It's not. They're just using the term as a synonym for "rewrite". There's no documentation of any actual IP isolation in the linked article. They just want people to know it's new and not based on the existing LLVM or Linux runtimes.

This seems correct. Apologies for the unintentionally pedantic comment.

Speculating:

- The author wanted the personal challenge for the task

- The author wanted the code licensed under a BSD 2-clause and felt the existing license didn't fit her/his ideals.

> The original Clang/LLVM runtime is written in C++ with features that are not available in libc and in the NetBSD kernel

Yeah, I understand why they would write a clone, but "clean-room" has a specific meaning[1], and it's not clear why you would want or need that extra effort here.

Of course, I could just be misunderstanding, and they could be using "clean-room" as a synonym for "from scratch", rather than the meaning I linked to.

[1] https://en.wikipedia.org/wiki/Clean_room_design

Oh, right, I didn't even think about that meaning since we're not in the context of proprietary software. I'm 99.99% sure it's just "from scratch" here.

My reading is that they didn't look at the Linux implementation (as "clean-room").