Declaration diagnostics allocate a diagnostic selector closure for every declaration visited #64720

// Ordinary files with many exported declarations, checked with `declaration: true` so that declaration
// diagnostics run the declaration transformer over every declaration.
import fs from "node:fs";
const FILES = 1500, CLASSES_PER_FILE = 6;
fs.mkdirSync("src", { recursive: true });
for (let f = 0; f < FILES; f++) {
  let text = "";
  for (let c = 0; c < CLASSES_PER_FILE; c++) {
    const n = `${f}_${c}`;
    text += `export interface Options${n} { name: string; size?: number; tags: readonly string[] }
export class Service${n}<T extends object = {}> {
    private readonly items = new Map<string, T>();
    static readonly kind = "service${n}" as const;
    constructor(public readonly options: Options${n}, protected limit = 10) {}
    get count() { return this.items.size; }
    set count(value: number) { this.limit = value; }
    add(key: string, item: T, overwrite = false) { if (overwrite || !this.items.has(key)) this.items.set(key, item); return this; }
    find(predicate: (item: T, key: string) => boolean) { for (const [key, item] of this.items) if (predicate(item, key)) return { key, item }; return undefined; }
    map<U>(fn: (item: T) => U) { return [...this.items.values()].map(fn); }
}
export function create${n}(options: Options${n}) { return new Service${n}(options); }
export const defaults${n} = { name: "${n}", size: ${c}, tags: ["a", "b"] as const };
export type Item${n} = ReturnType<typeof create${n}> extends Service${n}<infer T> ? T : never;
`;
  }
  fs.writeFileSync(`src/file${f}.ts`, text);
}
fs.writeFileSync("tsconfig.json", JSON.stringify({ compilerOptions: { target: "es2022", module: "esnext", moduleResolution: "bundler", strict: true, declaration: true, noEmit: true, types: [], lib: ["es2022"] }, include: ["src"] }));