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7b97a5ca84
Emit explanatory note for move errors in packed struct derives Derive expansions for packed structs with non-`Copy` fields cause move errors because they prefer copying over borrowing since borrowing the fields of a packed struct can result in unaligned access. This underlying cause of the errors, however, is not apparent to the user. This PR adds a diagnostic note to make it clear to the user (the new note is on the second last line): ``` tests/ui/derives/deriving-with-repr-packed-move-errors.rs:13:16 | 12 | #[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Default)] | ----- in this derive macro expansion 13 | struct StructA(String); | ^^^^^^ move occurs because `self.0` has type `String`, which does not implement the `Copy` trait | = note: `#[derive(Debug)]` triggers a move because taking references to the fields of a packed struct is undefined behaviour = note: this error originates in the derive macro `Debug` (in Nightly builds, run with -Z macro-backtrace for more info) ``` Fixes #117406 Partially addresses #110777 |
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| .. | ||
| constraints | ||
| diagnostics | ||
| region_infer | ||
| type_check | ||
| util | ||
| borrow_set.rs | ||
| borrowck_errors.rs | ||
| constraint_generation.rs | ||
| consumers.rs | ||
| dataflow.rs | ||
| def_use.rs | ||
| facts.rs | ||
| invalidation.rs | ||
| lib.rs | ||
| location.rs | ||
| member_constraints.rs | ||
| nll.rs | ||
| path_utils.rs | ||
| place_ext.rs | ||
| places_conflict.rs | ||
| prefixes.rs | ||
| renumber.rs | ||
| session_diagnostics.rs | ||
| universal_regions.rs | ||
| used_muts.rs | ||