refactor(allocator): clean up obsolete bumpalo references (#18172)

## Summary

Now that bumpalo has been inlined into oxc_allocator (#18168), this PR cleans up comments and documentation that still reference bumpalo as an external dependency.

- Update module docs in `bump.rs` and `bumpalo_alloc.rs` to say "originally derived from" instead of "ported from"
- Remove obsolete comments about bumpalo version pinning in `from_raw_parts.rs`
- Update inline comments in `allocator.rs` from "delegates to bumpalo" to "it's a small function"
- Remove outdated TODO about replacing bumpalo in `tracking.rs`
- Update `ARCHITECTURE.md` and parser docs to reference `oxc_allocator` instead of bumpalo
- Clean up bumpalo references in other crates (`oxc_semantic`, `oxc_data_structures`, `apps/oxlint`, `napi/parser`, `tasks/ast_tools`)

## Test plan

- [x] `cargo check -p oxc_allocator` passes
- [x] `cargo test -p oxc_allocator` passes
- [x] Changes are documentation/comment only - no functional changes

🤖 Generated with [Claude Code](https://claude.ai/code)

ARCHITECTURE.md

@@ -227,7 +227,7 @@ Source Text → Arena Allocator → AST Nodes → Visitors → Results
 
 #### Parser Performance Implementation
 
-- AST is allocated in a memory arena ([bumpalo](https://crates.io/crates/bumpalo)) for fast AST memory allocation and deallocation
+- AST is allocated in a memory arena (oxc_allocator) for fast AST memory allocation and deallocation
 - Short strings are inlined by [CompactString](https://crates.io/crates/compact_str)
 - No other heap allocations are done except the above two
 - Scope binding, symbol resolution and some syntax errors are not done in the parser, they are delegated to the semantic analyzer

apps/oxlint/src/js_plugins/external_linter.rs

@@ -147,8 +147,7 @@ fn wrap_lint_file(cb: JsLintFileCb) -> ExternalLinterLintFileCb {
             // `AllocatorPool::new_fixed_size`, so all `Allocator`s are created via `FixedSizeAllocator`.
             // This is somewhat sketchy, as we don't have a type-level guarantee of this invariant,
             // but it does hold at present.
-            // When we replace `bumpalo` with a custom allocator, we can close this soundness hole.
-            // TODO: Do that.
+            // TODO: Close this soundness hole with type-level guarantees.
             let (buffer_id, buffer) = unsafe { get_buffer(allocator) };
 
             // Send data to JS

apps/oxlint/src/js_plugins/parse.rs

@@ -118,7 +118,7 @@ unsafe fn parse_raw_impl(
     // Get offsets and size of data region to be managed by arena allocator.
     // Leave space for source before it, and space for metadata after it.
     // Metadata actually only takes 5 bytes, but round everything up to multiple of 16,
-    // as `bumpalo` requires that alignment.
+    // as the arena allocator requires that alignment.
     const RAW_METADATA_SIZE: usize = size_of::<RawTransferMetadata>();
     const {
         assert!(RAW_METADATA_SIZE >= BUMP_ALIGN);

apps/oxlint/src/js_plugins/raw_fs.rs

@@ -17,9 +17,9 @@ use oxc_linter::RuntimeFileSystem;
 /// Must only be used in conjunction with `AllocatorPool` created with `new_fixed_size`,
 /// which wraps `Allocator`s with a custom `Drop` impl, which makes `read_to_arena_str` safe.
 ///
-/// This is a temporary solution. When we replace `bumpalo` with our own allocator, all strings
-/// will be written at start of the arena, so then `OsFileSystem` will work fine, and we can
-/// remove `RawTransferFileSystem`. TODO: Do that!
+/// This is a temporary solution. All strings should be written at start of the arena,
+/// so then `OsFileSystem` would work fine, and we can remove `RawTransferFileSystem`.
+/// TODO: Do that!
 pub struct RawTransferFileSystem;
 
 impl RuntimeFileSystem for RawTransferFileSystem {

crates/oxc_allocator/src/allocator.rs

@@ -253,7 +253,7 @@ impl Allocator {
     /// [`Vec::new_in`]: crate::Vec::new_in
     /// [`HashMap::new_in`]: crate::HashMap::new_in
     //
-    // `#[inline(always)]` because just delegates to `bumpalo` method
+    // `#[inline(always)]` because it's a small function
     #[expect(clippy::inline_always)]
     #[inline(always)]
     pub fn new() -> Self {
@@ -268,7 +268,7 @@ impl Allocator {
     ///
     /// See [`Allocator`] docs for more information on efficient use of [`Allocator`].
     //
-    // `#[inline(always)]` because just delegates to `bumpalo` method
+    // `#[inline(always)]` because it's a small function
     #[expect(clippy::inline_always)]
     #[inline(always)]
     pub fn with_capacity(capacity: usize) -> Self {
@@ -506,7 +506,7 @@ impl Allocator {
     /// }
     /// ```
     //
-    // `#[inline(always)]` because it just delegates to `bumpalo`
+    // `#[inline(always)]` because it's a small function
     #[expect(clippy::inline_always)]
     #[inline(always)]
     pub fn reset(&mut self) {
@@ -536,7 +536,7 @@ impl Allocator {
     ///
     /// [`used_bytes`]: Allocator::used_bytes
     //
-    // `#[inline(always)]` because it just delegates to `bumpalo`
+    // `#[inline(always)]` because it's a small function
     #[expect(clippy::inline_always)]
     #[inline(always)]
     pub fn capacity(&self) -> usize {
@@ -616,7 +616,7 @@ impl Allocator {
     /// Get inner [`Bump`].
     ///
     /// This method is not public. We don't want to expose `Bump` to user.
-    /// The fact that we're using `bumpalo` is an internal implementation detail.
+    /// The inner `Bump` is an internal implementation detail.
     //
     // `#[inline(always)]` because it's a no-op
     #[expect(clippy::inline_always)]

crates/oxc_allocator/src/bump.rs

@@ -1,6 +1,6 @@
-//! Bumpalo arena allocator, ported from <https://github.com/fitzgen/bumpalo>
+//! Arena allocator.
 //!
-//! This module is ported exactly from bumpalo v3.19.0 without modifications.
+//! This module was originally derived from bumpalo v3.19.0.
 
 #![allow(
     clippy::borrow_as_ptr,
@@ -40,7 +40,7 @@
     unsafe_op_in_unsafe_fn
 )]
 
-//! Bumpalo arena allocator, ported from <https://github.com/fitzgen/bumpalo>
+//! Arena allocator.
 
 #[doc(hidden)]
 pub extern crate alloc as core_alloc;

crates/oxc_allocator/src/bumpalo_alloc.rs

@@ -8,9 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-//! Memory allocation APIs, ported from bumpalo.
+//! Memory allocation APIs.
 //!
-//! This module is ported exactly from bumpalo without modifications.
+//! This module was originally derived from bumpalo and Rust's allocator APIs.
 
 #![allow(
     clippy::collapsible_if,

crates/oxc_allocator/src/from_raw_parts.rs

@@ -17,7 +17,7 @@ use std::{
 
 use crate::{Allocator, bump::Bump};
 
-/// Minimum alignment for allocator chunks. This is hard-coded on `bumpalo`.
+/// Minimum alignment for allocator chunks.
 const MIN_ALIGN: usize = 16;
 
 const CHUNK_FOOTER_SIZE: usize = size_of::<ChunkFooter>();
@@ -35,12 +35,8 @@ impl Allocator {
 
     /// Construct a static-sized [`Allocator`] from an existing memory allocation.
     ///
-    /// **IMPORTANT: WE MUST NOT CHANGE THE VERSION OF BUMPALO DEPENDENCY**.
-    ///
-    /// This code only remains sound as long as the code in version of `bumpalo` we're using matches
-    /// the duplicate of `bumpalo`'s internals contained in this file.
-    ///
-    /// `bumpalo` is pinned to version `=3.19.0` in `Cargo.toml`.
+    /// This code relies on specific internal layout of the arena allocator.
+    /// Changes to `Bump` internals may break this code.
     ///
     /// The [`Allocator`] which is returned takes ownership of the memory allocation,
     /// and the allocation will be freed if the `Allocator` is dropped.
@@ -48,9 +44,6 @@ impl Allocator {
     ///
     /// The [`Allocator`] returned by this function cannot grow.
     ///
-    /// This hack is all very inadvisable!
-    /// Only implemented as a temporary stopgap until we replace `bumpalo` with our own allocator.
-    ///
     /// # SAFETY
     ///
     /// * `ptr` must be aligned on [`RAW_MIN_ALIGN`].
@@ -61,7 +54,7 @@ impl Allocator {
     ///
     /// # Panics
     ///
-    /// Panics if cannot determine layout of Bumpalo's `Bump` type, or on a big endian system.
+    /// Panics if cannot determine layout of `Bump` type, or on a big endian system.
     ///
     /// [`RAW_MIN_ALIGN`]: Self::RAW_MIN_ALIGN
     /// [`RAW_MIN_SIZE`]: Self::RAW_MIN_SIZE
@@ -128,7 +121,7 @@ impl Allocator {
     ///
     /// Returns a pointer to the start of an uninitialized section of `bytes` bytes.
     ///
-    /// Note: [`alloc_layout`] allocates at *end* of the current chunk, because `bumpalo` bumps downwards,
+    /// Note: [`alloc_layout`] allocates at *end* of the current chunk, because the arena allocator bumps downwards,
     /// hence the need for this method, to allocate at *start* of current chunk.
     ///
     /// This method is dangerous, and should not ordinarily be used.
@@ -343,10 +336,7 @@ impl Allocator {
 
 /// Allocator chunk footer.
 ///
-/// Copied exactly from `bumpalo` v3.19.0.
-///
-/// This type is not exposed by `bumpalo` crate, but the type is `#[repr(C)]`, so we can rely on our
-/// duplicate here having the same layout, as long as we don't change the version of `bumpalo` we use.
+/// This type must match the layout of `ChunkFooter` in `bump.rs`.
 #[repr(C)]
 #[derive(Debug)]
 struct ChunkFooter {

crates/oxc_allocator/src/pool/fixed_size.rs

@@ -331,7 +331,7 @@ const ALLOC_LAYOUT: Layout = match Layout::from_size_align(ALLOC_SIZE, ALLOC_ALI
 ///
 ///                                                         ALLOCATOR
 /// <----------------------------------------->             `Allocator` chunk (`CHUNK_SIZE` bytes)
-///                                      <---->             Bumpalo's `ChunkFooter` (aligned on 16)
+///                                      <---->             `ChunkFooter` (aligned on 16)
 /// <----------------------------------->                   `Allocator` chunk data storage (for AST)
 ///
 ///                                                         METADATA
@@ -345,8 +345,8 @@ const ALLOC_LAYOUT: Layout = match Layout::from_size_align(ALLOC_SIZE, ALLOC_ALI
 /// Note that the buffer sent to JS includes both the `Allocator` chunk, and `RawTransferMetadata`,
 /// but does NOT include `FixedSizeAllocatorMetadata`.
 ///
-/// The end of the region used for `Allocator` chunk must be aligned on `Allocator::RAW_MIN_ALIGN` (16),
-/// due to the requirements of Bumpalo. We manage that by:
+/// The end of the region used for `Allocator` chunk must be aligned on `Allocator::RAW_MIN_ALIGN` (16).
+/// We manage that by:
 /// * `BLOCK_SIZE` is a multiple of 16.
 /// * `RawTransferMetadata` is 16 bytes.
 /// * Size of `FixedSizeAllocatorMetadata` is rounded up to a multiple of 16.

crates/oxc_allocator/src/tracking.rs

@@ -13,8 +13,7 @@
 //! The 2nd cargo feature `disable_track_allocations` is to ensure that compiling with `--all-features`
 //! will not load this module.
 //!
-//! As soon as we replace `bumpalo` with our own arena allocator, we'll remove the hack from `get_stats_ref`,
-//! and make this sound.
+//! TODO: Remove the hack from `get_stats_ref` and make this sound.
 
 use std::{cell::Cell, ptr};
 

crates/oxc_allocator/src/vec2/mod.rs

@@ -1,4 +1,5 @@
-// This file is copied from the [Bumpalo's Vec](https://github.com/fitzgen/bumpalo/blob/1d2fbea9e3d0c2be56367b9ad5382ff33852a188/src/collections/vec.rs)
+// This file was originally derived from Bumpalo's Vec:
+// https://github.com/fitzgen/bumpalo/blob/1d2fbea9e3d0c2be56367b9ad5382ff33852a188/src/collections/vec.rs
 
 // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at

crates/oxc_allocator/src/vec2/raw_vec.rs

@@ -1,4 +1,5 @@
-// This file is copied from the [Bumpalo's Vec](https://github.com/fitzgen/bumpalo/blob/1d2fbea9e3d0c2be56367b9ad5382ff33852a188/src/collections/raw_vec.rs)
+// This file was originally derived from Bumpalo's Vec:
+// https://github.com/fitzgen/bumpalo/blob/1d2fbea9e3d0c2be56367b9ad5382ff33852a188/src/collections/raw_vec.rs
 
 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
 // file at the top-level directory of this distribution and at

crates/oxc_data_structures/src/stack/non_empty.rs

@@ -58,7 +58,7 @@ use super::{StackCapacity, StackCommon};
 ///    uses 1 less register, but disadvantage that [`last`] and [`last_mut`] are 2 instructions, not 1.
 ///    <https://godbolt.org/z/xnx7YP5de>
 ///
-/// 2. Stack could grow downwards, like `bumpalo` allocator does. This would probably make [`pop`] use
+/// 2. Stack could grow downwards, like a bump allocator does. This would probably make [`pop`] use
 ///    1 less register, but at the cost that: (a) the stack can never grow in place, which would incur
 ///    more memory copies when the stack grows, and (b) [`as_slice`] would have the entries in
 ///    reverse order.

crates/oxc_parser/src/lib.rs

@@ -22,7 +22,7 @@
 //! # Performance
 //!
 //! The following optimization techniques are used:
-//! * AST is allocated in a memory arena ([bumpalo](https://docs.rs/bumpalo)) for fast AST drop
+//! * AST is allocated in a memory arena ([oxc_allocator](https://docs.rs/oxc_allocator)) for fast AST drop
 //! * [`oxc_span::Span`] offsets uses `u32` instead of `usize`
 //! * Scope binding, symbol resolution and complicated syntax errors are not done in the parser,
 //! they are delegated to the [semantic analyzer](https://docs.rs/oxc_semantic)

crates/oxc_semantic/src/node/mod.rs

@@ -11,7 +11,7 @@ use oxc_syntax::{node::NodeId, scope::ScopeId};
 #[derive(Debug, Clone, Copy)]
 pub struct AstNode<'a> {
     id: NodeId,
-    /// A pointer to the ast node, which resides in the `bumpalo` memory arena.
+    /// A pointer to the ast node, which resides in the memory arena.
     kind: AstKind<'a>,
 
     /// Associated Scope (initialized by binding)

napi/parser/src/raw_transfer.rs

@@ -183,7 +183,7 @@ unsafe fn parse_raw_impl(
     // Get offsets and size of data region to be managed by arena allocator.
     // Leave space for source before it, and space for metadata after it.
     // Metadata actually only takes 5 bytes, but round everything up to multiple of 16,
-    // as `bumpalo` requires that alignment.
+    // as the arena allocator requires that alignment.
     const RAW_METADATA_SIZE: usize = size_of::<RawTransferMetadata>();
     const {
         assert!(RAW_METADATA_SIZE >= BUMP_ALIGN);

tasks/ast_tools/src/generators/raw_transfer.rs

@@ -49,7 +49,7 @@ const ALLOCATOR_CHUNK_END_ALIGN: u32 = 16;
 /// This size includes metadata stored after the `Allocator` chunk which contains AST data.
 ///
 /// Must be a multiple of [`ALLOCATOR_CHUNK_END_ALIGN`].
-/// 16 bytes less than 2 GiB, to allow 16 bytes for `malloc` metadata (like Bumpalo does).
+/// 16 bytes less than 2 GiB, to allow 16 bytes for `malloc` metadata.
 const BLOCK_SIZE: u32 = (1 << 31) - MALLOC_RESERVED_SIZE; // 2 GiB - 16 bytes
 const _: () = assert!(BLOCK_SIZE.is_multiple_of(ALLOCATOR_CHUNK_END_ALIGN));