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| -rw-r--r-- | src/libcore/any.rs | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/src/libcore/any.rs b/src/libcore/any.rs index a2aa6b3fea5..5126fe01a3f 100644 --- a/src/libcore/any.rs +++ b/src/libcore/any.rs @@ -74,6 +74,16 @@ use crate::intrinsics; /// See the [module-level documentation][mod] for more details. /// /// [mod]: index.html +// This trait is not unsafe, though we rely on the specifics of it's sole impl's +// `type_id` function in unsafe code (e.g., `downcast`). Normally, that would be +// a problem, but because the only impl of `Any` is a blanket implementation, no +// other code can implement `Any`. +// +// We could plausibly make this trait unsafe -- it would not cause breakage, +// since we control all the implementations -- but we choose not to as that's +// both not really necessary and may confuse users about the distinction of +// unsafe traits and unsafe methods (i.e., `type_id` would still be safe to call, +// but we would likely want to indicate as such in documentation). #[stable(feature = "rust1", since = "1.0.0")] pub trait Any: 'static { /// Gets the `TypeId` of `self`. |