[BUG] Not clean old classes on --watch rebuild

[PatrykKuniczak]

What version of Tailwind CSS are you using?

For example: v3.4.9

What build tool (or framework if it abstracts the build tool) are you using?

For example:
https://github.com/PatrykKuniczak/tw-reproduce/blob/main/package.json

What version of Node.js are you using?

For example: v20.11.1

What browser are you using?

For example: Chrome (Latest)

What operating system are you using?

For example: Windows 11

Reproduction URL

A Tailwind Play link or public GitHub repo that includes a minimal reproduction of the bug. Please do not link to your actual project, what we need instead is a minimal reproduction in a fresh project without any unnecessary code. This means it doesn't matter if your real project is private/confidential, since we want a link to a separate, isolated reproduction anyways.

Describe your issue

Run npm dev for reproduce, what's on video.

untitled.tailwind-output.css.2024-08-13.17-07-27.mp4

As you can see, --watch flag works well, but it leaves unnecessary old classes in output file.
I think it checks only, if class don't exists yet and create it, or even don't check nothing, overwrite file with brute force :)

I was used this classes, only once:

[thecrypticace]

Hi! This behavior is an intentional performance optimization for development. It makes it so that we don't have to:

• Rescan all files for every change (bad for memory and CPU); OR
• Keep track of which files every class appears in (bad for memory usage)

If you want the unused classes to be removed you can do a fresh build. Hope that helps!

[PatrykKuniczak]

@thecrypticace Yeah, i know i can do fresh build, but it seems strange.

Thanks for answer.