P3242: LEWG Review 3/27/2026

[nmm0]

Motivating example:

std::mdspan src{src_ptr, src_exts};
std::mdspan dst{dst_ptr, dst_exts};

std::fill(src, 5.0);
std::copy(src, dst);

[nmm0]

• Add feature test macro
• Add header in wording
• Non normative note for extent constructability
• Hardened? No consensus but maybe come back later with another paper if we want to do it
• Concerns about implementer burden from parallel -- though in this case this is likely not an issue

[nmm0]

It got forwarded to LWG for C++29.

I realized just now I had forgotten constexpr in the wording...