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Re: Future evolution of c++config.h and _GLIBCXX_USE_LONG_LONG


On Jan 11, 2005, at 3:45 PM, Paolo Carlini wrote:

Matt Austern wrote:

I suppose another question that's implicit but that I didn't ask is: would it be a desirable feature to give users a way of getting a fully conforming C++ language/library implementation without having to reconfigure and reinstall? Should there be a compiler switch that does that?

As far as the library is concerned, having _GLIBCXX_USE_LONG_LONG
always defined (or removing the macro completely) basically means having a
few additional num_get::do_get and num_put::do_put overloads defined, besides
what is mandated by the current standard. I don't think this can really hurt, but
perhaps you or Benjamin or Gaby could explain in gory technical details the
risks of this, which, honestly, I fail to really grasp.

The danger is really on the Libc side. According to the C++ standard, the following program is valid:
#define lldiv_t 0
#include <iostream>
int main() { return lldiv_t; }


No sane person would do this (other than a test suite writer), but it is valid.

--Matt


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