# react-hooks/incompatible-library

> Report calls to library APIs that the React Compiler cannot memoize safely

The React Compiler reuses a value from the last render as long as its inputs are the same. A few libraries return objects and functions that stay the same while the data behind them changes. If they were memoized, they'd show stale data, so the compiler leaves every component and hook that calls one of them unoptimized. This rule tells you where that happens.

| Package | What is reported |
| --- | --- |
| `react-hook-form` | A call to the `watch()` that `useForm()` returns |
| `@tanstack/react-table` | `useReactTable()` |
| `@tanstack/react-virtual` | `useVirtualizer()` |

{/* Generated by src/codegen/lint-rule-docs.ts. Do not edit this section. */}

## Configure

Off by default. To turn it on:

```toml bunfig.toml
[lint.rules]
"react-hooks/incompatible-library" = "error" # or "warn"
```

{/* End of the generated section. */}

## Examples

Reported:

{/* bad */}
```jsx
import { useForm } from "react-hook-form";

function Signup() {
  const { register, watch } = useForm();
  const email = watch("email");
  return <input {...register("email")} title={email} />;
}
```

{/* bad {"count": 2} */}
```jsx
import { useReactTable } from "@tanstack/react-table";
import { useVirtualizer } from "@tanstack/react-virtual";

function Table({ columns, data }) {
  const table = useReactTable({ columns, data });
  return <div>{table.getRowModel().rows.length} rows</div>;
}

function List({ rows, estimateSize }) {
  const virtualizer = useVirtualizer({ count: rows.length, estimateSize });
  return <div style={{ height: virtualizer.getTotalSize() }} />;
}
```

Not reported:

{/* good */}
```jsx
import { useForm, useWatch } from "react-hook-form";

function Signup() {
  const { register, control } = useForm();
  const email = useWatch({ control, name: "email" });
  return <input {...register("email")} title={email} />;
}
```

## When not to use it

If you don't build with the React Compiler, nothing is memoized for you and these APIs work as usual.