![]() Make `Copy` unsafe to implement for ADTs with `unsafe` fields As a rule, the application of `unsafe` to a declaration requires that use-sites of that declaration also entail `unsafe`. For example, a field declared `unsafe` may only be read in the lexical context of an `unsafe` block. For nearly all safe traits, the safety obligations of fields are explicitly discharged when they are mentioned in method definitions. For example, idiomatically implementing `Clone` (a safe trait) for a type with unsafe fields will require `unsafe` to clone those fields. Prior to this commit, `Copy` violated this rule. The trait is marked safe, and although it has no explicit methods, its implementation permits reads of `Self`. This commit resolves this by making `Copy` conditionally safe to implement. It remains safe to implement for ADTs without unsafe fields, but unsafe to implement for ADTs with unsafe fields. Tracking: #132922 r? ```@compiler-errors``` |
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This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Why Rust?
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Performance: Fast and memory-efficient, suitable for critical services, embedded devices, and easily integrated with other languages.
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Reliability: Our rich type system and ownership model ensure memory and thread safety, reducing bugs at compile-time.
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Productivity: Comprehensive documentation, a compiler committed to providing great diagnostics, and advanced tooling including package manager and build tool (Cargo), auto-formatter (rustfmt), linter (Clippy) and editor support (rust-analyzer).
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