Re: RFC: lalr1.cc: support move semantics

[Hans Åberg]

> On 12 Sep 2018, at 23:46, Frank Heckenbach <address@hidden> wrote:
> 
> Hans Åberg wrote:
> 
>>>>>  Modern C++ (i.e., C++11 and later) introduced "move only" types: types 
>>>>> such
>>>>>  as std::unique_ptr<T> that can never be duplicated.  They must never be
>>>>>  copied (by assignments and constructors), they must be "moved".  The
>>>>>  implementation of lalr1.cc used to copy symbols (including their semantic
>>>>>  values).  This commit ensures that values are only moved in modern C++, 
>>>>> yet
>>>>>  remain compatible with C++98/C++03.
>>>> 
>>>> Hopefully copy only types can still be used. So say:
>>> 
>>> C++ will automatically copy when copy is available and move is not.
>> 
>> Yes, but strictly, that is not what the above text says.
> 
> Depends on your definitions. IMHO in (modern) C++ "move" always
> implies "copy" if possible and necessary,

But that does not mean that a move operator is a copy operators, only that 
another is used.

> though I wouldn't object
> to spelling it out here.

It is written in a pedagogical style intended for those that may not know. For 
those that do know, it suffices:

This commit introduces C++11 move operators, while retaining the behavior under 
C++98/C++03.