Re: [boost] [move] unique_ptr: problems with move-assign constructor when used with base/derived classes in C++03

Subject: Re: [boost] [move] unique_ptr: problems with move-assign constructor when used with base/derived classes in C++03
From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2015-03-06 11:46:12

El 05/03/2015 a las 12:17, Adam Romanek escribió:
> Hi,
>
> There is a problem with move-assignment constructor in
> boost::movelib::unique_ptr when used with a pair of base/derived classes
> in C++98/03 mode [1] (uncomment the code to see the compiler error).
>
> Is it a known issue? Or a limitation of the emulation?

It's a limitation because the c++03 standard requires a viable copy 
constructor for copy initialization expressions:

T t = T()

and unique_ptr has no copy constructor.

Some non-conforming compilers (like MSVC 7.1) don't require it, but the 
standard is clear. You can use use direct initialization to get the same 
effect:

unique_ptr<Base> z(boost::move(x));

Best,

Ion