bug#44874: 27.1; nXML: error when setting the xhtml5.rnc schema

[Vincent Lefevre]

On 2020-11-26 11:43:17 +0100, Lars Ingebrigtsen wrote:
> Here's what I did:
> 
> cd /tmp
> git clone https://github.com/emacsmirror/html5-schema
> emacs -Q foo.xml
> M-x rng-set-schema-file RET /tmp/html5-schema/xhtml5.rnc RET
> 
> It asks me whether to save the location, and I answer "y", and I get no
> error.

OK, there seems to be a difference when doing that instead of using
the menu. BTW, after saving the location, if you quit and reopen
the file, you should now get the error message.

> Do you have a more precise recipe for reproducing the error?

If you don't get the error message, just make sure to validate
with "C-c C-v". This is what makes the error appear.

Note: After that, if I select Set Schema → Any Well-Formed XML
from the menu, I get "Using vacuous schema", which is fine.
But C-c C-v still gives the error "Incorrect schema. Unknown
datatype library http://whattf.org/datatype-draft";!

This is with Debian's GNU Emacs 27.1.

Note: it is possible to reproduce the issue from an empty XML file,
but after the schema is selected, one needs to type the beginning of
an element, e.g. "<r". Otherwise nXML knows that the file is invalid
without using the schema.

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)