[next/link] Using URL object with dynamic routes does not work

Bug report

Describe the bug

The documentation for next/link describes using an URL object for the href prop: https://nextjs.org/docs/api-reference/next/link#with-url-object

However, it seems that for dynamic routes, the value of the slug key from the query object just gets appended to the URL as a normal query parameter and the link ends up pointing to: /blog/[slug]?slug=my-post

This happens in both dev and production builds.

To Reproduce

1. Go to https://github.com/mantysalo/next-link-issue
2. Clone the repo
3. Start dev server
4. Observe the URL of the link
5. See error

Expected behavior

With an URL object as such:

{
          pathname: '/blog/[slug]',
          query: { slug: 'my-post' },
}

I would expect the url to be: /blog/my-post as it is stated in the documentation.

System information

• OS: macOS
• Version of Next.js: 9.5.3
• Version of Node.js: 12.16.0

[lfades]

@pixelass This shouldn’t be an issue anymore, make sure to be on the latest Next.js version, and if there is a bug then please open a new issue with a reproduction 🙏

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.