projects/linux·blob master · refs

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1// SPDX-License-Identifier: Apache-2.0 OR MIT
2
3//! Rust standard library vendored code.
4//!
5//! The contents of this file come from the Rust standard library, hosted in
6//! the <https://github.com/rust-lang/rust> repository, licensed under
7//! "Apache-2.0 OR MIT" and adapted for kernel use. For copyright details,
8//! see <https://github.com/rust-lang/rust/blob/master/COPYRIGHT>.
9
10use crate::sync::{arc::ArcInner, Arc};
11use core::any::Any;
12
13impl Arc<dyn Any + Send + Sync> {
14 /// Attempt to downcast the `Arc<dyn Any + Send + Sync>` to a concrete type.
15 pub fn downcast<T>(self) -> core::result::Result<Arc<T>, Self>
16 where
17 T: Any + Send + Sync,
18 {
19 if (*self).is::<T>() {
20 // SAFETY: We have just checked that the type is correct, so we can cast the pointer.
21 unsafe {
22 let ptr = self.ptr.cast::<ArcInner<T>>();
23 core::mem::forget(self);
24 Ok(Arc::from_inner(ptr))
25 }
26 } else {
27 Err(self)
28 }
29 }
30}