fix(linter/unicorn/prefer-date-now): keep `BigInt` wrapper when fixing `BigInt(new Date())` by hyf0 · Pull Request #23523 · oxc-project/oxc

hyf0 · 2026-06-16T17:25:01Z

Bug

unicorn/prefer-date-now reports and auto-fixes both Number(new Date()) and BigInt(new Date()) by replacing the whole call with Date.now(). That is correct for Number (both are number), but BigInt(new Date()) is a bigint.

Repro

BigInt(new Date()) is auto-fixed to Date.now() — changing a bigint into a number. Downstream bigint usage then breaks at runtime, e.g. BigInt(new Date()) + 1n (works) becomes Date.now() + 1n → TypeError: Cannot mix BigInt and other types.

Expected

Only the inner new Date() is redundant; fix to BigInt(Date.now()), preserving the bigint. This matches eslint-plugin-unicorn, which reports arguments[0] (the new Date()) for the BigInt case rather than the whole call.

Fix

Split the Number/BigInt branch: Number(new Date()) → Date.now() (unchanged); BigInt(new Date()) → replace only the inner new Date() → BigInt(Date.now()), reporting on the new Date() node. Regression test: the BigInt(...) fix expectations now assert BigInt(Date.now()) (snapshot regenerated — only the BigInt diagnostic changes).

Prepared with AI assistance.

…g `BigInt(new Date())` The `{Number,BigInt}(new Date())` branch replaced the whole call with `Date.now()` for both. That is correct for `Number` (both are `number`), but `BigInt(new Date())` is a `bigint` — rewriting it to `Date.now()` changes the type to `number` and breaks downstream `bigint` use (e.g. `... + 1n`). For `BigInt`, only the inner `new Date()` is redundant: fix to `BigInt(Date.now())` and report on the `new Date()` node, matching eslint-plugin-unicorn (which targets `arguments[0]` for the `BigInt` case).

codspeed-hq · 2026-06-16T17:34:38Z

Merging this PR will not alter performance

✅ 5 untouched benchmarks
⏩ 66 skipped benchmarks¹

_{Comparing hyf0:fix/prefer-date-now-bigint (11ab191) with main (16bb890)}

66 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. ↩

# 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>

…g `BigInt(new Date())` (#23523) ### Bug `unicorn/prefer-date-now` reports and auto-fixes both `Number(new Date())` and `BigInt(new Date())` by replacing the whole call with `Date.now()`. That is correct for `Number` (both are `number`), but `BigInt(new Date())` is a `bigint`. ### Repro `BigInt(new Date())` is auto-fixed to `Date.now()` — changing a `bigint` into a `number`. Downstream `bigint` usage then breaks at runtime, e.g. `BigInt(new Date()) + 1n` (works) becomes `Date.now() + 1n` → `TypeError: Cannot mix BigInt and other types`. ### Expected Only the inner `new Date()` is redundant; fix to `BigInt(Date.now())`, preserving the `bigint`. This matches eslint-plugin-unicorn, which reports `arguments[0]` (the `new Date()`) for the `BigInt` case rather than the whole call. ### Fix Split the `Number`/`BigInt` branch: `Number(new Date())` → `Date.now()` (unchanged); `BigInt(new Date())` → replace only the inner `new Date()` → `BigInt(Date.now())`, reporting on the `new Date()` node. Regression test: the `BigInt(...)` fix expectations now assert `BigInt(Date.now())` (snapshot regenerated — only the BigInt diagnostic changes). Prepared with AI assistance. --------- Co-authored-by: Cameron Clark <cameron.clark@hey.com>

# 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>

Sysix added the A-linter Area - Linter label Jun 16, 2026

hyf0 marked this pull request as ready for review June 17, 2026 01:43

hyf0 requested a review from camc314 as a code owner June 17, 2026 01:43

camc314 requested changes Jun 17, 2026

View reviewed changes

Comment thread crates/oxc_linter/src/snapshots/unicorn_prefer_date_now.snap Outdated

revert span changes

13d7aee

camc314 approved these changes Jun 17, 2026

View reviewed changes

Merge branch 'main' into fix/prefer-date-now-bigint

11ab191

camc314 merged commit 9cd0c2f into oxc-project:main Jun 17, 2026
28 checks passed

camc314 self-assigned this Jun 17, 2026

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

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

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Uh oh!

fix(linter/unicorn/prefer-date-now): keep `BigInt` wrapper when fixing `BigInt(new Date())`#23523

fix(linter/unicorn/prefer-date-now): keep `BigInt` wrapper when fixing `BigInt(new Date())`#23523
camc314 merged 3 commits into
oxc-project:mainfrom
hyf0:fix/prefer-date-now-bigint

hyf0 commented Jun 16, 2026

Uh oh!

codspeed-hq Bot commented Jun 16, 2026 •

edited

Loading

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Uh oh!

Conversation

hyf0 commented Jun 16, 2026

Bug

Repro

Expected

Fix

Uh oh!

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

Uh oh!

Merging this PR will not alter performance

Footnotes

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

codspeed-hq Bot commented Jun 16, 2026 •

edited

Loading