let resolvedAs = as   <-- "/posts/[pid]?pid=1234&foo=bar"

    if (process.env.__NEXT_HAS_REWRITES) {
      // this code is only run in dev
      // here dev will set resolvedAs  to "/posts/[pid]"
      resolvedAs = resolveRewrites(
        parseRelativeUrl(as).pathname, <------------------ "/posts/[pid]"
        pages,
        basePath,
        rewrites,
        query,
        (p: string) => this._resolveHref({ pathname: p }, pages).pathname!
      )

      if (resolvedAs !== as) {
        const potentialHref = removePathTrailingSlash(
          this._resolveHref(
            Object.assign({}, parsed, { pathname: resolvedAs }),
            pages,
            false
          ).pathname!
        )

        // if this directly matches a page we need to update the href to
        // allow the correct page chunk to be loaded
        if (pages.includes(potentialHref)) {
          route = potentialHref
          pathname = potentialHref
          parsed.pathname = pathname
          url = formatWithValidation(parsed)
        }
      }
    }
    // in dev resolvedAs = "/posts/[pid]" & and in prod resolvedAs = "/posts/[pid]?pid=1234&foo=bar"
    resolvedAs = delLocale(delBasePath(resolvedAs), this.locale)

export default function resolveRewrites(
  asPath: string,
  pages: string[],
  basePath: string,
  rewrites: Rewrite[],
  query: ParsedUrlQuery,
  resolveHref: (path: string) => string
) {
  if (!pages.includes(asPath)) { <------------------- this is false
    // ....
  }
  return asPath <---------- // returns /posts/[pid]
}