[React 19] Support React Compiler with older React versions for libraries

[devongovett]

[React 19] Support React Compiler with older React versions for libraries

[josephsavona]

Thanks for filing this. We absolutely want to make the compiler work with older versions of React as well. It is possible to polyfill the memo cache function today on older versions of React: there are preliminary docs for this in the working group.

Note that there are a bunch of things for us to figure out here. Over time we will likely add additional new internal runtime APIs for the compiler to call, and we are working on the strategy for making that work while still allowing the compiler to work across versions.

But to experiment with the compiler, feel free to use the polyfill option. However, note that we strongly recommend using strict mode to help identify potential problems in your code.