Don't use dangling NonNull as sentinel #3289
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tustvold
commented
Dec 7, 2022
| unsafe fn null_pointer() -> NonNull<u8> { | ||
| NonNull::new_unchecked(ALIGNMENT as *mut u8) | ||
| fn dangling() -> NonNull<u8> { | ||
| // SAFETY: ALIGNMENT is a non-zero usize which is then casted |
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This is copy-pasted from https://doc.rust-lang.org/src/core/ptr/non_null.rs.html#90
tustvold
commented
Dec 7, 2022
| #[inline] | ||
| unsafe fn null_pointer() -> NonNull<u8> { |
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This isn't actually unsafe see https://doc.rust-lang.org/std/ptr/struct.NonNull.html#method.dangling
viirya
reviewed
Dec 8, 2022
| NonNull::new_unchecked(ALIGNMENT as *mut u8) | ||
| fn dangling() -> NonNull<u8> { | ||
| // SAFETY: ALIGNMENT is a non-zero usize which is then casted | ||
| // to a *mut T. Therefore, `ptr` is not null and the conditions for |
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nit: there is no ptr so might be confused for some readers.
viirya
approved these changes
Dec 8, 2022
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Which issue does this PR close?
Closes #.
Rationale for this change
Aside from a method called
null_pointerreturning aNonNullbeing slightly oxymoronic, using the returned value as a sentinel could in extremely unlikely situations lead to a false positive. This would only ever result in leaking memory, but we might as well clean it up.What changes are included in this PR?
Are there any user-facing changes?