This is the mail archive of the
libstdc++@gcc.gnu.org
mailing list for the libstdc++ project.
Incorrect char extraction code
- To: "'libstdc++ at gcc dot gnu dot org'" <libstdc++ at gcc dot gnu dot org>
- Subject: Incorrect char extraction code
- From: "Rosen, Hyman" <Hyman dot Rosen at kbcfp dot com>
- Date: Mon, 29 Jan 2001 10:12:38 -0500
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 &>,
and then you need to verify that you won't run afoul of gcc's alias
detection.