pub static REPR_TRANSPARENT_EXTERNAL_PRIVATE_FIELDS: &Lint
Expand description
The repr_transparent_external_private_fields
lint
detects types marked #[repr(transparent)]
that (transitively)
contain an external ZST type marked #[non_exhaustive]
or containing
private fields
Example
ⓘ
#![deny(repr_transparent_external_private_fields)]
use foo::NonExhaustiveZst;
#[repr(transparent)]
struct Bar(u32, ([u32; 0], NonExhaustiveZst));
This will produce:
error: zero-sized fields in repr(transparent) cannot contain external non-exhaustive types
--> src/main.rs:5:28
|
5 | struct Bar(u32, ([u32; 0], NonExhaustiveZst));
| ^^^^^^^^^^^^^^^^
|
note: the lint level is defined here
--> src/main.rs:1:9
|
1 | #![deny(repr_transparent_external_private_fields)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #78586 <https://github.com/rust-lang/rust/issues/78586>
= note: this struct contains `NonExhaustiveZst`, which is marked with `#[non_exhaustive]`, and makes it not a breaking change to become non-zero-sized in the future.
Explanation
Previous, Rust accepted fields that contain external private zero-sized types, even though it should not be a breaking change to add a non-zero-sized field to that private type.
This is a future-incompatible lint to transition this to a hard error in the future. See issue #78586 for more details.