libstdc++/8851: Slice_array assignment changes right side, leaves left side unchanged.

[agenkin@dimacs.rutgers.edu]

>Number:         8851
>Category:       libstdc++
>Synopsis:       Slice_array assignment changes right side, leaves left side unchanged.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 06 14:26:00 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Alexander Genkin
>Release:        gcc version 3.2 20020927
>Organization:
>Environment:
Cygwin
>Description:
Slice_array assignment changes right side, leaves left side unchanged.

#include <iostream>
#include <valarray>
using namespace std;

std::ostream& operator<<( std::ostream& s, const valarray<double>& vad ) {
    for( size_t i=0; i<vad.size(); i++ ) s<<vad[i]<<" ";
    return s;
}

int main() {
    valarray<double> a(1.0,9);
    valarray<double> b(2.0,9);

    b[slice(0,3,3)] = a[slice(2,3,3)];
    cout<<endl<<"a "<<a;
    cout<<endl<<"b "<<b;

    return 0;
}

Output is:
a 1 1 2 1 1 2 1 1 2
b 2 2 2 2 2 2 2 2 2
>How-To-Repeat:

>Fix:

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