request.url is incorrect and inconsistent when NextResponse.rewrite() is used

[colinclerk]

Verify canary release

• [X] I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 21.6.0: Mon Aug 22 20:17:10 PDT 2022; root:xnu-8020.140.49~2/RELEASE_X86_64
Binaries:
  Node: 16.13.1
  npm: 8.19.1
  Yarn: 1.22.17
  pnpm: N/A
Relevant packages:
  next: 12.3.1-canary.3
  eslint-config-next: 12.3.0
  react: 18.2.0
  react-dom: 18.2.0

What browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

next dev, Vercel

Describe the Bug

When NextResponse.rewrite(newUrl) is called, we expect the value of newUrl to consistently be reflected inside request.url for the new URL's handler.

Instead, the value of request.url is inconsistent depending on the environment (dev vs prod) and the runtime (node vs edge).

The table below details the current behavior:

Development		Production
Edge ✅	Node ❌	Edge ❌	Node ❌
request.url is set to the new URL passed to rewrite()	request.url is set to the original URL	request.url is set to the pathname of the original URL and the query string of the new URL passed to rewrite()

Note: this table holds for both API routes and React pages

Expected Behavior

We haven't found any documentation of the intended behavior.

We would expect request.url in the endpoint to always reflect the URL passed to rewrite. If not, it feels like it hasn't been rewritten.

Link to reproduction

https://github.com/clerkinc/nextjs-middleware-debugging

To Reproduce

The readme in the linked repository includes commands to quickly reproduce every scenario

The steps to rebuild the repo are:

1. Build and host endpoints for each permutation (dev and prod, node and edge). In each endpoint, log the value of request.url
2. Build middleware to rewrite a request to that endpoint. When you rewrite, make sure to include a query param since they are part of what behaves inconsistently.
3. run a request that triggers your middleware rewrite, then check what the logs to see what request.url was set to