c++/2674: c++ calls by value instead of by reference

["Uwe F. Mayer" <mayer at tux dot org>]

>Number:         2674
>Category:       c++
>Synopsis:       c++ calls by value instead of by reference
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Apr 27 20:46:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Uwe F. Mayer
>Release:        3.0 20010409 (prerelease)
>Organization:
tux.org
>Environment:
System: Linux tosca 2.2.18 #2 Thu Mar 8 13:48:25 PST 2001 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --prefix=/usr/local/gcc --disable-nls
>Description:
When calling a function with a call-by-reference inside a printing
statement the variable does not get updated, effectively calling as
a call-by-value.
>How-To-Repeat:
Compile and run this program:

#include <iostream>
using namespace std;
double f(double& x)
{
  x=1;
  return 2;
}
int main()
{
   double d=5;
   cout << f(d) << "\t" << d << endl;
   // the line below produces correct output of "2    1"
   // double y=f(d); cout << y << "\t" << d << endl;
}

On my system it outputs:
2	5
instead of the correct:
2	1
>Fix:



>Release-Note:
>Audit-Trail:
>Unformatted: