Completion of options containing special characters is unreliable

[okdana]

You're supposed to be able to include special characters (+ and = are the only ones documented, but ideally you'd want also :, \, and [) in option names defined for completion by escaping them with a back-slash. This sort of works, but not really. Things get confused in the bowels of the completion system because the back-slashes aren't removed from the names before storing them. At the same time, many of the higher-level functions, like _arguments and _describe, handle characters like : and \ too naïvely.

I've submitted a patch, workers/43922, which fixes this well enough for the C stuff, but it either doesn't affect or subtly changes the higher-level behaviour. These are really weird edge cases that probably nobody will ever care about, but it would be nice to fix them if it's not too ridiculous.