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Merged
merged 2 commits into from
Oct 4, 2025
Merged

remove Base.memhash global #59697

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c3350a0
remove Base.memhash global
vtjnash Sep 30, 2025
7033f56
Update NEWS.md
vtjnash Oct 3, 2025
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4 changes: 3 additions & 1 deletion NEWS.md
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Expand Up @@ -17,7 +17,9 @@ Language changes
* `mod(x::AbstractFloat, -Inf)` now returns `x` (as long as `x` is finite), this aligns with C standard and
is considered a bug fix ([#47102])

- The `hash` algorithm and its values have changed. Most `hash` specializations will remain correct and require no action. Types that reimplement the core hashing logic independently, such as some third-party string packages do, may require a migration to the new algorithm. ([#57509])
* The `hash` algorithm and its values have changed for certain types, most notably AbstractString. Any `hash` specializations for equal types to those that changed, such as some third-party string packages, may need to be deleted. ([#57509], [#59691])

* The `hash(::AbstractString)` function is now a zero-copy / zero-cost function, based upon providing a correct implementation of the `codeunit` and `iterate` functions. Third-party string packages should migrate to the new algorithm by deleting their existing overrides of the `hash` function. ([#59691])

* Indexless `getindex` and `setindex!` (i.e. `A[]`) on `ReinterpretArray` now correctly throw a `BoundsError` when there is more than one element. ([#58814])

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4 changes: 0 additions & 4 deletions base/hashing.jl
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Expand Up @@ -629,7 +629,3 @@ hash(data::AbstractString, h::UInt) =
hash_bytes(utf8units(data), UInt64(h), HASH_SECRET) % UInt
@assume_effects :total hash(data::String, h::UInt) =
GC.@preserve data hash_bytes(pointer(data), sizeof(data), UInt64(h), HASH_SECRET) % UInt

# no longer used in Base, but a lot of packages access these internals
const memhash = UInt === UInt64 ? :memhash_seed : :memhash32_seed
const memhash_seed = UInt === UInt64 ? 0x71e729fd56419c81 : 0x56419c81