GoKawiilC++23 introduces bitmask support for enums with automatic operators
A new C++23 proposal, P4313R1, adds a [[=std::bitmask_type]] annotation to enums, enabling automatic bitwise operations for enum classes. This feature simplifies working with enums representing flags by eliminating the need to manually define operators, leveraging a C++26 annotation to opt-in. The discussion also highlights how integral promotions affect bitwise operations on smaller types like shorts, which are promoted to int during computation.
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This development could streamline code involving flag enums, reducing boilerplate and potential errors. It also underscores ongoing efforts to improve type safety and clarity in C++, especially when dealing with bitwise operations on various integral types. Understanding how integral promotions influence these operations helps developers write more predictable and bug-resistant code.
- C++23 will support automatic bitwise operators for enums with a new annotation.
- Integral promotions mean smaller types are promoted to int during bitwise operations.
- Developers should consider static_cast to maintain type consistency and avoid bugs.
Source: dryperspective.github.io — Matthew Taylor, 2026-10-04
Published there as: “The complement of true is true, except when it's false”
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