C++20

The next major revision of the C++ standard

Following features are about to be merged into C++20:

1. From TS's: Coroutines, Modules, Constraints and concepts, abbreviated function templates,
2. From TS's: Ranges, uniform container erasure (std::erase/std::erase_if)

New language features

• Feature test macros
• 3-way comparison operator <=> and operator==() = default
• designated initializers
• init-statements and initializers in range-for
• char8_t
• [[no_unique_address]]
• [[likely]]
• [[unlikely]]
• pack-expansions in lambda captures
• removed the requirement to use typename to disambiguate types in many contexts
• consteval, constinit
• further relaxed constexpr
• signed integers are 2's complement
• aggregate initialization using parentheses
• Coroutines
• Modules
• Concepts
• abbreviated function templates
• DR: array new can deduce array size

New library features

New headers

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in Thread support library:

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Library features

• Formatting library
• Calendar and Time Zone library
• std::source_location
• std::span
• std::endian
• array support for std::make_shared
• std::remove_cvref
• std::to_address
• floating point and shared_ptr atomics
• std::barrier, std::latch, and std::counting_semaphore
• std::jthread and thread cancellation classes
• <version>
• std::osyncstream
• std::u8string and other char8_t uses
• constexpr for <algorithm>, <utility>, <complex>
• std::string(_view)::starts_with and ends_with
• std::assume_aligned
• std::bind_front
• std::c8rtomb/std::mbrtoc8
• std::make_obj_using_allocator etc
• std::make_shared_for_overwrite/std::make_unique_for_overwrite
• heterogeneous lookup in unordered associative containers
• std::polymoprhic_allocator with additional member functions and std::byte as its default template argument
• std::execution::unseq
• std::midpoint and std::lerp
• std::ssize
• std::is_bounded_array
• Ranges
• uniform container erasure (std::erase/std::erase_if)
• Mathematical constants

Compiler support

Main Article: C++ compiler support Predefinição:cpp/compiler support/20 Predefinição:cpp/compiler support/note

• Working c++20 examples