Fix packed structs with flexible array members #3305
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Wrap the FAM generic parameter in `ManuallyDrop` when the parent struct is packed. This satisfies Rust's requirement that DST fields in packed structs must not need `Drop` to be run. The fix automatically detects packed structs and generates: pub field: ::std::mem::ManuallyDrop<FAM> instead of: pub field: FAM Fixes rust-lang#2936
emilio
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Oct 21, 2025
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Summary: This includes 3 recent PRs: - rust-lang/rust-bindgen#3305 - Fix packed structs with flexible array members (merged) - rust-lang/rust-bindgen#3306 - Support nested flexible array members - rust-lang/rust-bindgen#3307 - Add support for custom per-field attributes The last one is specifically intended to allow per-field attributes from proc-macros to be applied. These have been cherry-picked onto the v0.72.1 release branch, as the main branch is still listed as v0.72.0 and I didn't want a backwards version step. The upstream branch is https://github.com/jsgf/rust-bindgen/tree/PR-merged Reviewed By: dtolnay Differential Revision: D85273915 fbshipit-source-id: 211916b9611cbfa409296a6854b4a94bba2c5195
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Summary: This includes 3 recent PRs: - rust-lang/rust-bindgen#3305 - Fix packed structs with flexible array members (merged) - rust-lang/rust-bindgen#3306 - Support nested flexible array members - rust-lang/rust-bindgen#3307 - Add support for custom per-field attributes The last one is specifically intended to allow per-field attributes from proc-macros to be applied. These have been cherry-picked onto the v0.72.1 release branch, as the main branch is still listed as v0.72.0 and I didn't want a backwards version step. The upstream branch is https://github.com/jsgf/rust-bindgen/tree/PR-merged Reviewed By: dtolnay Differential Revision: D85273915 fbshipit-source-id: 211916b9611cbfa409296a6854b4a94bba2c5195
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Wrap the FAM generic parameter in
ManuallyDropwhen the parent struct is packed. This satisfies Rust's requirement that DST fields in packed structs must not needDropto be run.The fix automatically detects packed structs and generates:
pub field: ::std::mem::ManuallyDrop
instead of:
pub field: FAM
Fixes #2936