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| -rw-r--r-- | src/doc/unstable-book/src/language-features/trait-upcasting.md | 26 |
1 files changed, 0 insertions, 26 deletions
diff --git a/src/doc/unstable-book/src/language-features/trait-upcasting.md b/src/doc/unstable-book/src/language-features/trait-upcasting.md deleted file mode 100644 index a5f99cc86f2..00000000000 --- a/src/doc/unstable-book/src/language-features/trait-upcasting.md +++ /dev/null @@ -1,26 +0,0 @@ -# `trait_upcasting` - -The tracking issue for this feature is: [#65991] - -[#65991]: https://github.com/rust-lang/rust/issues/65991 - ------------------------- - -The `trait_upcasting` feature adds support for trait upcasting coercion. This allows a -trait object of type `dyn Bar` to be cast to a trait object of type `dyn Foo` -so long as `Bar: Foo`. - -```rust,edition2018 -#![feature(trait_upcasting)] - -trait Foo {} - -trait Bar: Foo {} - -impl Foo for i32 {} - -impl<T: Foo + ?Sized> Bar for T {} - -let bar: &dyn Bar = &123; -let foo: &dyn Foo = bar; -``` |