Preserve TypeScript import symbol output

Limit direct import-alias resolution to generated Svelte sources and imports from .svelte modules so ordinary TypeScript indexes remain byte-for-byte unchanged.

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

Author: eseliger

src/FileIndexer.ts

@@ -575,7 +575,11 @@ export class FileIndexer {
       const alias = node.name
         ? this.checker.getSymbolAtLocation(node.name)
         : undefined
-      if (alias && (alias.flags & ts.SymbolFlags.Alias) !== 0) {
+      if (
+        (sourceInfo?.isSvelte || isSvelteImport(node)) &&
+        alias &&
+        (alias.flags & ts.SymbolFlags.Alias) !== 0
+      ) {
         const imported = this.checker.getAliasedSymbol(alias)
         for (const declaration of imported.declarations || []) {
           return this.scipSymbol(declaration)
@@ -853,6 +857,20 @@ function isAnonymousContainerOfSymbols(node: ts.Node): boolean {
   )
 }
 
+function isSvelteImport(
+  node: ts.ImportSpecifier | ts.ImportClause | ts.NamespaceImport
+): boolean {
+  let parent: ts.Node | undefined = node.parent
+  while (parent && !ts.isImportDeclaration(parent)) {
+    parent = parent.parent
+  }
+  return (
+    !!parent &&
+    ts.isStringLiteral(parent.moduleSpecifier) &&
+    parent.moduleSpecifier.text.endsWith('.svelte')
+  )
+}
+
 function scriptElementKind(
   node: ts.Node,
   sym: ts.Symbol