Incorrect documentation on read_and_drop

[Thiez]

The documentation of the unstable function core::ptr::read_and_drop makes a reference to read_and_zero, but this function does not exist (anymore?). Expressing the semantics of read_and_drop in terms of something that does not exist is unhelpful.

The problem seems to be located here.

I imagine the fix would involve traveling back in time until before read_and_zero was removed and copying its documentation, after correcting for the differences between it and the read_and_drop function.

@steveklabnik

[bluss]

Filling drop is a temporary "feature" of rust, and in the long run this function will not be needed once the in-struct drop flags are gone. In anticipation of this improvement, it would be best to not write any code that relies on read_and_drop.

Edit: Well maybe that's exactly what to have in the docs..

[Thiez]

I'm not using that function, I was merely browsing the docs and noticed the documentation was wrong. I would expect the documentation of functions to be correct even if they are unstable and scheduled for removal, unless the removal is scheduled for the immediate future.