boost beast flat buffer move ctor, move assign and swap all "cancel" a prepare()

[paul.d.rose@…]

The boost beast flat_buffer "cancels" any outstanding prepare() when being moved from or swapped.

This seems like a very sane thing to do.

However, boost::asio::async_read_until depends on calling prepare() on it's DynamicBuffer and then calling the corresponding commit() on a moved-to version.

Flat buffer will (correctly) silently commit the minimum of the requested size and the size from the previous prepare(). When used with async_read_until, the commit is always zero, since the prepare was "cancelled" by the move.

The flat_buffer code always sets last_ to out_ during a move or swap, which is what achieves what I am calling the "cancel" of the prepare().

I tested setting last_ to other.last_ in the move ctor, move assignment, and swap, and verified that asio::async_read_until now works with beast::flat_buffer On this report I set component=asio, because I couldn't find beast on the drop box.

I'm working with 1.67 and g++ 7.30 on ubuntu 18.04

[anonymous]

Please consider this withdrawn.

The beast flat_buffer matches the asio::is_dynamic_buffer check due to the alignment of method signatures, but isn't intended to actually be an asio dynamic buffer.

"fixing" the move allowd the async_read_until to complete, but ( of course ) my buffer had been moved from, and my actual data was long gone.