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From: Eric Niebler (eric_at_[hidden])
Date: 2005-03-23 13:01:21

Jonathan Wakely wrote:
> On Wed, Mar 23, 2005 at 04:06:09PM +0000, Joaquin M Lopez Munoz wrote:
>>"I can't think of any way that this extension could
>>break a conforming program, considering that users
>>are not permitted to forward-declare standard
>>library components"
>>Is this really so? Why cannot I forward declare a
>>stdlib component?
> Opening namespace std for anything except specialisations of standard
> library templates (with user-defined types as parameters) is illegal.

OK, but that has never stopped us (Boost) from doing it before.
config/suffix.hpp defines std::min and std::max for non-compliant std
libs. lambda/detail/operator_return_type_traits.hpp forward-declares
std::complex<>. I don't see anything particularly wrong with that,
except that perhaps forward-declarations of std types should be moved
into the config sub-project to better handle the variety in different
std libs.

Eric Niebler
Boost Consulting

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