TypeScript版本： 3.6.3
搜索词： TypedPropertyDescriptor, MethodDecorator, TS2345, 属性'value'的类型不兼容。
代码

type MyDynamicDescriptor = <T>(input: T) => T
type MyStaticDescriptor = (input: number) => number
function dynamicDecorator(foo: string) {
  return (_: any, __: any, descriptor: TypedPropertyDescriptor<MyDynamicDescriptor>) => {
    console.log('foo:', foo)
    console.log('descriptor.value:', descriptor.value)
  }
}
function staticDecorator(foo: string) {
  return (_: any, __: any, descriptor: TypedPropertyDescriptor<MyStaticDescriptor>) => {
    console.log('foo:', foo)
    console.log('descriptor.value:', descriptor.value)
  }
}
class myClass {
  @dynamicDecorator('bar')
  myMethod(input: number): number {
    return input + 42
  }
  @staticDecorator('bar')
  myOtherMethod(input: number): number {
    return input + 42
  }
}

预期行为：

dynamicDecorator 和 staticDecorator 都没有编译错误。

实际行为：

dynamicDecorator 有编译错误：

error TS2345: Argument of type 'TypedPropertyDescriptor<(input: number) => Promise<number>>' is not assignable to parameter of type 'TypedPropertyDescriptor<MyDynamicDescriptor>'.
  Types of property 'value' are incompatible.
    Type '((input: number) => Promise<number>) | undefined' is not assignable to type 'MyDynamicDescriptor | undefined'.
      Type '(input: number) => Promise<number>' is not assignable to type 'MyDynamicDescriptor'.

** playground链接**