refactor(allocator): inline bumpalo into oxc_allocator

[Boshen]

Summary

• Port bumpalo v3.19.0 directly into oxc_allocator as internal modules
• Add bump.rs with the Bump allocator implementation
• Add bumpalo_alloc.rs with the Alloc trait and related types
• Update all imports to use internal crate::bump::Bump
• Remove bumpalo dependency from workspace and crate

This gives us full control over the arena allocator implementation for future optimizations. The ported code is kept exactly as-is from bumpalo with lint allows added to preserve the original implementation.

Test plan

• cargo test -p oxc_allocator - all 26 unit tests pass
• cargo clippy -p oxc_allocator --all-features - no warnings

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR inlines the bumpalo v3.19.0 bump allocator directly into oxc_allocator to gain full control over the arena allocator implementation for future optimizations. The ported code is kept exactly as-is with lint allows added to preserve the original implementation.

Changes:

• Adds bump.rs and bumpalo_alloc.rs modules with the complete bump allocator implementation from bumpalo v3.19.0
• Updates all imports across the crate to use crate::bump::Bump instead of bumpalo::Bump
• Removes the bumpalo dependency from workspace and crate-level Cargo.toml files

Reviewed changes

Copilot reviewed 14 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/oxc_allocator/src/bump.rs	Ports the main Bump allocator implementation with ~2067 lines including tests
crates/oxc_allocator/src/bumpalo_alloc.rs	Ports the Alloc trait and related memory allocation types (~800 lines)
crates/oxc_allocator/src/lib.rs	Declares the new internal modules as pub(crate)
crates/oxc_allocator/src/allocator.rs	Updates import from external bumpalo to internal bump module
crates/oxc_allocator/src/alloc.rs	Updates import and uses qualified method calls to avoid ambiguity
crates/oxc_allocator/src/allocator_api2.rs	Updates comments and uses qualified method calls for clarity
crates/oxc_allocator/src/vec.rs	Updates import to use internal bump module
crates/oxc_allocator/src/tracking.rs	Updates import to use internal bump module
crates/oxc_allocator/src/hash_map.rs	Updates import to use internal bump module
crates/oxc_allocator/src/hash_set.rs	Updates import to use internal bump module
crates/oxc_allocator/src/from_raw_parts.rs	Updates import and replaces Bump::<1>::with_min_align() with Bump::new()
crates/oxc_allocator/src/vec2/raw_vec.rs	Updates test import to use internal bump module
crates/oxc_allocator/Cargo.toml	Removes bumpalo dependency
Cargo.toml	Removes bumpalo dependency with explanatory comment
Cargo.lock	Updates dependency tree (bumpalo still present for wasm-bindgen)

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[codspeed-hq]

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing refactor/inline-bumpalo (5e07770) with main (38e4b53)}

Summary

✅ 42 untouched benchmarks
⏩ 3 skipped benchmarks¹

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Boshen]

Merge activity

• Jan 18, 7:20 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Jan 18, 7:21 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Jan 18, 7:27 AM UTC: Merged by the Graphite merge queue.