Re: [boost] [operators] The future of Boost.Operators

Subject: Re: [boost] [operators] The future of Boost.Operators
From: Jeffrey Lee Hellrung, Jr. (jeffrey.hellrung_at_[hidden])
Date: 2013-04-25 14:40:13

On Thu, Apr 25, 2013 at 11:03 AM, Marc Glisse <marc.glisse_at_[hidden]> wrote:

> On Thu, 25 Apr 2013, Jeffrey Lee Hellrung, Jr. wrote:
>
>  T& a = b + c;
>>>>
>>>> you'll get a compiler error with (A) or (B) and a runtime error with
>>>> (C).
>>>>
>>>
>>> Er, no. That might be true with Microsoft's compiler and its extra
>>> "features", but regular compilers will complain:
>>>
>>> error: invalid initialization of non-const reference of type 'T&' from an
>>> rvalue of type 'T'
>>>
>>
>> Are you sure we're talking about the same thing? This looks like the kind
>> of error that (A) or (B) would produce; would not (C) say something like
>>
>> invalid initialization of non-const reference of type 'T&' from type 'T&&'
>>
>> ???
>>
>> I swear I just tried a T& y = static_cast<T&&>(x) on gcc and finding it
>> compiled fine.
>>
>
> I just tried to compile this program with g++ -std=c++0x -Wall -c test.cc
> for versions of gcc: 4.4, 4.6, 4.7, and 4.9 and they all rejected it with
> pretty much the same error message. I don't understand what the difference
> can be with your tests :-(
>
> struct A{};
> void f(){
>   A a;
>   A&r=static_cast<A&&>(a);
> }
>
> And for the record, clang++'s error message:
>
> error: non-const lvalue reference to type 'A' cannot bind to a temporary
> of type 'A'

Yeah I probably tried it too quickly and screwed something up; I get errors
now. Thanks for setting me straight!

- Jeff