In w:Help:Link it states clearly that "in internal and interwiki link style, a plus sign in a page name is not allowed, the HTML and hence the rendered page just shows the wikitext, e.g. a+b".
However, looking at that page live on Wikipedia, the plus sign *is* shown in the link.
On my wiki (1.5.6) [[a+b]] is rendered as the wikitext.
I couldn't find any release notes that describes this change. Is it a Wikipedia customisation? Will upgrading MediaWiki give me this feature? Is it an actual feature, or just some crazy undocumented behaviour that I should steer clear of?
I've been using "CPlusPlus" when I mean "C++", but I'd love to change if someone can clear this up for me. I'll even update the documentation on Wikipedia out of gratitude :-)
cheers, Matt Curtis