Re: (N2118)Rvalue reference may create a loophole in the type system

From:

dave@boost-consulting.com (David Abrahams)

Newsgroups:

comp.std.c++

Date:

Thu, 19 Jul 2007 15:24:50 GMT

Message-ID:

<87abtscudx.fsf@grogan.peloton>

on Thu Jul 19 2007, pongba-AT-gmail.com wrote:

In particular I'm considering the following code:

int&& i = 0;
i++;

this actually compiles(because a named rvalue reference is treated as
a lvalue for safety reasons(e.g. moved more than once)), which is very
bothersome, because the whole point of the current wording that
forbids non-const reference to bind to rvalue is to prevent users from
modifying a rvalue through a reference.

rvalue references provide a way to _explicitly_ circumvent that rule.
That's a major feature, without which rvalue references would be
useless.

One might consider prohibiting auto ("on the stack") rvalue
references, though. I'm not sure whether they're useful. Howard?

--
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com

The Astoria Seminar ==> http://www.astoriaseminar.com

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