language-lawyer – Tarik Billa

Is it legal for the compiler to degrade the time complexity of a program? Is this considered observable behavior?

June 12, 2023 by Tarik

The C standard doesn’t actually have a time complexity model, neither for its primitive operations, nor its library functions, so compilers are allowed to do pretty much anything that preserves program semantics (observable behavior). The C++ standard only gives complexity guarantees only for some its library functions, and says (17.5.1.4 [structure.specifications]): Complexity requirements specified in … Read more

Why is unique_ptr not equality_comparable_with nullptr_t in C++20?

April 9, 2023 by Tarik

TL;DR: std::equality_comparable_with<T, U> requires that both T and U are convertible to the common reference of T and U. For the case of std::unique_ptr<T> and std::nullptr_t, this requires that std::unique_ptr<T> is copy-constructible, which it is not. Buckle in. This is quite the ride. Consider me nerd-sniped. Why don’t we satisfy the concept? std::equality_comparable_with requires: template … Read more

Why is James Bond in the working draft of the C++ standard?

April 6, 2023 by Tarik

It’s a joke. Timur Doumler did a lightning talk “ISO/IEC 14882” at CppCon 2019 where he listed this and similar jokes and easter eggs from the standard. And yes, these are part of the official standard document, not just the draft.