I have a big wsdl file with many usage of xsd:attributeGroup. I know that is not supported. But have I any variants to generate Apex Classes from this wsdl?
I created a custom version of Wsdl2Apex that is a bit more flexible than the native Wsdl2Apex. You can get it via the FuseIT SFDC Explorer for free (Disclosure, this is via my current employer).
Where possible the version I created will try and ignore unsupported elements with the goal of generating at least some valid Apex. You might find some things don't work if they depended on those attributes, but you should be able to get a starting point.
Another alternative is the open source version of Wsdl2Apex. You could potentially modify that to work as you require.
At the moment I found only one way to parse my WSDL: It results in removing all attributeGroup tags and post their content all over the document where it needs by hand. Of course It was a little bit boring but this method really helps me to get so necessary for me classes in Apex.
Daniel, thanks a lot for your answer. Your tool looks well but it doesn't help me.(Some exceptions take place during parsing, that related to my WSLD document which I have no permission to share) I am sure that in some cases it really can help where standard SFDC WSDL parser will be forceless.