Re: delayed_forward: good, bad, ugly?

From: Gavin Lambert (boost_at_[hidden])
Date: 2023-01-09 22:13:23

On 10/01/2023 07:15, Peter Dimov wrote:
> If I understand correctly, the lack of strong guarantee is caused by the by-value
> constructor moving from the argument even when construction fails? E.g.
> 
>      Foo foo( true, std::move( my_t ) );
>      // leaves my_t moved-from on exception

If so, that doesn't seem like an unusual feature -- 
https://clang.llvm.org/extra/clang-tidy/checks/modernize/pass-by-value.html 
strongly encourages that constructors accept movable values by value, 
which will always move-from them even if the constructor later throws. 
(If the parameter type's move/copy constructor throws then it gets more 
complicated, though move constructors at least are typically expected to 
not throw.)