[STDCXX-955] infinite loop or out of bound access when slicing valarray

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 4.2.1
• Fix Version/s: 4.2.2
• Component/s: 26. Numerics
• Severity: Runtime Error
• Assignee: Travis Vitek
• Reporter: Travis Vitek
• Created: 04/Jun/08 00:49
• Updated: 07/Jun/08 02:10
• Resolved: 07/Jun/08 02:10

Description

The current valarray code does not handle creating a gslice that has a one or more empty steps. The following testcase will hang in an infinite loop.

#include <cstdlib>
#include <valarray>


int main ()
{
    const std::size_t p_leng [] = { 0 };
    const std::size_t p_strd [] = { 0 };

    const std::valarray<std::size_t> va_leng (p_leng,
        sizeof (p_leng) / sizeof (*p_leng));

    const std::valarray<std::size_t> va_strd (p_strd,
        sizeof (p_strd) / sizeof (*p_strd));

    const std::gslice gs_slice (1, va_leng, va_strd);

    std::valarray<char> va_lhs (10, '!');

    va_lhs [gs_slice] = '?';

   return 0;
}

Changing the declarations of p_len and p_strd to the following will result in an assertion or an out of bound access depending on build type.

    const std::size_t p_leng [] = { 2, 0 };
    const std::size_t p_strd [] = { 1, 3 };