Re: [Boost-users] [move] non-inline move constructor - won't compile

Subject: Re: [Boost-users] [move] non-inline move constructor - won't compile
From: Krzysztof Czainski (1czajnik_at_[hidden])
Date: 2013-11-03 05:19:02

2013/11/2 Vicente J. Botet Escriba <vicente.botet_at_[hidden]>

> Le 02/11/13 12:02, Krzysztof Czainski a écrit :
>
>  Hi,
>>
>> I've been trying to writhe a non-inline move constructor, to place its'
>> implementation in a .cpp file. I'm having problems compiling my code, which
>> I managed to simplify (after examining output of the preprocessor) down to
>> this short code snippet:
>>
>> #include <boost/move/core.hpp>
>>
>> struct X
>> {
>>     X( ::boost::rv< X >& x );
>>     operator ::boost::rv<X>&() { return *static_cast< ::boost::rv<X>*
>> >(this); }
>> };
>>
>> X::X( ::boost::rv< X >& x ) {}
>>
>> Compiling a .cpp file with the above contents gives me:
>>
>> a.cpp:41:1: error: prototype for 'X::X(boost::rv<X>&)' does not match any
>> in class 'X'
>>  X::X( ::boost::rv< X >& x ) {}
>>  ^
>> a.cpp:35:8: error: candidates are: X::X(const X&)
>>  struct X
>>         ^
>> a.cpp:37:5: error: X::X(boost::rv<X>&)
>>      X( ::boost::rv< X >& x );
>>      ^
>>
>> I'm using MinGW gcc 4.8.1 in default -std mode (not-C++11 mode),
>> boost-1.54.
>>
> It works for me with clang-3.1 and clang-3.2, but not with gcc :( Really
> curious.
>
>
>> Am I doing something wrong here, or is it a bug in the compiler?
>>
>>  I would say that it is a bug on the compiler.
>
> Best,
> Vicente
>

Thanks for checking this out, Vincente.

I simplified it a bit more, found out, that it has to do with attribute
may_alias, and reported it to MinGW:
https://sourceforge.net/p/mingw/bugs/2126/

I also came up with a workaround, an example of which can be found in the
attached files.

Cheers,
Kris