[Enhancement][Treeshaking]: treeshake the new Class

[SoonIter]

What problem does this feature solve?

// index.js
import { b } from './qux.js'
console.log(b)

// ./qux.js
class A {}
export const a = new A();
export const b = 1;

expected output

aligned with rollup

const b = 1;

console.log(b);

actual output

class A {
}
new A();
const b = 1;
console.log(b);

What does the proposed API look like?

https://rollupjs.org/repl/?version=4.28.1&shareable=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

https://github.com/SoonIter/rslib-treeshaking-new-class

[SoonIter]

😄 I do not know why rollup treeshakes this case, this case is very common for treeshaking invalidation, literally speaking, new Class() has sideEffect

[fi3ework]

It could be tree-shaked if no side-effect performed in new, just like in this case. But Rollup seems not considering at all as of now https://rollupjs.org/repl/?version=4.28.1&shareable=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

[SoonIter]

It could be tree-shaked if no side-effect performed in new, just like in this case. But Rollup seems not considering at all as of now

Your case is wrong, i fixed it 😂

https://rollupjs.org/repl/?version=4.28.1&shareable=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

[SoonIter]

It could be tree-shaked if no side-effect performed in new, just like in this case. But Rollup seems not considering at all as of now

Your case is wrong, i fixed it 😂

I can ensure that it is a rollup "feature" by this behavior...

real world normal cases

https://rollupjs.org/repl/?version=4.28.1&shareable=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

https://rollupjs.org/repl/?version=4.28.1&shareable=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