(tsDoc.getGeneratedPosition(pos));
+                const storeCompletions = lang.getCompletionsAtPosition(
+                    filePath,
+                    virtualOffset,
+                    {
+                        ...userPreferences,
+                        triggerCharacter: validTriggerCharacter
+                    },
+                    formatSettings
+                );
+                for (const entry of storeCompletions?.entries || []) {
+                    if (entry.name.startsWith(storeName)) {
+                        addCompletion(entry, true);
+                    }
+                }
             }
         }
 
-        const completionItems = completions
-            .filter(isValidCompletion(document, position, !!tsDoc.parserError))
-            .map((comp) =>
-                this.toCompletionItem(
-                    tsDoc,
-                    comp,
-                    fileUrl,
-                    position,
-                    isCompletionInTag,
-                    addCommitCharacters,
-                    existingImports
-                )
-            )
-            .filter(isNotNullOrUndefined)
-            .map((comp) => mapCompletionItemToOriginal(tsDoc, comp))
-            .map((comp) => this.fixTextEditRange(wordRangeStartPosition, comp))
-            .concat(eventAndSlotLetCompletions);
+        for (const entry of completions) {
+            addCompletion(entry, false);
+        }
 
         // Add ./$types imports for SvelteKit since TypeScript is bad at it
         if (basename(filePath).startsWith('+')) {
@@ -455,14 +470,16 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
         position: Position,
         isCompletionInTag: boolean,
         addCommitCharacters: boolean,
+        asStore: boolean,
         existingImports: Set<string>
     ): AppCompletionItem<CompletionEntryWithIdentifier> | null {
         const completionLabelAndInsert = this.getCompletionLabelAndInsert(snapshot, comp);
         if (!completionLabelAndInsert) {
             return null;
         }
 
-        let { label, insertText, isSvelteComp, replacementSpan } = completionLabelAndInsert;
+        let { label, insertText, isSvelteComp, isRunesCompletion, replacementSpan } =
+            completionLabelAndInsert;
         // TS may suggest another Svelte component even if there already exists an import
         // with the same name, because under the hood every Svelte component is postfixed
         // with `__SvelteComponent`. In this case, filter out this completion by returning null.
@@ -477,6 +494,9 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
             label[label.length - 1] === '"'
         ) {
             label = label.slice(1, -1);
+        } else if (asStore) {
+            // only modify label, so that the data property is untouched, which is important so the resolving still works
+            label = `$${label}`;
         }
 
         const textEdit = replacementSpan
@@ -496,9 +516,9 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
             insertText,
             kind: scriptElementKindToCompletionItemKind(comp.kind),
             commitCharacters: addCommitCharacters ? this.commitCharacters : undefined,
-            // Make sure svelte component takes precedence
-            sortText: isSvelteComp ? '-1' : comp.sortText,
-            preselect: isSvelteComp ? true : comp.isRecommended,
+            // Make sure svelte component and runes take precedence
+            sortText: isRunesCompletion || isSvelteComp ? '-1' : comp.sortText,
+            preselect: isRunesCompletion || isSvelteComp ? true : comp.isRecommended,
             insertTextFormat: comp.isSnippet ? InsertTextFormat.Snippet : undefined,
             labelDetails,
             textEdit,
@@ -518,7 +538,9 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
         let { name, insertText, kindModifiers } = comp;
         const isScriptElement = comp.kind === ts.ScriptElementKind.scriptElement;
         const hasModifier = Boolean(comp.kindModifiers);
-        const isSvelteComp = isGeneratedSvelteComponentName(name);
+        const isRunesCompletion =
+            name === '$props' || name === '$state' || name === '$derived' || name === '$effect';
+        const isSvelteComp = !isRunesCompletion && isGeneratedSvelteComponentName(name);
         if (isSvelteComp) {
             name = changeSvelteComponentName(name);
 
@@ -533,14 +555,16 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
             return {
                 insertText: name,
                 label,
-                isSvelteComp
+                isSvelteComp,
+                isRunesCompletion
             };
         }
 
         if (comp.replacementSpan) {
             return {
                 label: name,
                 isSvelteComp,
+                isRunesCompletion,
                 insertText: insertText ? changeSvelteComponentName(insertText) : undefined,
                 replacementSpan: comp.replacementSpan
             };
@@ -549,7 +573,8 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
         return {
             label: name,
             insertText,
-            isSvelteComp
+            isSvelteComp,
+            isRunesCompletion
         };
     }
 
@@ -653,12 +678,12 @@ export class CompletionsProviderImpl implements CompletionsProvider<CompletionEn
 
         const detail = lang.getCompletionEntryDetails(
             filePath,
-            tsDoc.offsetAt(tsDoc.getGeneratedPosition(comp!.position)),
-            comp!.name,
+            tsDoc.offsetAt(tsDoc.getGeneratedPosition(comp.position)),
+            comp.name,
             formatCodeOptions,
-            comp!.source,
+            comp.source,
             errorPreventingUserPreferences,
-            comp!.data
+            comp.data
         );
 
         if (detail) {
@@ -913,7 +938,7 @@ const svelte2tsxTypes = new Set([
 
 const startsWithUppercase = /^[A-Z]/;
 
-function isValidCompletion(
+function createIsValidCompletion(
     document: Document,
     position: Position,
     hasParserError: boolean