perf(formatter): avoid arena copy for borrowed string-literal text by hyf0 · Pull Request #23465 · oxc-project/oxc

hyf0 · 2026-06-16T02:02:51Z

What & why

Every formatted string literal flows through CleanedStringLiteralText::fmt, which copied the text
into the formatter arena unconditionally:

text(f.allocator().alloc_str(&self.text)).fmt(f);

self.text is a Cow<'a, str>, and in the common case — the literal already uses the preferred quote
style and needs no escape normalization — normalize_text returns Cow::Borrowed, a slice of the
source text that already has the 'a lifetime FormatElement::Text requires. So the alloc_str copy
is redundant for borrowed text. Pass the borrowed slice straight through and only allocate for the
owned (normalized) case:

let text_str: &'a str = match &self.text {
    Cow::Borrowed(borrowed) => borrowed,
    Cow::Owned(owned) => f.allocator().alloc_str(owned),
};
text(text_str).fmt(f);

This removes one arena allocation + memcpy per borrowed string literal and avoids duplicating the
literal's bytes into the arena (the source text already holds them). It is never more work than before:
the borrowed arm skips the allocation; the owned arm is unchanged (the added match just replaces the
implicit Cow deref the old code already performed).

Memory reduction (arena allocations)

Measured with cargo allocs (TestFiles::complicated). Only the arena-allocation count drops —
system allocations, reallocs, and arena reallocs are all unchanged:

file	arena allocs: before → after	reduction
antd.js	2,638,108 → 2,589,031	−49,077 (−1.86%)
pdf.mjs	442,227 → 440,620	−1,607 (−0.36%)
checker.ts	1,082,132 → 1,081,176	−956 (−0.09%)
App.tsx	214,178 → 213,475	−703 (−0.33%)
kitchen-sink.tsx	572,286 → 571,980	−306 (−0.05%)
binder.ts	63,981 → 63,948	−33 (−0.05%)
RadixUIAdoptionSection.jsx	1,172 → 1,149	−23 (−1.96%)

Raw allocs_formatter.snap diff (updated in this PR)

 File                       | File size      || Sys allocs     | Sys reallocs   || Arena allocs   | Arena reallocs
 ---------------------------------------------------------------------------------------------------------------------------
-checker.ts                 | 2.92 MB        ||          18642 |            565 ||        1082132 |         118667
+checker.ts                 | 2.92 MB        ||          18642 |            565 ||        1081176 |         118667

-App.tsx                    | 415.34 kB      ||           7588 |            172 ||         214178 |          25343
+App.tsx                    | 415.34 kB      ||           7588 |            172 ||         213475 |          25343

-RadixUIAdoptionSection.jsx | 2.52 kB        ||             54 |             28 ||           1172 |            157
+RadixUIAdoptionSection.jsx | 2.52 kB        ||             54 |             28 ||           1149 |            157

-pdf.mjs                    | 567.30 kB      ||          15308 |            342 ||         442227 |          43489
+pdf.mjs                    | 567.30 kB      ||          15308 |            342 ||         440620 |          43489

-antd.js                    | 6.69 MB        ||          83239 |           4652 ||        2638108 |         302458
+antd.js                    | 6.69 MB        ||          83239 |           4652 ||        2589031 |         302458

-binder.ts                  | 193.08 kB      ||            824 |             43 ||          63981 |           6932
+binder.ts                  | 193.08 kB      ||            824 |             43 ||          63948 |           6932

-kitchen-sink.tsx           | 732.90 kB      ||          20458 |           3156 ||         572286 |          60147
+kitchen-sink.tsx           | 732.90 kB      ||          20458 |           3156 ||         571980 |          60147

Instruction count (CodSpeed) is neutral, as expected: arena bump-allocation is cheap on the CPU, so
removing the copies reduces memory/allocations without materially changing instructions. This is a
memory optimization, not a speed one.

Behavior-preserving

The same bytes reach text() in both arms. cargo test -p oxc_formatter and the prettier conformance
suite pass with byte-identical output (no snapshot churn).

Prepared with AI assistance (automated performance loop) and validated against local allocation
snapshots, benchmarks, and the prettier conformance suite; opened as a draft.

codspeed-hq · 2026-06-16T02:07:06Z

Merging this PR will not alter performance

✅ 52 untouched benchmarks
⏩ 19 skipped benchmarks¹

_{Comparing hyf0:perf/formatter-cleaned-string-borrowed-passthrough (9576364) with main (09762d9)}

19 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. ↩

leaysgur

Thank you~! 👍🏻

…usable alloc_cow_str Adds Allocator::alloc_cow_str(cow): returns a Cow's &str without copying when Cow::Borrowed, copying into the arena only for Cow::Owned. Crystallizes the borrow-passthrough pattern (string oxc-project#23465, number oxc-project#23512, bigint) into one documented, reusable helper instead of an inline match repeated at each site. Migrates the in-tree sites to it: oxc_formatter numeric + bigint literals, and oxc_formatter_json::arena_cow_str (previously a local copy of the same pattern). Behaviour- and allocation-neutral (pure consolidation); allocs snapshots unchanged.

…usable alloc_cow_str Adds Allocator::alloc_cow_str(&cow): returns a Cow's &str without copying when Cow::Borrowed, copying into the arena only for Cow::Owned. Crystallizes the borrow-passthrough pattern (string oxc-project#23465, number oxc-project#23512, bigint oxc-project#23534) into one documented, reusable helper instead of the inline match repeated at each site. Takes the Cow by shared reference so it also works where the Cow lives behind a &self borrow (string literals) and can't be moved out. Migrates every in-tree site to it: - oxc_formatter string / numeric / bigint literals - oxc_formatter_json: removes the crate-local arena_cow_str wrapper; call sites now use the shared helper directly (f.allocator().alloc_cow_str(&cow)), matching how the formatters already call f.allocator().alloc_str(...) directly with no per-crate wrapper. Behaviour- and allocation-neutral (pure consolidation); allocs snapshots unchanged.

…ls (#23534) ## What `BigIntLiteral` formatting previously **always** copied the literal text into the arena via `alloc_str`, even though the common case — an already-lowercase bigint such as `123n` — needs no change. This borrows the source slice straight through and copies into the arena only when the literal actually contains uppercase hex digits (e.g. `0xFFn`). Mirrors the borrow-passthrough already used for string literals (#23465) and numeric literals (#23512). ## Δ `allocs_formatter.snap` (arena bytes): **kitchen-sink.tsx −39**. No regression on any fixture; allocation *count* unchanged. Output is byte-identical (prettier-conformance snapshots unchanged). Prepared with AI assistance.

…usable alloc_cow_str Adds Allocator::alloc_cow_str(&cow): returns a Cow's &str without copying when Cow::Borrowed, copying into the arena only for Cow::Owned. Crystallizes the borrow-passthrough pattern (string oxc-project#23465, number oxc-project#23512, bigint oxc-project#23534) into one documented, reusable helper instead of the inline match repeated at each site. Takes the Cow by shared reference so it also works where the Cow lives behind a &self borrow (string literals) and can't be moved out. Migrates every in-tree site to it: - oxc_formatter string / numeric / bigint literals - oxc_formatter_json: removes the crate-local arena_cow_str wrapper; call sites now use the shared helper directly (f.allocator().alloc_cow_str(&cow)), matching how the formatters already call f.allocator().alloc_str(...) directly with no per-crate wrapper. Behaviour- and allocation-neutral (pure consolidation); allocs snapshots unchanged.

# Oxlint ### 💥 BREAKING CHANGES - 36009dd allocator: [**BREAKING**] `GetAllocator::allocator` take `&self` (#23676) (overlookmotel) ### 🚀 Features - ff65285 linter: `no-restricted-globals` add missing upstream options (#23663) (Sysix) - 7b8bd89 linter/typescript: Implement suggestion for `no-unnecessary-type-constraint` rule (#23646) (Mikhail Baev) - 0dc2405 linter: Add schema for `eslint/no-restricted-properties` (#23619) (Sysix) - b638d0e linter: Add schema for `node/callback-return` (#23615) (Sysix) - eb8bedc linter: Add schema for `import/extensions` (#23557) (WaterWhisperer) - 46f3625 linter: Implement node/no-sync rule (#23589) (fujitani sora) - b01739a linter: Add schema for `unicorn/numeric-separators-style` (#23554) (Mikhail Baev) - 68afd2a linter/node: Implement `no-mixed-requires` rule (#23539) (fujitani sora) - 59d8893 linter: `unicorn/numeric-separators-style` support missing options (#23524) (Sysix) - a421215 linter: Add schema for `eslint/prefer-destructuring` (#23410) (WaterWhisperer) - 84438be linter/jsdoc: Added missing options to `require-param-description` (#23416) (kapobajza) - c145b72 linter/jsdoc/require-param-type: Implement fixer (#23513) (camc314) - 51910df linter/jsdoc: Add missing options to `require-param-type` rule (#23418) (kapobajza) - e90925f linter/unicorn: Implement prefer-number-coercion rule (#23497) (Shekhu☺️) - dd1c866 linter/vue: Implement no-async-in-computed-properties rule (#23493) (bab) - b02444e linter: Add schema for `react/jsx-no-script-url` (#23475) (WaterWhisperer) - 53509a8 minifier: Treeshake pure typed arrays and Set/Map array literals (#23469) (Dunqing) - a8dce46 linter/unicorn: Implement `max-nested-calls` rule (#23461) (arieleli01212) ### 🐛 Bug Fixes - b1948a1 linter/radix: Avoid panic on `parseInt` with a spread radix argument (#23623) (Jerry Zhao) - f28ccfd linter/prefer-query-selector: Use a compound selector for multiple classes (#23628) (Jerry Zhao) - 13f2970 linter/prefer-numeric-literals: Avoid panic on `parseInt` with a spread radix argument (#23624) (Jerry Zhao) - 57612b3 linter: Report invalid capitalized-comments ignore patterns (#23608) (camc314) - 800ee2a linter/consistent-vitest-vi: Preserve import aliases when rewriting the import (#23568) (Yunfei He) - f78b5e1 linter/consistent-indexed-object-style: Don't leak a stray comma into the value type (#23566) (Yunfei He) - 6b104e8 linter/radix: Detect a trailing comma only after the argument (#23569) (Yunfei He) - 2de20cb linter/unicorn/prefer-at: Correct two-argument `slice().pop()` index (#23565) (Yunfei He) - de778ec linter: `unicorn/numeric-separators-style` preserve dot for floats without decial part (#23553) (Sysix) - 651027c linter/curly: Remove only the block's own braces (#23580) (Yunfei He) - 687e835 linter/array-type: Parenthesize a conditional-type element (#23579) (Yunfei He) - 9c80dff linter/unicorn/no-unnecessary-await: Don't paste operators into invalid syntax (#23556) (Yunfei He) - 46e1463 linter/no-compare-neg-zero: Delete the `-` of a parenthesized `-0` (#23578) (Yunfei He) - d172a97 linter/unicorn/prefer-math-trunk: Skip fixer for LHS with side effects (#23548) (camc314) - 1c3a9bd linter/unicorn/prefer-negative-index: Don't report `Array#with` (#23518) (Yunfei He) - c17db5d linter/unicorn/prefer-spread: Don't report `.slice()` on non-array receivers (#23520) (Yunfei He) - 9cd0c2f linter/unicorn/prefer-date-now: Keep `BigInt` wrapper when fixing `BigInt(new Date())` (#23523) (Yunfei He) - 16bb890 linter/unicorn/prefer-array-flat: Skip non-array `flatMap` receivers (#23527) (Yunfei He) - 3e6f90f linter/unicorn/no-zero-fractions: Insert a space after any preceding keyword (#23529) (Yunfei He) - 79a7d69 linter/eslint/no-useless-assignment: Handle exceptional control-flow paths (#23544) (camc314) - e8e2741 linter/unicorn/prefer-math-min-max: Preserve operand source text in the fix (#23533) (Yunfei He) - f592154 linter/react/display-name: Ignore lowercase jsx helpers (#23510) (camc314) - df7612f linter/jsx-a11y/no-noninteractive-element-to-interactive-role: Allow custom roles config (#23507) (camc314) - 924b931 linter/unicorn/prefer-at: Handle checking all indexes correctly (#23504) (camc314) - ca9686b linter/unicorn/prefer-at: Report zero indexes (#23503) (camc314) - e96a4e3 linter/unicorn/explicit-length-check: Ignore optional chains (#23487) (camc314) - a303c23 linter/jsx-a11y: Align `anchor-is-valid` config with upstream (#23446) (camc314) - f27a6d1 linter: False positives with non `*.setTimeout` call in `no-confusing-set-timeout` (#23444) (camc314) ### ⚡ Performance - 8e0dd65 linter: Emit RuleEnum dispatch match once instead of per timing branch (#23499) (Boshen) - d5c7d99 linter/expect-expect: Avoid recompiling matches on every traversal (#23593) (camc314) - f191520 linter/no-useless-spread: Avoid collecting `Vec` before iterating (#23546) (camc314) - 79340d1 linter: Stream React lifecycle ancestors (#23545) (camc314) - 1923169 linter/eslint/max-classes: Gate rule by rule config threshold (#23509) (camc314) - 3f60de3 linter: Use bucketed dispatch for all files (#23452) (camc314) - 3699971 linter/typescript/no-unnecessary-parameter-property-assignment: Avoid temporary vec allocations (#23492) (camc314) - 4ef0ceb linter/eslint/no-useless-switch-case: Avoid temporary vec allocations (#23489) (camc314) - 2e09dd3 linter: Avoid JSX fragment child collections (#23486) (camc314) - f30a64c linter/oxc/branches-sharing-code: Borrow shared branch suggestion text (#23484) (camc314) - 097a317 linter/eslint/no-control-regex: Retain control regex candidates in place (#23482) (camc314) - b3a093d linter: Reuse rule dispatch buckets (#23450) (camc314) - 9f1a985 oxlint: Start Tokio only for LSP (#23447) (camc314) ### 📚 Documentation - 9e219de linter/plugins: Update usage instruction (#23495) (Tony) - b50bf4d linter: Remove manually written options doc for `eslint/arrow-body-style` (#23490) (Mikhail Baev) # Oxfmt ### 💥 BREAKING CHANGES - 36009dd allocator: [**BREAKING**] `GetAllocator::allocator` take `&self` (#23676) (overlookmotel) ### 🐛 Bug Fixes - f21ed2c formatter_json: Normalize CRLF for suppressed text (#23702) (leaysgur) - 7cd1737 formatter: Normalize CRLF for suppressed text (#23701) (leaysgur) - a36e444 formatter: Member chain panic when tail is merged with comment in dev build (#23698) (leaysgur) - 600d306 formatter: Preserve parens with default export and type cast (#23697) (leaysgur) - 61290f2 formatter: Single-member intersection/union type with comment formatting (#21915) (Leonabcd123) - 5a1b0b4 formatter: Parenthesize a type assertion used as the base of `**` (#23633) (Jerry Zhao) - 91827e2 formatter: Use `Ordering::reverse()` with `order: desc` for idempotency (#23543) (leaysgur) - 8fa7394 formatter_json: Handle wrapped error span (#23472) (leaysgur) - 37a34a1 oxfmt/lsp: Avoid newlines line ending changes (#23463) (Sysix) ### ⚡ Performance - 80f1697 formatter: Avoid arena copy for already-lowercase bigint literals (#23534) (Yunfei He) - 1a40b71 formatter: Avoid arena copy for borrowed numeric-literal text (#23512) (Yunfei He) - 12e4451 formatter: Avoid arena copy for borrowed string-literal text (#23465) (Yunfei He) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

…23465) ## What & why Every formatted string literal flows through `CleanedStringLiteralText::fmt`, which copied the text into the formatter arena unconditionally: ```rust text(f.allocator().alloc_str(&self.text)).fmt(f); ``` `self.text` is a `Cow<'a, str>`, and in the common case — the literal already uses the preferred quote style and needs no escape normalization — `normalize_text` returns `Cow::Borrowed`, a slice of the source text that already has the `'a` lifetime `FormatElement::Text` requires. So the `alloc_str` copy is redundant for borrowed text. Pass the borrowed slice straight through and only allocate for the owned (normalized) case: ```rust let text_str: &'a str = match &self.text { Cow::Borrowed(borrowed) => borrowed, Cow::Owned(owned) => f.allocator().alloc_str(owned), }; text(text_str).fmt(f); ``` This removes one arena allocation + memcpy per borrowed string literal and avoids duplicating the literal's bytes into the arena (the source text already holds them). It is never more work than before: the borrowed arm skips the allocation; the owned arm is unchanged (the added `match` just replaces the implicit `Cow` deref the old code already performed). ## Memory reduction (arena allocations) Measured with `cargo allocs` (`TestFiles::complicated`). **Only the arena-allocation count drops** — system allocations, reallocs, and arena reallocs are all unchanged: | file | arena allocs: before → after | **reduction** | | --- | --- | --- | | antd.js | 2,638,108 → 2,589,031 | **−49,077 (−1.86%)** | | pdf.mjs | 442,227 → 440,620 | **−1,607 (−0.36%)** | | checker.ts | 1,082,132 → 1,081,176 | **−956 (−0.09%)** | | App.tsx | 214,178 → 213,475 | **−703 (−0.33%)** | | kitchen-sink.tsx | 572,286 → 571,980 | **−306 (−0.05%)** | | binder.ts | 63,981 → 63,948 | **−33 (−0.05%)** | | RadixUIAdoptionSection.jsx | 1,172 → 1,149 | **−23 (−1.96%)** | <details><summary>Raw <code>allocs_formatter.snap</code> diff (updated in this PR)</summary> ```diff File | File size || Sys allocs | Sys reallocs || Arena allocs | Arena reallocs --------------------------------------------------------------------------------------------------------------------------- -checker.ts | 2.92 MB || 18642 | 565 || 1082132 | 118667 +checker.ts | 2.92 MB || 18642 | 565 || 1081176 | 118667 -App.tsx | 415.34 kB || 7588 | 172 || 214178 | 25343 +App.tsx | 415.34 kB || 7588 | 172 || 213475 | 25343 -RadixUIAdoptionSection.jsx | 2.52 kB || 54 | 28 || 1172 | 157 +RadixUIAdoptionSection.jsx | 2.52 kB || 54 | 28 || 1149 | 157 -pdf.mjs | 567.30 kB || 15308 | 342 || 442227 | 43489 +pdf.mjs | 567.30 kB || 15308 | 342 || 440620 | 43489 -antd.js | 6.69 MB || 83239 | 4652 || 2638108 | 302458 +antd.js | 6.69 MB || 83239 | 4652 || 2589031 | 302458 -binder.ts | 193.08 kB || 824 | 43 || 63981 | 6932 +binder.ts | 193.08 kB || 824 | 43 || 63948 | 6932 -kitchen-sink.tsx | 732.90 kB || 20458 | 3156 || 572286 | 60147 +kitchen-sink.tsx | 732.90 kB || 20458 | 3156 || 571980 | 60147 ``` </details> Instruction count (CodSpeed) is neutral, as expected: arena bump-allocation is cheap on the CPU, so removing the copies reduces memory/allocations without materially changing instructions. This is a memory optimization, not a speed one. ## Behavior-preserving The same bytes reach `text()` in both arms. `cargo test -p oxc_formatter` and the prettier conformance suite pass with byte-identical output (no snapshot churn). --- Prepared with AI assistance (automated performance loop) and validated against local allocation snapshots, benchmarks, and the prettier conformance suite; opened as a draft.

…ls (#23534) ## What `BigIntLiteral` formatting previously **always** copied the literal text into the arena via `alloc_str`, even though the common case — an already-lowercase bigint such as `123n` — needs no change. This borrows the source slice straight through and copies into the arena only when the literal actually contains uppercase hex digits (e.g. `0xFFn`). Mirrors the borrow-passthrough already used for string literals (#23465) and numeric literals (#23512). ## Δ `allocs_formatter.snap` (arena bytes): **kitchen-sink.tsx −39**. No regression on any fixture; allocation *count* unchanged. Output is byte-identical (prettier-conformance snapshots unchanged). Prepared with AI assistance.

# Oxlint ### 💥 BREAKING CHANGES - 36009dd allocator: [**BREAKING**] `GetAllocator::allocator` take `&self` (#23676) (overlookmotel) ### 🚀 Features - ff65285 linter: `no-restricted-globals` add missing upstream options (#23663) (Sysix) - 7b8bd89 linter/typescript: Implement suggestion for `no-unnecessary-type-constraint` rule (#23646) (Mikhail Baev) - 0dc2405 linter: Add schema for `eslint/no-restricted-properties` (#23619) (Sysix) - b638d0e linter: Add schema for `node/callback-return` (#23615) (Sysix) - eb8bedc linter: Add schema for `import/extensions` (#23557) (WaterWhisperer) - 46f3625 linter: Implement node/no-sync rule (#23589) (fujitani sora) - b01739a linter: Add schema for `unicorn/numeric-separators-style` (#23554) (Mikhail Baev) - 68afd2a linter/node: Implement `no-mixed-requires` rule (#23539) (fujitani sora) - 59d8893 linter: `unicorn/numeric-separators-style` support missing options (#23524) (Sysix) - a421215 linter: Add schema for `eslint/prefer-destructuring` (#23410) (WaterWhisperer) - 84438be linter/jsdoc: Added missing options to `require-param-description` (#23416) (kapobajza) - c145b72 linter/jsdoc/require-param-type: Implement fixer (#23513) (camc314) - 51910df linter/jsdoc: Add missing options to `require-param-type` rule (#23418) (kapobajza) - e90925f linter/unicorn: Implement prefer-number-coercion rule (#23497) (Shekhu☺️) - dd1c866 linter/vue: Implement no-async-in-computed-properties rule (#23493) (bab) - b02444e linter: Add schema for `react/jsx-no-script-url` (#23475) (WaterWhisperer) - 53509a8 minifier: Treeshake pure typed arrays and Set/Map array literals (#23469) (Dunqing) - a8dce46 linter/unicorn: Implement `max-nested-calls` rule (#23461) (arieleli01212) ### 🐛 Bug Fixes - b1948a1 linter/radix: Avoid panic on `parseInt` with a spread radix argument (#23623) (Jerry Zhao) - f28ccfd linter/prefer-query-selector: Use a compound selector for multiple classes (#23628) (Jerry Zhao) - 13f2970 linter/prefer-numeric-literals: Avoid panic on `parseInt` with a spread radix argument (#23624) (Jerry Zhao) - 57612b3 linter: Report invalid capitalized-comments ignore patterns (#23608) (camc314) - 800ee2a linter/consistent-vitest-vi: Preserve import aliases when rewriting the import (#23568) (Yunfei He) - f78b5e1 linter/consistent-indexed-object-style: Don't leak a stray comma into the value type (#23566) (Yunfei He) - 6b104e8 linter/radix: Detect a trailing comma only after the argument (#23569) (Yunfei He) - 2de20cb linter/unicorn/prefer-at: Correct two-argument `slice().pop()` index (#23565) (Yunfei He) - de778ec linter: `unicorn/numeric-separators-style` preserve dot for floats without decial part (#23553) (Sysix) - 651027c linter/curly: Remove only the block's own braces (#23580) (Yunfei He) - 687e835 linter/array-type: Parenthesize a conditional-type element (#23579) (Yunfei He) - 9c80dff linter/unicorn/no-unnecessary-await: Don't paste operators into invalid syntax (#23556) (Yunfei He) - 46e1463 linter/no-compare-neg-zero: Delete the `-` of a parenthesized `-0` (#23578) (Yunfei He) - d172a97 linter/unicorn/prefer-math-trunk: Skip fixer for LHS with side effects (#23548) (camc314) - 1c3a9bd linter/unicorn/prefer-negative-index: Don't report `Array#with` (#23518) (Yunfei He) - c17db5d linter/unicorn/prefer-spread: Don't report `.slice()` on non-array receivers (#23520) (Yunfei He) - 9cd0c2f linter/unicorn/prefer-date-now: Keep `BigInt` wrapper when fixing `BigInt(new Date())` (#23523) (Yunfei He) - 16bb890 linter/unicorn/prefer-array-flat: Skip non-array `flatMap` receivers (#23527) (Yunfei He) - 3e6f90f linter/unicorn/no-zero-fractions: Insert a space after any preceding keyword (#23529) (Yunfei He) - 79a7d69 linter/eslint/no-useless-assignment: Handle exceptional control-flow paths (#23544) (camc314) - e8e2741 linter/unicorn/prefer-math-min-max: Preserve operand source text in the fix (#23533) (Yunfei He) - f592154 linter/react/display-name: Ignore lowercase jsx helpers (#23510) (camc314) - df7612f linter/jsx-a11y/no-noninteractive-element-to-interactive-role: Allow custom roles config (#23507) (camc314) - 924b931 linter/unicorn/prefer-at: Handle checking all indexes correctly (#23504) (camc314) - ca9686b linter/unicorn/prefer-at: Report zero indexes (#23503) (camc314) - e96a4e3 linter/unicorn/explicit-length-check: Ignore optional chains (#23487) (camc314) - a303c23 linter/jsx-a11y: Align `anchor-is-valid` config with upstream (#23446) (camc314) - f27a6d1 linter: False positives with non `*.setTimeout` call in `no-confusing-set-timeout` (#23444) (camc314) ### ⚡ Performance - 8e0dd65 linter: Emit RuleEnum dispatch match once instead of per timing branch (#23499) (Boshen) - d5c7d99 linter/expect-expect: Avoid recompiling matches on every traversal (#23593) (camc314) - f191520 linter/no-useless-spread: Avoid collecting `Vec` before iterating (#23546) (camc314) - 79340d1 linter: Stream React lifecycle ancestors (#23545) (camc314) - 1923169 linter/eslint/max-classes: Gate rule by rule config threshold (#23509) (camc314) - 3f60de3 linter: Use bucketed dispatch for all files (#23452) (camc314) - 3699971 linter/typescript/no-unnecessary-parameter-property-assignment: Avoid temporary vec allocations (#23492) (camc314) - 4ef0ceb linter/eslint/no-useless-switch-case: Avoid temporary vec allocations (#23489) (camc314) - 2e09dd3 linter: Avoid JSX fragment child collections (#23486) (camc314) - f30a64c linter/oxc/branches-sharing-code: Borrow shared branch suggestion text (#23484) (camc314) - 097a317 linter/eslint/no-control-regex: Retain control regex candidates in place (#23482) (camc314) - b3a093d linter: Reuse rule dispatch buckets (#23450) (camc314) - 9f1a985 oxlint: Start Tokio only for LSP (#23447) (camc314) ### 📚 Documentation - 9e219de linter/plugins: Update usage instruction (#23495) (Tony) - b50bf4d linter: Remove manually written options doc for `eslint/arrow-body-style` (#23490) (Mikhail Baev) # Oxfmt ### 💥 BREAKING CHANGES - 36009dd allocator: [**BREAKING**] `GetAllocator::allocator` take `&self` (#23676) (overlookmotel) ### 🐛 Bug Fixes - f21ed2c formatter_json: Normalize CRLF for suppressed text (#23702) (leaysgur) - 7cd1737 formatter: Normalize CRLF for suppressed text (#23701) (leaysgur) - a36e444 formatter: Member chain panic when tail is merged with comment in dev build (#23698) (leaysgur) - 600d306 formatter: Preserve parens with default export and type cast (#23697) (leaysgur) - 61290f2 formatter: Single-member intersection/union type with comment formatting (#21915) (Leonabcd123) - 5a1b0b4 formatter: Parenthesize a type assertion used as the base of `**` (#23633) (Jerry Zhao) - 91827e2 formatter: Use `Ordering::reverse()` with `order: desc` for idempotency (#23543) (leaysgur) - 8fa7394 formatter_json: Handle wrapped error span (#23472) (leaysgur) - 37a34a1 oxfmt/lsp: Avoid newlines line ending changes (#23463) (Sysix) ### ⚡ Performance - 80f1697 formatter: Avoid arena copy for already-lowercase bigint literals (#23534) (Yunfei He) - 1a40b71 formatter: Avoid arena copy for borrowed numeric-literal text (#23512) (Yunfei He) - 12e4451 formatter: Avoid arena copy for borrowed string-literal text (#23465) (Yunfei He) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

perf(formatter): avoid arena copy for borrowed string-literal text

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hyf0 force-pushed the perf/formatter-cleaned-string-borrowed-passthrough branch from 90d0984 to 9576364 Compare June 16, 2026 02:31

hyf0 marked this pull request as ready for review June 16, 2026 03:05

hyf0 requested review from Dunqing and leaysgur as code owners June 16, 2026 03:05

leaysgur approved these changes Jun 16, 2026

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leaysgur merged commit 12e4451 into oxc-project:main Jun 16, 2026
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This was referenced Jun 17, 2026

refactor(allocator,formatter): consolidate borrow-passthrough into reusable alloc_cow_str #23528

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perf(formatter): avoid arena copy for already-lowercase bigint literals #23534

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oxc-guard Bot mentioned this pull request Jun 22, 2026

release(apps): oxlint v1.71.0 && oxfmt v0.56.0 #23707

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perf(formatter): avoid arena copy for borrowed string-literal text#23465

perf(formatter): avoid arena copy for borrowed string-literal text#23465
leaysgur merged 1 commit into
oxc-project:mainfrom
hyf0:perf/formatter-cleaned-string-borrowed-passthrough

hyf0 commented Jun 16, 2026 •

edited

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codspeed-hq Bot commented Jun 16, 2026 •

edited

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hyf0 commented Jun 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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What & why

Memory reduction (arena allocations)

Behavior-preserving

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codspeed-hq Bot commented Jun 16, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Merging this PR will not alter performance

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hyf0 commented Jun 16, 2026 •

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codspeed-hq Bot commented Jun 16, 2026 •

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