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Andrew Clark
47ebc90b08
In the new reconciler, I made a change to how render phase updates work. (By render phase updates, I mean when a component updates another component during its render phase. Or when a class component updates itself during the render phase. It does not include when a hook updates its own component during the render phase. Those have their own semantics. So really I mean anything triggers the "`setState` in render" warning.) The old behavior is to give the update the same "thread" (expiration time) as whatever is currently rendering. So if you call `setState` on a component that happens later in the same render, it will flush during that render. Ideally, we want to remove the special case and treat them as if they came from an interleaved event. Regardless, this pattern is not officially supported. This behavior is only a fallback. The flag only exists until we can roll out the `setState` warnning, since existing code might accidentally rely on the current behavior.