Rollup deletes code with side effects due to incorrect pure annotations

[evanw]

Rollup Version

2.60.1

Operating System (or Browser)

Chrome 96

Node Version (if applicable)

No response

Link To Reproduction

https://rollupjs.org/repl/?version=2.60.1&shareable=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

Expected Behaviour

Here's the input code from the link above:

const x = new Map({
  [Symbol.iterator]() {
    return {
      next() {
        console.log('side effect')
        return { done: true }
      }
    }
  }
})

The code generated by Rollup should print side effect.

Actual Behaviour

The code generated by Rollup is incorrectly empty, and so prints nothing.

The context for this is that someone wanted esbuild to do what Rollup does here: evanw/esbuild#1791. However, what Rollup does here seems to be incorrect, so I reported a bug here instead. I don't need this to be fixed myself so feel free to do what you want with this bug report.

[rollup-bot]

This issue has been resolved via #4955 as part of rollup@3.21.2. You can test it via npm install rollup.