[Next 9.5.4+] Router.push duplicates query params in production mode, but not in dev mode

Bug report

Describe the bug

I recently came across this bug while using the “new” router.push method. Using the following

router.push({
    pathname: '/posts/[pid]',
    query: {
        pid: '1234',
        foo: 'bar'
    }
})

In dev, this directs me to /posts/1234?foo=bar

In prod, this directs me to /posts/1234?pid=1234&foo=bar

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

1. clone and install this repo
2. run yarn build
3. run yarn start
4. navigate to localhost:3000
5. press The Button

Expected behavior

I would have expected production to run the same as in dev mode. Like I said above, pushing with this information

{
    pathname: '/posts/[pid]',
    query: {
        pid: '1234',
        foo: 'bar'
    }
}

Should send me to /posts/1234?foo=bar.

System information

• OS: macOS
• Browser (if applies): chrome
• Version of Next.js: 9.5.4, 9.5.5
• Version of Node.js: 12.16.1

[vitosamson]

I think I’m seeing this or a similar bug as well. I’ve created a minimal reproduction here: https://github.com/vitosamson/next-router-bug-repro. Spin it up (yarn dev), navigate to /[id] and then update the route via the Foo/Bar buttons.

For a route like /[id], pushing a new route via router.push({ pathname: '/[id]', query: { id: 'foo' } }) will cause router.asPath to become /[id]?id=foo instead of /foo.

This is causing issues for me when trying to update the route’s search programatically (I’m not sure if there’s another way I’m supposed to be doing that other than the query object?). I’ve had to resort to using router.asPath for the initial SSR and then ${window.location.pathname}${window.location.search} thereafter when I need to know what the current full path is.

If this is fixed via #18009, any idea when a new version will be cut with that?

[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.