Function findExportedSymbol

src/resolution/import-resolver.ts:2079–2110

* Find an exported symbol in `filePath`, following `export { x } from * './other'` and `export * from './other'` chains until the original * declaration is reached. Cycle-safe via the `visited` set. * * Without this, every barrel-style import (`import { Foo } from * './index'` where `index.ts`

(
  filePath: string,
  want: {
    isDefault: boolean;
    isNamespace: boolean;
    exportedName: string;
    memberName: string | null;
  },
  language: Language,
  context: ResolutionContext,
  visited: Set<string>,
  depth = 0
)

 * resolved file, not declarations the file forwarded.
 */
function findExportedSymbol(
  filePath: string,
  want: {
    isDefault: boolean;
    isNamespace: boolean;
    exportedName: string;
    memberName: string | null;
  },
  language: Language,
  context: ResolutionContext,
  visited: Set<string>,
  depth = 0
): Node | undefined {
  // Memoize fresh (top-level) lookups only: recursive re-export steps carry a
  // populated `visited` set, whose contents change the reachable answer.
  // Every ref to the same imported symbol repeats this exact walk, so the
  // top-level memo removes the re-export chase + per-file linear scans from
  // all but the first occurrence.
  if (depth === 0 && visited.size === 0) {
    let memo = exportedSymbolMemos.get(context);
    if (!memo) {
      memo = new Map();
      exportedSymbolMemos.set(context, memo);
    }
    const key = `${filePath}\0${want.isDefault ? 1 : 0}${want.isNamespace ? 1 : 0}\0${want.exportedName}\0${want.memberName ?? ''}\0${language}`;
    if (memo.has(key)) return memo.get(key);
    const result = findExportedSymbolWalk(filePath, want, language, context, visited, depth);
    memo.set(key, result);
    return result;
  }
  return findExportedSymbolWalk(filePath, want, language, context, visited, depth);
}

function findExportedSymbolWalk(
  filePath: string,