He clicked .

Tomorrow, he would refactor it to C++20. He heard std::span was finally stable. But tonight, he had earned his sleep.

The "Big Four" features of C++20 were the talk of the community in 2019. First, finally brought constrained templates to the language after decades of proposals. This feature promised to replace the cryptic, pages-long template error messages that plagued developers with clear, enforceable constraints, making generic programming accessible to the average developer rather than just library authors.