Hi,

C++0x (N2800) [except.handle]p3 says:

"A handler is a match for an exception object of type E if
 - The handler is of type cv T or cv T& and E and T are the same type
(ignoring the top-level cv-qualifiers), or
..."

Note that this does not allow catch by rvalue reference to succeed,
i.e.

try { ... } catch(T&& t) { /* cannot be used */ }

Intentional or oversight? If intentional, shouldn't it be an ill-
formed program instead?

Sebastian

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On Mar 16, 2:02 am, wasti.r...@gmx.net wrote:
> Hi,
>
> C++0x (N2800) [except.handle]p3 says:
>
> "A handler is a match for an exception object of type E if
>  - The handler is of type cv T or cv T& and E and T are the same type
> (ignoring the top-level cv-qualifiers), or
> ..."
>
> Note that this does not allow catch by rvalue reference to succeed,
> i.e.
>
> try { ... } catch(T&& t) { /* cannot be used */ }
>
> Intentional or oversight? If intentional, shouldn't it be an ill-
> formed program instead?

I believe it was originally an oversight. However, this issue was
discussed at the most recent C++ committee meeting, as part of the
discussion of N2831, a change that prevents rvalue references from
binding to lvalues. This paper effectively made rvalue-reference
handlers useless, since they would never be able to bind to a thrown
exception (which is an lvalue). Therefore, the core working group
decided to make rvalue-reference handlers ill-formed. The change is
part of N2844 (the successor to N2831), which was voted into the
working paper and will appear in the post-Summit mailing.

   - Doug


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