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If a function is known to freeze its inputs, and captures refs, then we can safely assume those refs are not mutated during render. An example is React Native's PanResponder, which is designed for use in interaction handling. Calling `PanResponder.create()` creates an object that shouldn't be interacted with at render time, so we can treat it as freezing its arguments, returning a frozen value, and not accessing any refs in the callbacks passed to it. ValidateNoRefAccessInRender is updated accordingly - if we see a Freeze <place> and ImmutableCapture <place> for the same place in the same instruction, we know that it's not being mutated. Note that this is a pretty targeted fix. One weakness is that we may not always emit a Freeze effect if a value is already frozen, which could cause this optimization not to kick in. The worst case there is that you'd just get a ref access in render error though, not miscompilation. And we could always choose to always emit Freeze effects, even for frozen values, just to retain the information for validations like this.
React Compiler
React Compiler is a compiler that optimizes React applications, ensuring that only the minimal parts of components and hooks will re-render when state changes. The compiler also validates that components and hooks follow the Rules of React.
More information about the design and architecture of the compiler are covered in the Design Goals.
More information about developing the compiler itself is covered in the Development Guide.