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Subject: Re: [boost] [variant] Heads-up!
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2019-04-29 17:44:08


On 4/29/19 11:30 AM, Antony Polukhin via Boost wrote:
> I've merged a very cool optimization by Nikita Kniazev into the master
> branch. From now on boost::variant does pointer stealing for recursive
> variants.
> This significantly improves the performance of the variants move constructors.
> However if you use a variant variable after the std::move for anything
> except destruction and assignment then you're getting an UB. Beware!

boost::variant goes to great lengths to prevent
exactly this situation. You just broke it. This
change is unacceptable. Please revert it. This
optimization can be used iff. you have a way to
construct a valid object in the rhs.

In Christ,
Steven Watanabe

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