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| author | Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com> | 2022-02-15 20:16:19 +0100 |
|---|---|---|
| committer | Daniel Henry-Mantilla <daniel.henry.mantilla@gmail.com> | 2022-02-16 13:29:00 +0100 |
| commit | 6d2cdbec3ef6e5460753986372ed898a1b3bc553 (patch) | |
| tree | f7fd3ce176fe84e15647e17cd1accd9998d9b9fd /compiler | |
| parent | 6421a499a50adbaa7b5d0234bdd4817d970f0933 (diff) | |
| download | rust-6d2cdbec3ef6e5460753986372ed898a1b3bc553.tar.gz rust-6d2cdbec3ef6e5460753986372ed898a1b3bc553.zip | |
Add mentions to `Copy` for `union` fields
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_typeck/src/check/check.rs | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/compiler/rustc_typeck/src/check/check.rs b/compiler/rustc_typeck/src/check/check.rs index 423abc3227d..ca2e75886c7 100644 --- a/compiler/rustc_typeck/src/check/check.rs +++ b/compiler/rustc_typeck/src/check/check.rs @@ -382,10 +382,15 @@ fn check_union_fields(tcx: TyCtxt<'_>, span: Span, item_def_id: LocalDefId) -> b tcx.sess, field_span, E0740, - "unions may not contain fields that need dropping" + "unions cannot contain fields that may need dropping" + ) + .note( + "a type is guaranteed not to need dropping \ + when it implements `Copy`, or when it is the special `ManuallyDrop<_>` type", ) .multipart_suggestion_verbose( - "wrap the type with `std::mem::ManuallyDrop` and ensure it is manually dropped", + "when the type does not implement `Copy`, \ + wrap it inside a `ManuallyDrop<_>` and ensure it is manually dropped", vec![ (ty_span.shrink_to_lo(), format!("std::mem::ManuallyDrop<")), (ty_span.shrink_to_hi(), ">".into()), |