[jira] Created: (STDCXX-955) infinite loop or out of bound access when slicing valarray

[Travis Vitek (JIRA)]

infinite loop or out of bound access when slicing valarray
----------------------------------------------------------

                 Key: STDCXX-955
                 URL: https://issues.apache.org/jira/browse/STDCXX-955
             Project: C++ Standard Library
          Issue Type: Bug
          Components: 26. Numerics
    Affects Versions: 4.2.1
            Reporter: Travis Vitek
            Assignee: Travis Vitek
             Fix For: 4.2.2


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.

{noformat}
#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;
}
{noformat}

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.

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

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