Component re-renders indefinitely when changing state on render

[jayrobin]

• Check if updating to the latest Preact version resolves the issue

Describe the bug
When changing state on render Preact will re-render indefinitely rather than throwing a "Too many re-renders" error.

To Reproduce

codesandbox

import { render } from 'preact';
import { useState } from 'preact/hooks';

let rerenderCount = 0;
function App() {
  const [, setValue] = useState({});
  console.log('rendering', rerenderCount);
  rerenderCount++;

  if (rerenderCount < 50) {
    setValue({});
  }

  return (
    <div>Counter: {value}</div>
  );
}

render(<App />, window.root);

Expected behavior

Logs rendering 0 to rendering 24, then throws "Too many re-renders" error (similar to React - thrown here)

Actual behavior

Logs rendering 0 to rendering 49. If you remove the rerenderCount < 50 conditional, it will run indefinitely and crash the browser.

[rschristian]

When using preact/debug, which most Preact users will use in dev, #4349 addresses this.

React does seem to also detect infinite loops in prod too so I think we'll keep this open for the moment to better gauge whether we need a check/limit in preact/compat (or preact itself, I suppose)

Edit: Per Jovi, probably a bug. Whoops!

[JoviDeCroock]

We do already have a check in place that it doesn't infinitely render but I reckon that maybe it still pushes to the _component queue and hence can still loop https://github.com/preactjs/preact/blob/main/src/diff/index.js#L224

[JoviDeCroock]

This is fixed in latest with a preact/debug error throwing in development