| @@ -779,6 +779,15 @@ where |
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/// |
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/// For `r: &T`, `from_ref(r)` is equivalent to `r as *const T`, but is a bit safer since it will |
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/// never silently change type or mutability, in particular if the code is refactored. |
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+/// |
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+/// The caller must ensure that the pointee outlives the pointer this function returns, or else it |
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+/// will end up pointing to garbage. |
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+/// |
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+/// The caller must also ensure that the memory the pointer (non-transitively) points to is never |
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+/// written to (except inside an `UnsafeCell`) using this pointer or any pointer derived from it. If |
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+/// you need to mutate the pointee, use [`from_mut`]`. Specifically, to turn a mutable reference `m: |
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+/// &mut T` into `*const T`, prefer `from_mut(m).cast_const()` to obtain a pointer that can later be |
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+/// used for mutation. |
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#[inline(always)] |
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#[must_use] |
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#[stable(feature = "ptr_from_ref", since = "1.76.0")] |
| @@ -791,6 +800,9 @@ pub const fn from_ref<T: ?Sized>(r: &T) -> *const T { |
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/// Convert a mutable reference to a raw pointer. |
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/// |
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+/// The caller must ensure that the pointee outlives the pointer this function returns, or else it |
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+/// will end up pointing to garbage. |
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+/// |
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/// For `r: &mut T`, `from_mut(r)` is equivalent to `r as *mut T`, but is a bit safer since it will |
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/// never silently change type or mutability, in particular if the code is refactored. |
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#[inline(always)] |