precompiled header files (PCH)  Custom headers can also be made importable, but how to is compiler dependent “How C++20 Changes the Way We Write Code” -- Timur Doumler Friday, September 18 • 12:00Ranges11 Can be used to implement any other synchronization concept: mutex, latches, barriers, …  Two types:  counting semaphore: models a non-negative resource count  binary semaphore: only has 1 slot Non-defaulted (then you also need to write an operator==)  Custom implementation  Choice of three return types: strong_ordering, partial_ordering, or weak_ordering50 Spaceship Operator <=>  Example: int

Features  Garbage Collection Support30 Assumptions  Before C++23, assumptions are compiler dependent  Examples:  MSVC and ICC: __assume(expr)  Clang: __builtin_assume(expr)  GCC: Emulated std::views::adjacent_transform<2>(std::multiplies()) }// {2,6,12}79 Changes to Views Library  Two helper types:  views::pairwise = views::adjacent<2>  views::pairwise_transform = views::adjacent_transform<2> Collection Support97 std::byteswap()  Defined in  Standard way to swap bytes of integral types  E.g.: std::uint32_t a{ 0x12345678u }; std::println("{:x}", a); // 12345678 std::uint32_t b{

Counted link Solutions for Dependent Retirement Hazard Pointer Synchronous Reclamation Beyond Concurrency TS2 – Maged Michael • Maintain an indicator of automatic dependent retirement. • Clear indicator Automatically repeat global cleanup if dependent retirement happens. • Implication: Asynchronous reclamation must be transitive and keep repeating whenever dependent retirement happens. • Folly supports hazard_pointer_clean_up. • Weaker: Doesn’t cover all retired objects. • Stronger: Seamlessly handles dependent retirement. Cohort Interface Hazard Pointer Synchronous Reclamation Beyond Concurrency TS2 – Maged

support • Publish code to GitHub or Azure Devops • Pinning branches & customizations • Hot Reload • Dependent breakpoints & Force run to cursor • And… performance Performance of Visual Studio Build

I: Development Process • Implementing in the Open • Organization of Work • Part II: Calendrical Types • Part III: Clocks • Part IV: Leap Seconds • What are leap seconds? • How did we implement them second awareness (https://youtu.be/c7DT28TV0AY)9 Part II: Calendrical Types10 Calendrical Types ([time.cal]) • Lots of new class types • chrono::day • chrono::month • chrono::year • chrono::month_day • chrono::year_month_day_last • chrono::year_month_weekday_last • …11 Some examples: Simple Calendrical Types #include #include using namespace std::chrono; int main() { year y{2021};

type: CREATE TABLE games (data JSON) ENGINE = MergeTree; • You can insert arbitrary nested JSONs • Types are automatically inferred on INSERT and merge • Data is stored in columnar format: columns and subcolumns For Semistructured Data <-- inferred type DESCRIBE TABLE games SETTINGS describe_extend_object_types = 1 name: data type: Tuple( `_id.$oid` String, `date.$date` String, `teams.abbreviation` Array(String) columns with strict and flexible schema in one table • Queries work as fast as with predefined types! Planned for Q1 2022. Developer: Anton Popov. Выводы 31 Вместе с новой компанией и open-source

seconds { 45 } };18 Durations – Predefined & Literals  Warning: predefined durations use integral types, so: seconds s { 90 }; minutes m { s }; // Error duration> m { s }; // 1.519 Agenda sys_time;  Serial-based representations (single number) versus field-based types like (year_month_day)34 Dates  Create a sys_days representing today: auto today { floor 86,400 * ((365 * 400) + 97) / 400) = 31,556,952 seconds37 Dates  You can use field-based types instead auto d2 { sys_days { 2020y / June / 22d } + 9h + 35min + 10s }; // Split d2 into days and

第三届中国 Rust 开发者大会 王俊吉 RustBelt - Rust 的形式化语义模型 Outline Background • RustBelt Project • Rust Types Overview Rust Semantics • Type System • The own Predict • Exclusive Ownership & Mutable Borrow Language Coq Proof Assistant: A Formal Proof Management System built on top of built on top of Rust Types Overview Background T &mut T &T mutable borrow immutable borrow coercion move mutable reborrow

SIZE_MAX. */ size_t open_device(char const* dev); size_t open_device(std::wstring_view const dev); The types char and wchar_t do not indicate encoding. The size of wchar_t: • Windows, sizeof(wchar_t) == 2 you want and assume. • Understand assumptions and be precise when possible. • C++ now has many types that express precisely what is meant – integer sizes, string encoding, etc. • Interop scenarios

std::this_thread::sync_wait( read_socket_async(s, buff) ).value(); } AWAITABLES AS SENDERS All awaitable types are senders and can be passed to any async algorithm that accepts a sender. No extra allocation in which async work can be spawned (fire-and-forget) and stopped and/or joined. Expect coroutine types that are deeply integrated with sender/receiver and ranges: • std::task • std::generator • std