feat(allocator): add HashSet

[sapphi-red]

Adds the arena-allocated HashSet.

[sapphi-red]

• feat(allocator): add HashSet #14212 : 2 dependent PRs (#14079 , #14314 ) 👈 (View in Graphite)
• feat(allocator): add HashMap::from_iter_in #14211
• main

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #14212 will not alter performance

_{Comparing 09-28-feat-allocator-add-hashset (f37b211) with main (0c14e50)}

Summary

✅ 37 untouched

[overlookmotel]

Are the implementations of the various methods copied from hashbrown?

[sapphi-red]

Are the implementations of the various methods copied from hashbrown?

Probably it was.

The AI generated the code as a wrapper around HashMap. But while checking the implementation, I found that it is easier to implement as a wrapper around hashbrown::HashSet (because then we can utilize Deref). So I've rewritten the implementation.

[Copilot]

Pull Request Overview

This PR adds a new arena-allocated HashSet type to the oxc_allocator crate, matching the existing HashMap implementation. The HashSet is designed to work with the arena allocator and prevents Drop types from being stored to avoid memory leaks.

• Implements HashSet as a thin wrapper around hashbrown::HashSet with disabled Drop
• Adds comprehensive API including constructors, iterators, and trait implementations
• Establishes conversion between HashMap<T, ()> and HashSet<T>

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
crates/oxc_allocator/src/lib.rs	Adds module declaration and public export for the new HashSet type
crates/oxc_allocator/src/hash_set.rs	Complete implementation of arena-allocated HashSet with safety checks and API methods
crates/oxc_allocator/src/hash_map.rs	Makes HashMap's inner field public(crate) and removes commented conversion code

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[overlookmotel]

Thanks for doing this (and for including the oddity of allocator method).

To save time, in place of review, I've pushed a few commits with suggested changes (all minor). @sapphi-red If you're happy with them, please go ahead and merge, or feel free to make further changes if you don't like them.

[graphite-app]

Merge activity

• Oct 4, 11:13 AM UTC: sapphi-red added this pull request to the Graphite merge queue.
• Oct 4, 11:19 AM UTC: Merged by the Graphite merge queue.