Delete C++ move operations for non-copyable Clone types#758
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Delete C++ move operations for non-copyable Clone types#758copybara-service[bot] wants to merge 1 commit intomainfrom
copybara-service[bot] wants to merge 1 commit intomainfrom
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Previously, Crubit would generate C++ move constructors for Rust types that implemented `Clone` but not `Copy` by deferring them to `MoveCtorStyle::Copy`. This would silently invoke the C++ copy constructor (and underlying Rust `Clone::clone`) instead of performing an actual move. By itself, this is not harmful at all. This caused severe memory leaks when crossing the FFI boundary within TansmuteAbi, however. For example, when `crubit::TransmuteAbi` decodes bytes into a C++ object, it takes the raw bytes from Rust and attempts to `std::move` them into ownership. Because the move constructors were falling back to deep copies, the new C++ object was a copied clone, and the original raw bytes (owning things like `Box`) were abandoned without `Drop::drop` ever being called. This CL removes `MoveCtorStyle::Copy` so that C++ move operations are explicitly deleted (`= delete`) for non-trivially movable `Clone` types. This correctly turns silent deep-copy memory leaks into compile-time errors. PiperOrigin-RevId: 889377273
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Delete C++ move operations for non-copyable Clone types
Previously, Crubit would generate C++ move constructors for Rust types that implemented
Clonebut notCopyby deferring them toMoveCtorStyle::Copy. This would silently invoke the C++ copy constructor (and underlying RustClone::clone) instead of performing an actual move. By itself, this is not harmful at all.This caused severe memory leaks when crossing the FFI boundary within TansmuteAbi, however. For example, when
crubit::TransmuteAbidecodes bytes into a C++ object, it takes the raw bytes from Rust and attempts tostd::movethem into ownership. Because the move constructors were falling back to deep copies, the new C++ object was a copied clone, and the original raw bytes (owning things likeBox) were abandoned withoutDrop::dropever being called.This CL removes
MoveCtorStyle::Copyso that C++ move operations are explicitly deleted (= delete) for non-trivially movableClonetypes. This correctly turns silent deep-copy memory leaks into compile-time errors.