pub unsafe trait Storage:
Sized
+ Deref
+ 'static { }Expand description
Implemented for types that can safely provide a stable, aliasable reference to data they own.
§noalias
The pointers behind common allocation types (Box<T>, Vec<T>, etc), are
stored via core::ptr::Unique<T>, which passes to the compilier a noalias
attribute. This attribute allows the compiler to make optimisations with the
guarantee that no other pointers are referencing the same data.
We want to both own the data and provide a reference to it, outside of
Rust’s normal lifetime guarantees, which can break with some of the
optimisations the compiler can make. To achieve this, we need to remove the
noalias attribute of the underlying pointer to let the compiler know that
there will exist multiple pointers referencing the same owned data, which is
also known as aliasing.
§Safety
The implementer must guarantee that the reference it provides via Deref
will be both stable and aliasable for the lifetime of self. Stable in
this context meaning that the pointer to the data referenced will not
change.
Box<T> provides a stable pointer (the location of the data being pointed
to will not change) but is not aliasable (see noalias above). Instead we
can use the basic wrapper types provided by the aliasable crate.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.