imports generated by rollupConfig.treeshake = false may create unusable output (for rollup itself).

[07akioni]

• Rollup Version: 2.34.1
• Operating System (or Browser): Mac
• Node Version (if applicable): v12.16.1
• Link to reproduction (IMPORTANT, read below):

https://repl.it/join/wpkwnjbg-07akioni

https://github.com/07akioni/rollup-bug

Expected Behavior

it outputs { a: 'a', b: [ 'b', 'a' ] }

Actual Behavior

it outputs # { a: 'a', b: undefined }

The bundled app is

var a = 'a';

var ab = /*#__PURE__*/Object.freeze({
	__proto__: null,
	a: a,
	b: b
});

var b = ['b', a];

console.log({ ...ab });

var preset = 'wow';

console.log(preset);

However var b = ['b', a]; should come before var ab = ...

It is result from

// package/b/b.js (generated by rollup with no tree-shaking)

import a from '../a/a.js';
import '../ab.js'; // <------------ The import stmt cause the problem

var b = ['b', a];

export default b;

[lukastaegert]

It appears this one was fixed in #3840