Span with range check

[HenningScheufler]

Span is currently unable to do range checks and this features will be added in 26

https://en.cppreference.com/w/cpp/container/span

I would propose the following:

using NeoFOAM::span = std::span

for debug builds, we would use our on implementation with range checks in the operator[]

What are your toughts do you support the idea?

@greole @gregorweiss @bevanwsjones @MarcelKoch

[bevanwsjones]

I would further say that most containers we make should to quite 'heavy' debug checking in 'debug' mode, then in production it all gets turned off. I would add to the list quite extensive executor compatibility checking, though a separate issue. So I support this very strongly!

[greole]

I think I agree fully, but could you elaborate what you mean by

we would use our on implementation with range checks in the operator[]

[HenningScheufler]

something like this

namespace NeoFOAM
{

// in case of debug use DebugSpan instead of span
using span = std::span;

template<typename T>
class DebugSpan : public std::span<T>
{
public:

    using std::span<T>::span; // Inherit constructors from std::span

    DebugSpan(std::span<T> span) : std::span<T>(span) {}

    constexpr T& operator[](std::size_t index) const
    {
        if (index >= this->size())
        {
            Kokkos::abort("Index out of range in DebugSpan.\n");
        }
        return std::span<T>::operator[](index);
    }
};


} // namespace NeoFOAM

[MarcelKoch]

I think it would be fine if the check can be disabled for release builds.

[greole]

Like this?

namespace NeoFOAM
{

// in case of debug use DebugSpan instead of span
using span = std::span;

template<typename T>
class Span : public std::span<T>
{
public:

    using std::span<T>::span; // Inherit constructors from std::span

    constexpr T& operator[](std::size_t index) const
    { 
    #ifdef DEBUG
        if (index >= this->size())
        {
            Kokkos::abort("Index out of range in DebugSpan.\n");
        }
    #endif
        return std::span<T>::operator[](index);
    }
};


} // namespace NeoFOAM