>>>>> In <b9y6532g2am.fsf@jpl.org> Katsumi Yamaoka wrote:

> I noticed I cannot delete nnml groups if there are persistent
> articles.

> Debugger entered--Lisp error: (file-error "Removing old name:
>  is a directory" "/home/yamaoka/News/cache/nnml:foo.bar.baz")
>   delete-file("/home/yamaoka/News/cache/nnml:foo.bar.baz")
>   gnus-delete-file("/home/yamaoka/News/cache/nnml:foo.bar.baz")
>   gnus-cache-delete-group("nnml:foo.bar.baz")
>   gnus-request-delete-group("nnml:foo.bar.baz" (4))
>   gnus-group-delete-group("nnml:foo.bar.baz" (4))
>   call-interactively(gnus-group-delete-group)

[...]

> Emacs 21 provides the `dired-delete-file' function which deletes
> a file and also a directory recursively.  Can't we use the copy
> of it as `gnus-delete-file'?

Oops, that's dangerous!  It may delete articles in lower
hierarchical groups.  Instead, I made a new function as shown
below and committed it.