namespace pollution

[Prof.Farnsworth@gmx.com]

How about this one:

#include <iostream>
typedef double time_t;

leads to

conflicting types for `typedef double time_t'
/usr/include/time.h:70: previous declaration as `typedef __time_t time_t'

AFAIK, this should not happen when using a std header without .h

Regards,
Philipp