Re: Incorrect char extraction code

[Phil Edwards <pedwards at disaster dot jaj dot com>]

On Tue, Jan 30, 2001 at 09:22:48AM +0000, Jason Merrill wrote:
> >>>>> "Rosen," == Rosen, Hyman <Hyman.Rosen@kbcfp.com> writes:
> 
> > std_istream.h has the following pair of templates:
> >   template<class _Traits>
> >     basic_istream<char, _Traits>&
> operator> (basic_istream<char, _Traits>& __in, unsigned char& __c)
> >     { return (__in >> static_cast<char>(__c)); }
> 
> >   template<class _Traits>
> >     basic_istream<char, _Traits>&
> operator> (basic_istream<char, _Traits>& __in, signed char& __c)
> >     { return (__in >> static_cast<char>(__c)); }
> 
> > These are clearly wrong; the result of a static_cast<char> is not an
> > lvalue, so code that tries an extraction into a signed or unsigned char
> > shouldn't even compile. Those casts need to be reinterpret_cast<char &>,
> 
> Yes.

Before I make that change... why *does* the code compile?  I can successfully
perform extractions into a signed or unsigned char presently.  (Which is
wrong, as you say; I just want to know why we're allowing it.)


Phil

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