Re: [boost] any

From: Kevlin Henney (kevlin_at_[hidden])
Date: 2000-09-04 04:41:52

In message <001201c015d9$5cfdd740$309a60cb_at_yogi>, Mark Rodgers
<mark.rodgers_at_[hidden]> writes
>> It already works for this case. The type check is performed using the
>> result of typeid rather than dynamic_cast: dynamic_cast<holder<const
>> int> *> would fail but typeid(int) == typeid(const int) is true, so it
>> works as it stands -- no deconsting through traits is required.
>
>Not OK.  The way typeid strips off cv-qualifiers is the problem.  Yes,
>this does compile, and works in probably 99% of cases, but the result
>is still undefined.  As you note, the dynamic_cast would fail, which
>indicates that the static_cast is invalid.  The remove_const is needed
>in the target type of the static_cast (in which case you could dispense
>with the typeid check and just use dynamic_cast).

I believe that the types are layout compatible, and so the problem does
not arise.
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