Rolldown PR #9305 sibling dynamic-entry side effect repro

Minimal repro for a behavior difference between Rollup and Rolldown PR #9305 (401218c).

Source graph

main.js
 ├─ import("./d1.js")
 └─ import("./d2.js")

d1.js
 ├─ static import main.js
 ├─ static import shared.js
 └─ import("./d2.js")

d2.js
 └─ static import shared.js

d1.js has a top-level side effect:

console.log('d1', marker);

Calling only main.load2() should not execute d1.js.

Outputs included

• dist/rollup-v4.60.3/ — generated with Rollup v4.60.3.
• dist/rolldown-pr9305/ — generated from Rolldown PR #9305 at 401218c.

Check

npm run check:rollup
# ["main","shared","d2"]

npm run check:rolldown
# ["main","shared","d1 main","d2"]

Problem

Rolldown PR #9305 emits this for d2.js:

import "./d1.js";
console.log("d2");

So import("./d2.js") executes sibling dynamic entry d1.js first, even though source semantics do not require d1.js to be loaded.

Rollup does not do this. Its d2.js imports shared.js directly:

import './shared.js';
console.log('d2');

The risky assumption appears to be treating “the same user entry can reach both d1 and d2” as “loading d2 implies d1 is already loaded”. Those are different: main.load2() can run before main.load1().

A safe dominator check needs to prove every dynamic-import path to d2 goes through d1, or avoid merging sibling dynamic entries this way.

Regenerate Rollup output

npm run build:rollup