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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:03 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:03 +0000 |
commit | 64d98f8ee037282c35007b64c2649055c56af1db (patch) | |
tree | 5492bcf97fce41ee1c0b1cc2add283f3e66cdab0 /tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs | |
parent | Adding debian version 1.67.1+dfsg1-1. (diff) | |
download | rustc-64d98f8ee037282c35007b64c2649055c56af1db.tar.xz rustc-64d98f8ee037282c35007b64c2649055c56af1db.zip |
Merging upstream version 1.68.2+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs')
-rw-r--r-- | tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs b/tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs new file mode 100644 index 000000000..662c32af1 --- /dev/null +++ b/tests/ui/transmutability/visibility/should_reject_if_dst_has_tricky_unreachable_field.rs @@ -0,0 +1,51 @@ +// check-pass +//! NOTE: This test documents a known-bug in the implementation of the +//! transmutability trait. Once fixed, the above "check-pass" header should be +//! removed, and an "ERROR cannot be safely transmuted" annotation should be added at the end +//! of the line starting with `assert::is_transmutable`. +//! +//! Unless visibility is assumed, a transmutation should be rejected if the +//! destination type contains an unreachable field (e.g., a public field with a +//! private type). (This rule is distinct from type privacy, which still may +//! forbid naming such types.) +//! +//! This test exercises a tricky-to-implement instance of this principle: the +//! "pub-in-priv trick". In the below example, the type `dst::private::Zst` is +//! unreachable from `Context`. Consequently, the transmute from `Src` to `Dst` +//! SHOULD be rejected. + +#![crate_type = "lib"] +#![feature(transmutability)] +#![allow(dead_code)] + +mod assert { + use std::mem::BikeshedIntrinsicFrom; + + pub fn is_transmutable<Src, Dst, Context>() + where + Dst: BikeshedIntrinsicFrom<Src, Context> // safety is NOT assumed + {} +} + +mod src { + #[repr(C)] pub(in super) struct Zst; + + #[repr(C)] pub(in super) struct Src { + pub(in super) field: Zst, + } +} + +mod dst { + mod private { + #[repr(C)] pub struct Zst; // <- unreachable type + } + + #[repr(C)] pub(in super) struct Dst { + pub(in super) field: private::Zst, + } +} + +fn test() { + struct Context; + assert::is_transmutable::<src::Src, dst::Dst, Context>(); +} |