typescript参数类型推断失败

  class Foo<P = { fn : (e: string)=> void }> extends React.Component<P>{}
  let foo = () => (
    <div>
      <Foo fn={e=> e}/> {/* e is any */}
    </div>
  )

P

// Do not change { __default?:true } to DefaultGenericParameter it only works with the former for some reason
type IfDefaultParameter<C, Default, NonDefault> = C extends { __default?:true } ? Default : NonDefault
type DefaultGenericParameter = { __default? : true; }

export type InferredProps<C extends React.ReactType> =
  C extends React.ComponentType<infer P> ? P :
  C extends keyof JSX.IntrinsicElements ? JSX.IntrinsicElements[C] :
  {};

// The props for Foo, will extract props from the generic parameter passed in 
type FooProps<T extends React.ReactType = React.ComponentClass<{ fn: (s: string )=> void }>> = InferredProps<T> & {
  other?: string
}

// Actual component class
class _Foo<P> extends React.Component<P>{}

// The public facing constructor 
const Foo : {
  new <P extends React.ReactType & {__default?: true} = React.ComponentClass<{ fn: (s: string )=> void }> & DefaultGenericParameter>(p: P) :
  IfDefaultParameter<P, _Foo<FooProps>, _Foo<FooProps<P>>>
} = _Foo as any;

  let foo = () => (
    <div>
      <Foo fn={e=> e}/> {/* e is string */}
      <Foo<React.ComponentClass<{ fn: (s: number )=> void }>> fn={e=> e}/> {/* e is number */}
    </div>
  )

Avatar

export type AvatarProps<C extends AnyComponent = AnyComponent> = StandardProps<
  PassthruProps<C, 'div'>,
  AvatarClassKey
> & {
  alt?: string;
  childrenClassName?: string;
  component?: C;
  imgProps?: React.HtmlHTMLAttributes<HTMLImageElement>;
  sizes?: string;
  src?: string;
  srcSet?: string;
};

type IfDefaultParameter<C, Default, NonDefault> = C extends { __default?:true } ? Default : NonDefault
type DefaultGenericParameter = { __default? : true; }

declare const Avatar : {
  new <C extends AnyComponent & DefaultGenericParameter = 'div' & DefaultGenericParameter>(props: C) 
  : IfDefaultParameter<C, React.Component<AvatarProps<'div'>>, React.Component<AvatarProps<C>>>
}

const AvatarTest = () => (
  <div>
    {/* e is React.MouseEvent<HTMLDivElement>*/}
    <Avatar onClick={e => log(e)} alt="Image Alt" src="example.jpg" />
    {/* e is {/* e is React.MouseEvent<HTMLButtonElement>*/}*/}
    <Avatar<'button'> onClick={e => log(e)} component="button" alt="Image Alt" src="example.jpg" />
    <Avatar<React.SFC<{ x: number }>>
      component={props => <div>{props.x}</div>} // props is props: {x: number;} & {children?: React.ReactNode;}
      x={3} // ok 
      // IS NOT allowed:
      // onClick={e => log(e)}
      alt="Image Alt"
      src="example.jpg"
    />
  </div>

declare function foo(params: { tag: 'a', bar(x: number): void }): void;
declare function foo(params: { tag: 'b', bar(x: boolean): void }): void;

foo({ tag: 'a', bar(x) { console.log('x =', x)} }); // (parameter) x: number

foo f

declare function foo<P>(params: { f: (p: P) => void } & P): void;

foo({
  f(params: { bar(x: number): void }) {},
  bar(x) {},
});

type ComposedProps<InnerProps, N extends string> = 
       InnerProps & { [n in N]: (props: InnerProps) => void };  

// Also I assume in reality it does not return `void` but `React.Element`,
//  but I don't think it matters

declare function foo<P>(params: P): void;

// foo generic parameter is given explicitly,
//  which allows to infer (and not repeat) parameter types for `f` and `bar` 
foo<ComposedProps<{bar(x: number): void}, 'f'>>({
  f(params) {}, // params: { bar(x: number): void; }
  bar(x) {}, // (parameter) x: number
});