Add Svelte indexing support

Transform Svelte components with svelte2tsx while mapping symbols and ranges back to the original source.

Cover runes, legacy and JavaScript components, imported stores, malformed files, modern module resolution, and cross-project prop identity.

Amp-Thread-ID: https://ampcode.com/threads/T-01a029e2-5095-710a-9cce-0c6d8645c173

Author: eseliger

README.md

@@ -1,6 +1,7 @@
 # scip-typescript
 
-[SCIP](https://github.com/sourcegraph/scip) indexer for TypeScript and JavaScript.
+[SCIP](https://github.com/sourcegraph/scip) indexer for TypeScript, JavaScript,
+and Svelte.
 
 ## Quick start
 
@@ -33,6 +34,18 @@ scip-typescript index --infer-tsconfig
 To improve the quality of indexing results for JavaScript,
 consider adding `@types/*` packages as `devDependencies` in `package.json`.
 
+### Indexing a Svelte project
+
+Install the project dependencies and run the indexer from the directory that
+contains the project's `tsconfig.json` or `jsconfig.json`. SvelteKit projects
+should run `svelte-kit sync` first so their generated configuration is current.
+
+```sh
+npm install # or yarn/pnpm install
+npx svelte-kit sync # SvelteKit projects only
+scip-typescript index
+```
+
 ### Index a TypeScript project using Yarn workspaces
 
 Navigate to the project root, containing `package.json`.

package.json

@@ -1,7 +1,7 @@
 {
   "name": "@sourcegraph/scip-typescript",
   "version": "0.4.0",
-  "description": "SCIP indexer for TypeScript and JavaScript",
+  "description": "SCIP indexer for TypeScript, JavaScript, and Svelte",
   "publisher": "sourcegraph",
   "bin": "dist/src/main.js",
   "main": "./dist/src/main.js",
@@ -36,9 +36,12 @@
   },
   "homepage": "https://github.com/sourcegraph/scip-typescript#readme",
   "dependencies": {
+    "@jridgewell/trace-mapping": "^0.3.31",
     "commander": "^14.0.3",
     "google-protobuf": "^4.0.2",
     "progress": "^2.0.3",
+    "svelte": "^5.56.10",
+    "svelte2tsx": "^0.7.61",
     "typescript": "^6.0.3"
   },
   "devDependencies": {

snapshots/input/multi-project/packages/a/src/Component.svelte

@@ -0,0 +1,6 @@
+<script lang="ts">
+  type Props = { label: string }
+  let { label }: Props = $props()
+</script>
+
+<p>{label}</p>

snapshots/input/multi-project/packages/b/src/App.svelte

@@ -0,0 +1,5 @@
+<script lang="ts">
+  import Component from '../../a/src/Component.svelte'
+</script>
+
+<Component label="cross-project" />

snapshots/input/svelte/Child.svelte

@@ -0,0 +1,6 @@
+<script lang="ts">
+  let { label, count = 0 }: { label: string; count?: number } = $props()
+  const doubled = $derived(count * 2)
+</script>
+
+<button>{label}: {doubled}</button>

snapshots/input/svelte/Generic.svelte

@@ -0,0 +1,5 @@
+<script lang="ts" generics="Value">
+  let { value }: { value: Value } = $props()
+</script>
+
+<span>{value}</span>

snapshots/input/svelte/Legacy.svelte

@@ -0,0 +1,5 @@
+<script lang="ts">
+  export let value: string
+</script>
+
+<span>{value}</span>

snapshots/input/svelte/Parent.svelte

@@ -0,0 +1,31 @@
+<script lang="ts">
+  import { writable } from 'svelte/store'
+  import Child from './Child.svelte'
+  import Generic from './Generic.svelte'
+  import Legacy from './Legacy.svelte'
+  import Plain from './Plain.svelte'
+  import { format, type User } from './helper'
+  import { importedCount } from './stores'
+
+  const user: User = { name: 'Ada' }
+  let clicks = $state(1)
+  const count = writable(2)
+  let generic: Generic<User> | undefined = $state()
+
+  function increment(): void {
+    clicks += 1
+  }
+</script>
+
+{#snippet greeting(name: string)}
+  <strong>Hello {name}</strong>
+{/snippet}
+
+<button onclick={increment}>Increment</button>
+<Child label={format(user.name)} count={clicks} />
+<Generic bind:this={generic} value={user} />
+<Legacy value="legacy" />
+<Plain enabled={true} />
+<p>{$count}</p>
+<p>{$importedCount}</p>
+{@render greeting(user.name)}

snapshots/input/svelte/Plain.svelte

@@ -0,0 +1,7 @@
+<script>
+  export let enabled = false
+</script>
+
+{#if enabled}
+  <p>enabled</p>
+{/if}

snapshots/input/svelte/helper.ts

@@ -0,0 +1,7 @@
+export interface User {
+  name: string
+}
+
+export function format(name: string): string {
+  return name.toUpperCase()
+}