fix typescript types

Author: bengry

src/Popper.js

@@ -5,6 +5,7 @@ import {
   type Placement,
   type PositioningStrategy,
   type VirtualElement,
+  type StrictModifiers,
   type Modifier,
 } from '@popperjs/core/lib';
 import { ManagerReferenceNodeContext } from './Manager';
@@ -13,7 +14,7 @@ import { unwrapArray, setRef } from './utils';
 import { usePopper } from './usePopper';
 
 type ReferenceElement = ?(VirtualElement | HTMLElement);
-type Modifiers = Array<$Shape<Modifier<any>>>;
+type Modifiers = Array<StrictModifiers | $Shape<Modifier<string, {}>>>;
 
 export type PopperArrowProps = {|
   ref: Ref,

typings/react-popper.d.ts

@@ -1,5 +1,8 @@
-import * as React from 'react';
 import * as PopperJS from '@popperjs/core';
+import * as React from 'react';
+
+// Utility type
+type UnionWhere<U, M> = U extends M ? U : never;
 
 interface ManagerProps {
   children: React.ReactNode;
@@ -37,16 +40,30 @@ export interface PopperChildrenProps {
   arrowProps: PopperArrowProps;
 }
 
-export interface PopperProps {
+type StrictModifierNames = NonNullable<PopperJS.StrictModifiers['name']>;
+
+type StrictModifier<Name extends StrictModifierNames> = UnionWhere<
+  PopperJS.StrictModifiers,
+  { name?: Name }
+>;
+
+type Modifier<Name> = Name extends StrictModifierNames
+  ? StrictModifier<Name>
+  : Partial<PopperJS.Modifier<Name, object>>;
+
+export interface PopperProps<Modifiers> {
   children: (props: PopperChildrenProps) => React.ReactNode;
   innerRef?: React.Ref<any>;
-  modifiers?: Array<Partial<PopperJS.Modifier<any>>>;
+  modifiers?: ReadonlyArray<Modifier<Modifiers>>;
   placement?: PopperJS.Placement;
   strategy?: PopperJS.PositioningStrategy;
   referenceElement?: HTMLElement | PopperJS.VirtualElement;
   onFirstUpdate?: (state: Partial<PopperJS.State>) => void;
 }
-export class Popper extends React.Component<PopperProps, {}> {}
+export class Popper<Modifiers> extends React.Component<
+  PopperProps<Modifiers>,
+  {}
+> {}
 
 export function usePopper(
   referenceElement?: Element | null,