I'm writing some unsafe code and it has a pointer whose lifetime is managed manually by the library logic. Right now I just have a comment over the struct field that says that this value must not be copied. Is it possible to enforce this constraint using the type system? Maybe a NoCopy wrapper that causes a compilation error if the code tries copying/cloning this field containing the pointer?
You could define a newtype that doesn’t implement Copy or Clone to hold the pointer:
#[repr(transparent)]
struct NonCopyPtr<T:?Sized>(pub mut* T)
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Wouldn't let p = non_copy_ptr.0 make a copy?
Yes, but it will prevent a Copy or Clone derive from being added to the containing struct. You can also remove the pub from the field to prevent external code from being able to make a copy, leaving only what you explicitly allow.
Preventing absolutely all copies would be counter-productive, as then there would be no way to access the memory that the pointer points to.
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