zeroize: support unsized types in Zeroizing #1318
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This commit adds ?Sized to the generic bounds on Zeroizing and many of its trait implementations. This makes it possible to form and use types like `Zeroizing<Box<[u8]>>` and `Zeroizing<Arc<[u8]>>`.
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ssanderson
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Dec 30, 2025
| // This is a weird way to use zeroizing, but it's technically allowed b/c | ||
| // unsized types can be stored inside Zeroizing, so make sure it works as | ||
| // expected. | ||
| #[test] |
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I think this is missing a feature = "alloc" guard since it uses Box, but it seems like the build is still passing. Are these guards actually required?
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Since these tests are in tests/ they're in their own toplevel crate which links alloc and std by default.
You only need to gate alloc if it's using alloc-dependent functionality inside Zeroize. Since this is Box<Zeroizing<[u8]>> and not Zeroizing<Box<[u8]>> (which would need the Zeroize impl on Box) you're not actually dependent on zeroize having its alloc feature enabled.
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This commit adds
?Sizedto the generic bounds on Zeroizing and many of its trait implementations. This makes it possible to form and use types likeZeroizing<Box<[u8]>>andZeroizing<Arc<[u8]>>.This also allows forming more exotic types like
Zeroizing<dyn SomeTrait>whereSomeTrait: Zeroize. I've included a test for that case to ensure that nothing unexpected breaks if it's used in that way, but that usage is probably not to be recommended.See #1256 for more details.