bun.sh/test/regression/issue/25648.test.ts

import { expect, test } from "bun:test";
import { bunEnv, bunExe, tempDir } from "harness";

// https://github.com/oven-sh/bun/issues/25648
// Named function expression names should be renamed when they shadow an outer symbol
// that's referenced inside the function body. This prevents infinite recursion.

test("named function expression should be renamed when shadowing outer symbol", async () => {
  using dir = tempDir("issue-25648", {
    "lib.ts": `
export function get(x: number) {
  return x * 2;
}

export function doSomething(fn: () => number) {
  return fn();
}
`,
    "index.ts": `
import * as $ from './lib';

export function test() {
  return $.doSomething(function get() {
    return $.get(123);  // This should reference the outer get, not the function expression
  });
}

console.log(test());
`,
  });

  // Bundle and run the code
  await using buildProc = Bun.spawn({
    cmd: [bunExe(), "build", "index.ts", "--bundle", "--outfile=out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [buildStdout, buildStderr, buildExitCode] = await Promise.all([
    buildProc.stdout.text(),
    buildProc.stderr.text(),
    buildProc.exited,
  ]);

  expect(buildStderr).toBe("");
  expect(buildExitCode).toBe(0);

  // Run the bundled output
  await using runProc = Bun.spawn({
    cmd: [bunExe(), "out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [runStdout, runStderr, runExitCode] = await Promise.all([
    runProc.stdout.text(),
    runProc.stderr.text(),
    runProc.exited,
  ]);

  // Should print 246 (123 * 2), NOT cause infinite recursion
  expect(runStdout.trim()).toBe("246");
  expect(runStderr).toBe("");
  expect(runExitCode).toBe(0);
});

test("named function expression with namespace import should not cause infinite recursion", async () => {
  using dir = tempDir("issue-25648-2", {
    "svelte-mock.ts": `
export function get<T>(store: { value: T }): T {
  return store.value;
}

export function set<T>(store: { value: T }, value: T) {
  store.value = value;
}

export function bind_value(
  element: HTMLElement,
  get_fn: () => string,
  set_fn: (value: string) => void
) {
  return get_fn();
}
`,
    "index.ts": `
import * as $ from './svelte-mock';

const query = { value: "hello" };

// This pattern is generated by the Svelte compiler in dev mode
const result = $.bind_value(
  {} as HTMLElement,
  function get() {
    return $.get(query);  // Should call outer $.get, not this function
  },
  function set($$value: string) {
    $.set(query, $$value);
  }
);

console.log(result);
`,
  });

  // Bundle and run the code
  await using buildProc = Bun.spawn({
    cmd: [bunExe(), "build", "index.ts", "--bundle", "--outfile=out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [buildStdout, buildStderr, buildExitCode] = await Promise.all([
    buildProc.stdout.text(),
    buildProc.stderr.text(),
    buildProc.exited,
  ]);

  expect(buildStderr).toBe("");
  expect(buildExitCode).toBe(0);

  // Run the bundled output
  await using runProc = Bun.spawn({
    cmd: [bunExe(), "out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [runStdout, runStderr, runExitCode] = await Promise.all([
    runProc.stdout.text(),
    runProc.stderr.text(),
    runProc.exited,
  ]);

  // Should print "hello", NOT cause "Maximum call stack size exceeded"
  expect(runStdout.trim()).toBe("hello");
  expect(runStderr).toBe("");
  expect(runExitCode).toBe(0);
});

test("class expression name should be renamed when shadowing outer symbol", async () => {
  using dir = tempDir("issue-25648-3", {
    "lib.ts": `
export class Foo {
  value = 42;
}

export function makeThing<T>(cls: new () => T): T {
  return new cls();
}
`,
    "index.ts": `
import * as $ from './lib';

export function test() {
  return $.makeThing(class Foo extends $.Foo {
    getValue() {
      return this.value;
    }
    // Self-reference: uses the inner class name Foo
    static create() {
      return new Foo();
    }
    clone() {
      return new Foo();
    }
  });
}

const instance = test();
console.log(instance.getValue());
// Test self-referencing static method
console.log((instance.constructor as any).create().getValue());
// Test self-referencing instance method
console.log(instance.clone().getValue());
`,
  });

  // Bundle and run the code
  await using buildProc = Bun.spawn({
    cmd: [bunExe(), "build", "index.ts", "--bundle", "--outfile=out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [buildStdout, buildStderr, buildExitCode] = await Promise.all([
    buildProc.stdout.text(),
    buildProc.stderr.text(),
    buildProc.exited,
  ]);

  expect(buildStderr).toBe("");
  expect(buildExitCode).toBe(0);

  // Run the bundled output
  await using runProc = Bun.spawn({
    cmd: [bunExe(), "out.js"],
    env: bunEnv,
    cwd: String(dir),
    stdout: "pipe",
    stderr: "pipe",
  });

  const [runStdout, runStderr, runExitCode] = await Promise.all([
    runProc.stdout.text(),
    runProc.stderr.text(),
    runProc.exited,
  ]);

  // Should print 42 three times (getValue, static create().getValue, clone().getValue)
  expect(runStdout.trim()).toBe("42\n42\n42");
  expect(runStderr).toBe("");
  expect(runExitCode).toBe(0);
});