Workaround for type recursion with array fields

[sohrab-]

I have seen some Github issues (open and closed) about problems with type recursion and some improvements that may come in v8. I have a use case where it has only one level of recursion but it is causing significant performance issues. I am wondering if anyone has any suggestions to work around this until v8 comes out.

Here is a minimal repo: https://stackblitz.com/edit/vitejs-vite-b8aq7akf?file=src%2FForm.tsx

You can run the following to see the hotspots:

tsc -b --generateTrace ./trace
npx analyze-trace ./trace

This is what I got:

Hot Spots
└─ Check file /home/projects/vitejs-vite-b8aq7akf/src/Form.tsx (1140ms)
   └─ Check deferred node from (line 26, char 5) to (line 28, char 20) (714ms)
      └─ Determine variance of type 19189 (652ms)
         └─ {"id":19189,"kind":"GenericTypeAlias","name":"UseFormResetField","aliasTypeArguments":[19190],"location":{"path":"/home/projects/vitejs-vite-b8aq7akf/node_modules/react-hook-form/dist/types/form.d.ts","line":507,"char":1}}
            └─ {"id":19190,"kind":"TypeParameter","name":"TFieldValues","location":{"path":"/home/projects/vitejs-vite-b8aq7akf/node_modules/react-hook-form/dist/types/form.d.ts","line":507,"char":31}}

In my real repo, it detects hotspots of 7+ seconds 🫠 and it flags usages of useFieldArray() and useWatch() on this nested field. In the real repo, I also get Type instantiation is excessively deep and possibly infinite. when I try to do setValue() on the that field.

This all surprises me coz the form schema type is not even infinitely recursive (only 1 level).

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My workaround with similar cases in the past was to entirely move the type out RHF and replace it with unknown, and then cast on access (ugly, I know). This is less an option with the above ☝️ case, if you still want to use things like useFieldArray().