properly define what "canonical" means in `os.path.realpath`

Documentation

The documentation says:
https://github.com/python/cpython/blob/2fd09b011031f3c00c342b44e02e2817010e507c/Doc/library/os.path.rst?plain=1#L406-L409

So it merely mentions symlink resolution, but not what else it means (if anything).

It does however mention that whatever it does is OS dependent:
https://github.com/python/cpython/blob/2fd09b011031f3c00c342b44e02e2817010e507c/Doc/library/os.path.rst?plain=1#L416-L418

IMO, it should be clearly documented what it does or at least:

• what it guarantees to the least (For example will the pathname be absolute? Will it be normalised?)
  and/or:
• which OS function it’s identical to, like on POSIX where that would probably realpath(), and whether there are differences to that

Especially since IMO "canonical" pathname (though I think it has no formal definition, or is there anything in POSIX?) means rather just that there are no symlinks left, i.e. that the file is "reached" by its true (=canonical) name.

But that could still be a relative pathname, and perhaps even one that is not normalised.

Cheers,
Chris.

Linked PRs

• gh-134755

Bắt đầu trong Doc/library/os.path.rst tại các dòng được trích dẫn 406-409 và 416-418, sau đó so sánh với tài liệu tham chiếu POSIX về realpath() được liên kết trong issue. Ghi lại các bảo đảm tối thiểu của os.path.realpath và mọi hành vi hoặc khác biệt dành riêng cho hệ điều hành, với cách diễn đạt làm rõ “canonical” có nghĩa là gì.