Typescript 错误 - “类型已声明但从未使用” in.ts。 在界面中使用时

Question

Why typescript give me error "'HttpRequest' is declared but never used." when HttpRequest was used in interface? How to fix this?

import fp from 'fastify-plugin'
import fastify from 'fastify'
import { IncomingMessage } from 'http'
import { Http2ServerRequest } from 'http2'

//'HttpRequest' is declared but never used.
type HttpRequest = IncomingMessage | Http2ServerRequest

declare module 'fastify' {
  interface FastifyRequest<
    HttpRequest,
    Query = fastify.DefaultQuery,
    Params = fastify.DefaultParams,
    Headers = fastify.DefaultHeaders,
    Body = any
  > {
    user: string
  }
}

function plugin(fastify, options, next) {
  fastify.decorateRequest('user', 'userData')
  next()
}

export const reqDecorator = fp(plugin)

Here is the FastifyRequest interface:

interface FastifyRequest<HttpRequest = IncomingMessage, Query = fastify.DefaultQuery, Params = fastify.DefaultParams, Headers = fastify.DefaultHeaders, Body = any>

Answer 1

You have not defined name for the type,

declare module 'fastify' {
  interface FastifyRequest<
    httpRequest = HttpRequest,

As IncomingMessage is used as type, again you need to give name for the type for FastifyRequest interface,

export interface FastifyRequest<httprequest = IncomingMessage, // added this
Query = fastify.DefaultQuery,
Params = fastify.DefaultParams,
Headers = fastify.DefaultHeaders,
Body = any> {
  // interface fields and methods
}