Previously: “span should have a converting constructor from initializer_list”
(2021-10-03). This converting constructor was added by P2447
for C++26. Way back in 2024, Peter Kasting added the same constructor to Chromium’s
base::span —
he emailed me about it at the time — but I was only recently reminded that in
the /r/cpp thread
about the feature he’d written:

Authored by Arthur O'Dwyer, Quuxplusone offers  explorations of C++ programming language features, standard library design, and modern C++ development practices. Readers can delve into advanced topics such as template metaprogramming, design patterns, and effective use of language features. Additionally, they can learn about best practices for writing efficient and maintainable C++ code, optimizing performance, and leveraging the latest language standards.

Arthur O'Dwyer

A close reading of a Chromium commit by Peter Kasting that added a converting constructor from initializer_list to base::span, mirroring the C++26 P2447 proposal. The post walks through real call sites in the codebase that were simplified by the new constructor, showing how three different workarounds (temporary std::array, doubled curly braces, explicit span cast) all converged on cleaner natural syntax. Two 'failure cases' are also examined where the change couldn't fully simplify code due to the lack of CTAD and C++ grammar restrictions on braced initializer lists after operators.

Chromium’s span-over-initializer-list success story