diff options
Diffstat (limited to 'library/core/src/any.rs')
-rw-r--r-- | library/core/src/any.rs | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/library/core/src/any.rs b/library/core/src/any.rs index 7969f4055..09f52d692 100644 --- a/library/core/src/any.rs +++ b/library/core/src/any.rs @@ -153,6 +153,7 @@ #![stable(feature = "rust1", since = "1.0.0")] use crate::fmt; +use crate::hash; use crate::intrinsics; /////////////////////////////////////////////////////////////////////////////// @@ -662,10 +663,10 @@ impl dyn Any + Send + Sync { /// While `TypeId` implements `Hash`, `PartialOrd`, and `Ord`, it is worth /// noting that the hashes and ordering will vary between Rust releases. Beware /// of relying on them inside of your code! -#[derive(Clone, Copy, Debug, Hash, Eq, PartialOrd, Ord)] +#[derive(Clone, Copy, Debug, Eq, PartialOrd, Ord)] #[stable(feature = "rust1", since = "1.0.0")] pub struct TypeId { - t: u64, + t: u128, } #[stable(feature = "rust1", since = "1.0.0")] @@ -696,7 +697,31 @@ impl TypeId { #[stable(feature = "rust1", since = "1.0.0")] #[rustc_const_unstable(feature = "const_type_id", issue = "77125")] pub const fn of<T: ?Sized + 'static>() -> TypeId { - TypeId { t: intrinsics::type_id::<T>() } + #[cfg(bootstrap)] + let t = intrinsics::type_id::<T>() as u128; + #[cfg(not(bootstrap))] + let t: u128 = intrinsics::type_id::<T>(); + TypeId { t } + } +} + +#[stable(feature = "rust1", since = "1.0.0")] +impl hash::Hash for TypeId { + #[inline] + fn hash<H: hash::Hasher>(&self, state: &mut H) { + // We only hash the lower 64 bits of our (128 bit) internal numeric ID, + // because: + // - The hashing algorithm which backs `TypeId` is expected to be + // unbiased and high quality, meaning further mixing would be somewhat + // redundant compared to choosing (the lower) 64 bits arbitrarily. + // - `Hasher::finish` returns a u64 anyway, so the extra entropy we'd + // get from hashing the full value would probably not be useful + // (especially given the previous point about the lower 64 bits being + // high quality on their own). + // - It is correct to do so -- only hashing a subset of `self` is still + // with an `Eq` implementation that considers the entire value, as + // ours does. + (self.t as u64).hash(state); } } |