Trait std::marker::Unsize
pub trait Unsize<T> where T: ?Sized, { }
Types that can be “unsized” to a dynamically-sized type.
For example, the sized array type [i8; 2]
implements Unsize<[i8]>
and Unsize<dyn fmt::Debug>
.
All implementations of Unsize
are provided automatically by the compiler.
Unsize
is implemented for:
-
[T; N]
isUnsize<[T]>
-
T
isUnsize<dyn Trait>
whenT: Trait
-
Foo<..., T, ...>
isUnsize<Foo<..., U, ...>>
if:T: Unsize<U>
- Foo is a struct
- Only the last field of
Foo
has a type involvingT
-
T
is not part of the type of any other fields -
Bar<T>: Unsize<Bar<U>>
, if the last field ofFoo
has typeBar<T>
Unsize
is used along with ops::CoerceUnsized
to allow “user-defined” containers such as Rc
to contain dynamically-sized types. See the DST coercion RFC and the nomicon entry on coercion for more details.
Implementors
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/marker/trait.Unsize.html