Nikolaus Rath <Nikolaus@rath.org> writes:

> I just downloaded nnir.el from CVS and tried to run it with swish-e. I
> added
>
>  gnus-secondary-select-methods '((nnml ""
>                                        (nnml-directory "~/Gnus/Groups/")
>                                        (nnml-use-compressed-files t)
>                                        (nnir-search-engine swish-e)
>                                        (nnir-swish-e-index-files ("/home/nikratio/Gnus/swish-e/index.swish-e"))
>                                        (nnir-swish-e-remove-prefix "/home/nikratio/Gnus/swish-e/") )
>                                  (nnimap ""
>                                          (nnimap-server-address "xxxx")
>                                          (nnimap-stream starttls)
>                                          (nnir-search-engine imap)))
>
> to my configuration and created the index file. However, when I run G
> G in the Group Buffer, this results in
>
> Debugger entered--Lisp error: (wrong-type-argument arrayp nil)
>   aset(nil 0 228)
>   (mail-header-set-number novitem art)

I faintly remember that this was the reason I once resorted to
manually switching the global variables around instead of using server
variables to search with multiple engines.

It looks like an unlucky interaction between nnir-read-server-parm
falling back to global variables, and nnoo managing the global
variables when they're used inside select methods.

This seems to cause various errors depending on the combination of
engines and backends used, and the order of them in
gnus-opened-servers.

Does it work for you with nnir.el from CVS plus the following patch
and nnir-mail-backend set to nil (it isn't by default)?