1 files changed, 0 insertions, 142 deletions
diff --git a/vendor/yoke/src/is_covariant.rs b/vendor/yoke/src/is_covariant.rs
deleted file mode 100644
index 75d123c84..000000000
--- a/vendor/yoke/src/is_covariant.rs
+++ /dev/null
@@ -1,142 +0,0 @@
-// This file is part of ICU4X. For terms of use, please see the file
-// called LICENSE at the top level of the ICU4X source tree
-// (online at: https://github.com/unicode-org/icu4x/blob/main/LICENSE ).
-
-#[cfg(feature = "alloc")]
-use alloc::{
-    borrow::{Cow, ToOwned},
-    boxed::Box,
-    rc::Rc,
-    string::String,
-};
-
-/// A type implementing `IsCovariant<'a>` is covariant with respect to lifetime `'a`.
-///
-/// Lifetime parameters that are safely cast in [`Yokeable`] are also valid for `IsCovariant`.
-///
-/// `IsCovariant` exists primarily to serve in trait bounds. The primary use case is to safely
-/// perform lifetime casting on trait objects (`dyn Trait`). This enables a type-erased [`Yoke`]
-/// consisting of only trait objects. See the examples.
-///
-/// `IsCovariant` is auto-implemented in [`#[derive(Yokeable)]`](macro@crate::Yokeable).
-///
-/// # Safety
-///
-/// This trait is safe to implement on types with a _covariant_ lifetime parameter. This will
-/// occur when the lifetime parameter is used within references, but not in the arguments of
-/// function pointers or in mutable positions (either in `&mut` or via interior mutability).
-///
-/// If a struct has multiple lifetime parameters, only the one used in `IsCovariant<'a>` needs to
-/// be covariant.
-///
-/// # Examples
-///
-/// Implementing on a simple struct with a single covariant lifetime:
-///
-/// ```
-/// # use yoke::*;
-/// struct MyStruct<'a>(&'a str);
-///
-/// // This is safe because 'a is covariant
-/// unsafe impl<'a> IsCovariant<'a> for MyStruct<'a> {}
-/// ```
-///
-/// By constraining the trait `ExampleTrait<'a>` on `IsCovariant<'a>`, we can safely implement
-/// [`Yokeable`] and [`ZeroFrom`] on its trait object:
-///
-/// ```
-/// # use yoke::*;
-/// # use zerofrom::*;
-/// # use core::mem;
-/// trait ExampleTrait<'a>: IsCovariant<'a> {
-///     fn get_message(&self) -> &'a str;
-/// }
-///
-/// // This wrapper is required because of the blanket Yokeable impl on &'static T
-/// pub struct ExampleTraitDynRef<'a>(pub &'a dyn ExampleTrait<'a>);
-///
-/// // The following impl is safe because the trait object requires IsCovariant.
-/// unsafe impl<'a> Yokeable<'a> for ExampleTraitDynRef<'static> {
-///     type Output = ExampleTraitDynRef<'a>;
-///     fn transform(&'a self) -> &'a Self::Output {
-///         unsafe { mem::transmute(self) }
-///     }
-///
-///     fn transform_owned(self) -> Self::Output {
-///         unsafe { mem::transmute(self) }
-///     }
-///
-///     unsafe fn make(from: Self::Output) -> Self {
-///         unsafe { mem::transmute(from) }
-///     }
-///
-///     fn transform_mut<F>(&'a mut self, f: F)
-///     where
-///         F: 'static + FnOnce(&'a mut Self::Output),
-///     {
-///         unsafe { f(mem::transmute::<&mut Self, &mut Self::Output>(self)) }
-///     }
-/// }
-///
-/// impl<'zf, 'a> ZeroFrom<'zf, dyn ExampleTrait<'a> + 'a> for ExampleTraitDynRef<'zf> {
-///     fn zero_from(this: &'zf (dyn ExampleTrait<'a> + 'a)) -> ExampleTraitDynRef<'zf> {
-///         // This is safe because the trait object requires IsCovariant.
-///         ExampleTraitDynRef(unsafe { core::mem::transmute(this) })
-///     }
-/// }
-///
-/// // Implement ExampleTrait on the struct from the previous example
-/// # struct MyStruct<'a>(&'a str);
-/// # unsafe impl<'a> IsCovariant<'a> for MyStruct<'a> {}
-/// impl<'a> ExampleTrait<'a> for MyStruct<'a> {
-///     fn get_message(&self) -> &'a str {
-///         self.0
-///     }
-/// }
-///
-/// // Example usage: a Yoke of a trait object
-/// let s = "Hello World".to_string();
-/// let yoke: Yoke<ExampleTraitDynRef<'static>, Box<dyn ExampleTrait>> =
-///     Yoke::attach_to_zero_copy_cart(Box::new(MyStruct(&s)));
-///
-/// assert_eq!(yoke.get().0.get_message(), "Hello World");
-/// ```
-///
-/// [`Yoke`]: crate::Yoke
-/// [`Yokeable`]: crate::Yokeable
-/// [`ZeroFrom`]: crate::ZeroFrom
-pub unsafe trait IsCovariant<'a>: 'a {}
-
-// IsCovariant is implemented on the standard library Copy types in macro_impls.rs
-
-// The following impls are safe because there is only one lifetime, 'a, and 'a is covariant
-
-unsafe impl<'a> IsCovariant<'a> for () {}
-
-unsafe impl<'a> IsCovariant<'a> for str {}
-#[cfg(feature = "alloc")]
-unsafe impl<'a> IsCovariant<'a> for String {}
-
-unsafe impl<'a, T: IsCovariant<'a>> IsCovariant<'a> for Option<T> {}
-
-unsafe impl<'a, T1: IsCovariant<'a>, T2: IsCovariant<'a>> IsCovariant<'a> for (T1, T2) {}
-
-unsafe impl<'a, T: IsCovariant<'a>> IsCovariant<'a> for [T] {}
-
-unsafe impl<'a, T: IsCovariant<'a>, const N: usize> IsCovariant<'a> for [T; N] {}
-
-#[cfg(feature = "alloc")]
-unsafe impl<'a, T: IsCovariant<'a> + ?Sized> IsCovariant<'a> for Box<T> {}
-
-#[cfg(feature = "alloc")]
-unsafe impl<'a, T: IsCovariant<'a> + ?Sized> IsCovariant<'a> for Rc<T> {}
-
-// This is safe because T has a covariant lifetime, and Cow's lifetime is also covariant
-#[cfg(feature = "alloc")]
-unsafe impl<'a, T: IsCovariant<'a> + ToOwned + ?Sized> IsCovariant<'a> for Cow<'a, T> where
-    <T as ToOwned>::Owned: Sized
-{
-}
-
-// This is safe because T has a covariant lifetime, and the reference lifetime is also covariant
-unsafe impl<'a, T: IsCovariant<'a> + ?Sized> IsCovariant<'a> for &'a T {}