xmlgen should ignore non-supported XML w/ a warning

[zeenix]

Creating a separate issue for the simpler/bug part of #255. As discussed there, we should ignore any unexpected XML with a warning on the standard error output, instead of just completely giving up.

[kb-1000]

As far as I've seen so far, the convention with XML usually tends to be silently ignoring elements and attributes from unknown namespaces, which are usually used for ignorable vendor/etc. extensions, see for example JAXB's XML schema binding extensions that no one other than JAXB needs or reads, or some of LibreOffice's OpenDocument extensions. A warning is probably not necessary or desirable, as long as the known elements and attributes are okay, an info/debug-level message controlled by a verbose mode would make more sense.

[zeenix]

A warning is probably not necessary or desirable

I disagree but that's not important. The important bit is to ignore unknown elements. Do you think you can contribute this?

[kira-bruneau]

It looks like this won't be straightforward to fix. quick-xml doesn't distinguish between namespaces when using serde deserialization: tafia/quick-xml#757, so zbus_xml will have to be refactored to use something like NsReader or xmlserde.

[zeenix]

It looks like this won't be straightforward to fix.

Yeah, definitely not. :(

quick-xml doesn't distinguish between namespaces when using serde deserialization: tafia/quick-xml#757,

More like tafia/quick-xml#218 .

so zbus_xml will have to be refactored to use something like NsReader or xmlserde

Yeah. Also xml crate might not be a bad idea to try. It's not serde and we'll need more manual deserialization code but you can't have it all I guess.

There is also the option of people needing this, to work on tafia/quick-xml#218 getting fixed. I know that's a tall order but at least there is already some WIP work on that done.