Actually, the best way to learn about std::expected is a funny talk by the (in)famous Andrei Alexandrescu: “Expect the Expected!” What std::expected is, and when it’s used Here are three complementing explanations of what an std::expected<T, E> is: It is the return type of a function which is supposed to return a T value – … Read more
In addition to the paragraphs quoted in the question, there is paragraph 6.4.4.5/3: The keywords false and true are constants of type bool with a value of 0 for false and 1 for true. and 6.6/7: An identifier that is: […] — a predefined constant; […] is a named constant That makes false a named … Read more
Thanks for reminding me of how pointless this feature is. The correct answer is: no, that’s not a well-formed lambda. The grammar is defined in [expr.prim.lambda.general]: In our case, to start with we have: []<auto> noexcept requires true {}; [] is the lambda-introducer <auto> matches <template-parameter-list> and now we know we’re the 2nd kind lambda-expression. … Read more
C++ imposes very few restrictions on the behavior of float and other floating-point types. This can lead to possible inconsistencies in the results, both between compilers, and between runtime/compile-time evaluation by the same compiler. Here is the tl;dr on it: At runtime In constant expressions Floating-point errors, like division by zero UB, but compilers may … Read more
Here are three excerpts from P1413R3: Background aligned_* are harmful to codebases and should not be used. At a high level: Using aligned_* invokes undefined behavior (The types cannot provide storage.) The guarantees are incorrect (The standard only requires that the type be at least as large as requested but does not put an upper … Read more