ant-design/components/form/hooks/useFormWarning.ts

import { useEffect } from 'react';
import warning from '../../_util/warning';
import type { FormProps } from '../Form';

const names: Record<string, number> = {};

export default function useFormWarning({ name }: FormProps) {
  useEffect(() => {
    if (name) {
      names[name] = (names[name] || 0) + 1;

      warning(names[name] <= 1, 'Form', 'There exist multiple Form with same `name`.');

      return () => {
        names[name] -= 1;
      };
    }
  }, [name]);
}