## Summary
- bump the workspace MSRV from 1.95.0 to 1.96.0 under the N-2 policy after #25945
- retain an MSRV-compatible layout calculation while suppressing the Rust 1.98 Clippy suggestion
This PR contains the following updates:
| Package | Type | Update | Change |
|---|---|---|---|
| [rust](https://rust-lang.org/)
([source](https://redirect.github.com/rust-lang/rust),
[changelog](https://redirect.github.com/rust-lang/rust/blob/main/RELEASES.md))
| toolchain | minor | `1.97.1` → `1.98.0` |
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This PR was generated by [Mend Renovate](https://mend.io/renovate/).
View the [repository job
log](https://developer.mend.io/github/oxc-project/oxc).
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---------
Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Cameron <cameron.clark@hey.com>
I started reviewing `minimize_conditional_expression` and looks like
there is alot of wasted effort there, esp, when we are re-creating
`ConditionalExpression` recursively by calling `minimize_conditional`,
for now i decided to only optimize `!==` and `!`, but folding of
`SequenceExpression` and creation of all new
`Expression::new_conditional_expression` could be removed as we should
just mutate current expression
`substitute_unary_plus` removes a `+` when the enclosing binary operator
will do the `ToNumber` conversion anyway. The existing doc comment
reasons carefully about `ToNumber` vs `ToNumeric`, but not about *when*
each runs.
`+a` converts `a` while evaluating `+a`, before the right operand is
evaluated at all. `a - n` converts it in
`ApplyStringOrNumericBinaryOperator`, after `n` has been evaluated.
Dropping the `+` therefore moves the conversion across `n`, and a right
operand with a side effect can change what the conversion sees:
```js
var xs = [];
console.log((+xs) - (xs.push(1), 0)); // 0, converted while `xs` was still empty
// oxc emitted:
console.log(xs - (xs.push(1), 0)); // 1, converted after `xs` grew
```
This PR requires the right operand to be free of side effects before
dropping a `+` in the left position. It cannot observe the conversion
either: under the "Coercion Methods Are Pure" assumption the conversion
runs no user code, so there is nothing to observe.
The right position (`n - +a`) is left as is: `n` is evaluated first
either way, and its `ToNumeric` is a no-op because the existing guard
already established that `n` is a number, so nothing runs between
evaluating `a` and converting it.
`cargo minsize` moves the typescript.js gzip figure down by 10 bytes;
every minified size is identical.
The reproduction was found by the minifier fuzzer (#25594) at seed
12397.
### Differential testing
Every case below was run through oxc and then executed in Node against
the unminified source, comparing the result, the mutated state, and the
error constructor *and message*.
| shape | cases | value worlds | runs |
| --- | ---: | ---: | ---: |
| operator × 37 hand-written right operands | 814 | 41 | 33,374 |
| right operand reading a closure variable the conversion may write |
374 | 41 | 15,334 |
| argument shape (`+a.v`, `+f()`, `+(seq(), a)`, `+(+a)`, getter) ×
nesting | 3,168 | 41 | 129,888 |
| random expressions, 3 seeds, depth 2-3 | 7,500 | 41 | 307,500 |
The worlds cover `[]`, `{ valueOf: () => 10n }`, `Symbol()`,
`Object.create(null)`, objects with getters, `Proxy`, and the numeric
edge cases.
No difference survives, other than one that predates this pass and is
discussed in the doc comment: for a `BigInt` argument both forms throw a
`TypeError`, but `+a` says "Cannot convert a BigInt value to a number"
while `a - 1` says "Cannot mix BigInt and other types". The error kind
never changes.
---
Written with AI assistance (Claude Code). Reviewed by me, and the
before/after behaviour was checked against Node.js.
---------
Signed-off-by: Kotaro Chikuba <miz404@gmail.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
add `boolean_context` to `minimize_not` so negation folding can happen
in-place when possible, reducing extra AST rebuilds and allocations and
`!0` / `!1` can now collapse directly to `1` / `0` in boolean context
Follow-on after #25585.
Pure style change. I hate the way LLMs put line breaks in weird places like after "the" - it makes comments hard to read. And what's with all the colons and semicolons?
No substantive changes, just reformatting comments and docs to avoid this unreadable formatting.
Generate `RuleEnum::to_configuration` arms only for the 33 rules that override the trait default, returning `None` for all other rules.
Release `oxlint`: 12,491,264 → 12,491,200 bytes (-64 bytes). `__text`: 10,589,512 → 10,585,376 bytes (-4,136 bytes).
AI-assisted; reviewed and validated by the contributor.
Statement transforms still use `take_in` after popping or consuming their parent nodes. Removing those dummies is less mechanical because references from discarded branches and pass mutations must remain accounted for.
Move the owned statement fields directly, centralize the shared return/throw conditional rewrite, and use explicit dropped-subtree or mutation reporting at each ownership boundary. The adjacent-`if` rewrite also uses the closure-based replacement API introduced at the bottom of this stack.
Relative to its parent, the tracked allocation fixtures record 2,039 fewer arena allocations and 31,552 fewer arena bytes. Across the complete stack, the improvement is 25,252 arena allocations and 404,352 arena bytes. Minsize output is unchanged.
Validated with `cargo test -p oxc_minifier`, `just minsize`, `cargo clippy -p oxc_minifier -- -D warnings`, `just fmt`, and `git diff --check`.
AI assistance was used for research, implementation, review, and testing. I reviewed and take responsibility for the changes.
Several peephole transforms call `take_in` after removing or consuming the parent AST node. At that point there is no borrowed slot to preserve, so allocating a dummy replacement is unnecessary.
Move those already-owned child nodes directly in the straightforward expression and declaration cases. This second branch stays intentionally mechanical and leaves the statement/reference-bookkeeping cases to the final PR in the stack.
Relative to its parent, the tracked allocation fixtures record 22,957 fewer arena allocations and 370,544 fewer arena bytes. Minsize output is unchanged.
Validated with `cargo test -p oxc_minifier`, `just minsize`, `cargo clippy -p oxc_minifier -- -D warnings`, `just fmt`, and `git diff --check`.
AI assistance was used for research, implementation, review, and testing. I reviewed and take responsibility for the changes.
`replace_expression` currently makes callers extract the old value before constructing its replacement, leaving an arena-backed dummy node behind.
Add a closure-based replacement path that owns the old expression and records the AST mutation. Its dropped-subtree contract remains explicit: callers report discarded subtrees, while values moved into the replacement stay live. Convert the logical-not unwrapping sites whose discarded wrappers contain no references.
This is the foundation of a three-PR Graphite stack. The tracked allocation fixtures record 256 fewer arena allocations and 2,256 fewer arena bytes. Minsize output is unchanged.
Validated with `cargo test -p oxc_minifier`, `just minsize`, `cargo clippy -p oxc_minifier -- -D warnings`, `just fmt`, and `git diff --check`.
AI assistance was used for research, implementation, review, and testing. I reviewed and take responsibility for the changes.
Refactors `try_minimize_if` to improve clarity:
- restructures the function around `alternate` presence rather than
`consequent` type
- removes a recursive `Self::try_minimize_if` call — the fallthrough
after branch-flip achieves the same result
- this also removes need for code duplication for inlining expressions
to `||` or `&&`
- `if (!a) {} else b();` → `a && b();`
- `if (!a) b();` → `a || b();`
- `if (a) {} else b();` → `a || b();`
- `if (a) b();` → `a && b();`
- we also do not have to always call for `wrap_to_avoid_ambiguous_else`
and we can do that after we update code (eg, after rotation, and never
when we convert it to expression)
----------------------
#### changes in stack:
- https://github.com/oxc-project/oxc/pull/25267
- https://github.com/oxc-project/oxc/pull/25178👈
- `main`
Closes#25339.
## The problem
`no-redeclare` gated the entire rule on the file not being an ES module:
```rust
fn should_run(&self, ctx: &ContextHost) -> bool {
// ES modules run in their own scope, and don't conflict with existing globals
!ctx.source_type().is_module()
}
```
The comment justifies the globals half of the rule, and it is right
about that: an ES module has its own top-level scope, so declaring
`Object` or `self` there shadows nothing, which is why ESLint reports
`builtinGlobals` redeclarations against the global scope rather than
inside a module. But the gate took the rest with it — plain `var a = 3;
var a = 10;`, redeclarations in nested scopes, and the TS type/value
collision check added for #10396 all stopped running too.
**One correction to the issue's framing, from testing it rather than
reading it.** `.ts` is parsed as `ModuleKind::Unambiguous`, which
resolves to `Module` only when ESM syntax is actually present. So a
`.ts` file with no `import`/`export` is a script, and the rule *did* run
there — `var a = 3; var a = 10;` on its own is reported today. What was
dead is every `.ts` file that contains an import or an export, which in
practice is nearly all of them. The effect the issue describes is real;
the boundary is ESM syntax, not the extension.
The rule's own tests hid this either way. Every failing case runs under
`.change_rule_path_extension(".cts")` — CommonJS, never a module — and
the single `.ts` block asserts a *pass*, which it would do whether or
not the rule executed.
## The change
Drop `should_run`, and narrow the exemption to the thing the comment
actually describes:
```rust
// ES modules run in their own scope, so a top-level `Object` or `self` shadows nothing.
// Only the globals half of the rule is skipped for them -- redeclaring a local binding is
// still a redeclaration.
let builtin_globals = if self.builtin_globals && !ctx.source_type().is_module() {
Some(&GLOBALS_BUILTIN)
} else {
None
};
```
`builtin_globals` is already the single switch for that half — it drives
`is_builtin`, which chooses between
`no_redeclare_as_builtin_in_diagnostic` and the plain redeclaration
diagnostic — so `None` in modules disables exactly the globals
reporting, for the builtin table and user-configured `globals` alike,
and leaves both redeclaration loops running.
## Tests
A new `.ts` block under the `es-modules` snapshot suffix. Every case
carries ESM syntax so it resolves as a module — otherwise it would test
the script path by accident, which is the trap above:
- **pass** — `export {}; var Object = 0;` and `export {}; var globalThis
= 0;` (a module shadows nothing, so these must stay quiet), plus a
redeclaration-free case and a TS overload pair.
- **fail** — `export {}; var a = 3; var a = 10;`; `export {}; function
f() { var a; var a; }` (nested scope — nothing to do with global scope
at all, and previously silent); the #10396 `type foo = 1; export
function foo(): void; …` case; and `export {}; var Object = 0; var
Object = 0;`.
That last one is the seam this change creates, so it is worth pinning:
inside a module the first `var Object` is no longer reported as
shadowing a builtin, but the second is still reported as a redeclaration
of the first. Without it, narrowing the gate could quietly have turned
builtin-named symbols into a blind spot.
The existing `.cts` blocks and their snapshot are untouched — `.cts` is
CommonJS, so `is_module()` was already false there.
## Verification
Ran locally with `cargo test -p oxc_linter --lib no_redeclare`: passes,
the existing `eslint_no_redeclare.snap` is unchanged, and the new
`eslint_no_redeclare@es-modules.snap` is included. `cargo clippy -p
oxc_linter --lib` is clean.
> AI disclosure, per the contributing policy: I used an AI assistant
while investigating and writing this. I have read and understand the
change, ran the tests myself, and stand behind it.
---------
Co-authored-by: Cameron <cameron.clark@hey.com>
Oxc can shorten variable names and private class names, but it cannot shorten property names such as `obj._field`. This change adds optional property mangling. It replaces #23772 and gives bundlers a way to use the same property names across several files.
### Feature
- `include` selects names to mangle. `exclude` and `reserved` keep names unchanged.
- The cache can give a property a fixed output name or keep it unchanged.
- The mangler supports member access, object and class keys, destructuring, optional chains, the left side of `in`, and JSX property names.
- `mangle_quoted` also handles strings and template literals used directly as property keys. `/* @__KEY__ */` and `/* #__KEY__ */` can mark one other string or template literal as a property key.
- Short names are assigned in a stable order. More common properties get shorter names. Existing and reserved names are avoided.
- Bundlers can collect names from several programs, create one shared map, and apply it to every program.
- Numeric keys, `__proto__`, `constructor`, `prototype`, TypeScript-only keys, and private names are never changed by this pass.
### Design
Property names are part of JavaScript syntax, not local scope. For this reason, the code lives in `oxc_minifier`. It only reuses the short-name generator from `oxc_mangler`.
For one program, the order is:
```text
collect names → assign names → rewrite once → compress → mangle variables and private names
```
Property names are rewritten before compression because compression can remove information about quotes and comments.
For several programs, a bundler collects names from each program, merges the results, assigns one shared map, and rewrites each program once. Collection can run in parallel. All programs must use the same options.
The shared map keeps property names consistent inside one build. The cache has a different job: it keeps fixed names and reservations across separate minify calls.
### Example
With `include: "^_"` and `mangle_quoted: true`:
```js
obj[`_field`] = 1;
obj._field = 2;
```
becomes:
```js
obj[`e`] = 1;
obj.e = 2;
```
### Limitation
- Property mangling is unsafe when other code still uses the old property name. Public APIs and names shared with external code, host APIs, imported namespace objects, or separate builds must be excluded or reserved.
- Quote handling is per use. Without `mangle_quoted`, `obj._field` may change while `obj["_field"]` does not.
- The mangler cannot find names built at runtime or stored in arbitrary strings. Code that uses `eval`, `Function`, or `with` must reserve any affected names.
- Compression may create a matching property after this pass has finished. For example, `'f' + 'oo_'` may later become `foo_` and will not be mangled.
- TypeScript enum reverse mappings are not supported because the transform creates quoted strings.
- Multi-program support is a caller API. The caller must collect every program that shares mangled properties before assigning names.
The public `oxc-minify` API is stacked in #24741. The downstream multi-chunk integration is shown in rolldown/rolldown#10374.
Supersedes #23772.
AI assistance: OpenAI Codex and Claude were used for research, implementation, review, and testing. The contributor is responsible for reviewing and understanding the changes before submission.
Fixes comment-placement bugs, idempotency and also inconsistency around unions/intersections, type aliases, conditional types, and assignment-likes.
- Fix invariant violations where comments crossed `=`, the value, or `;`
- removed the relocation logic emulating old Prettier 3.8 behavior
- Normalize a union's leading comments to one canonical form behind the synthesized leading `|`, independent of the source shape
- Comments around a formatter-added `(` keep their source side of the `(`
- Hug conditional-type branch comments behind `?`/`:` with the content one level under the operator, matching conditional expressions
- Extend `= // c` position preservation from type aliases to all of JS
Remove the inactive `react/config` rule and its generated metadata. Oxlint uses fixed, valid React Compiler options, so the rule cannot produce actionable diagnostics.
AI-assisted: Codex was used to implement and validate this change.
Splits the experimental `react/react-compiler` rule into 24 category-specific rules matching `eslint-plugin-react-hooks` v7.
- Runs React Compiler once per file and routes structured diagnostics to each enabled rule.
- Removes `react/react-compiler` and `reportAllBailouts`, with rules categorized by user-facing lint intent.
- Adds per-rule documentation and deduplicates shared React lint URLs.
- Preserves standardized compiler diagnostics while reporting each finding under its Oxlint rule name.
Breaking change: configurations using `react/react-compiler` must migrate to the category-specific rules.
Written with Claude Code and Codex.
Rejects initialized `let` and `const` declarations in `for...in` during parsing while preserving Annex B's non-strict `var` form.
Adds misc coverage for valid and invalid initializer forms.
Verified with `just ready` and parser conformance.
Closes#25149.
AI-assisted.
Quoted constructor methods bypassed the AST-based constructor validation. Validate type parameters after resolving the method key, preserving the AST shape.
Validation: `just ready`, parser conformance, and allocation checks.
Closes#25692.
AI-assisted with Codex.
## Summary
- report a bare underscore parameter when no args ignore pattern is configured
- preserve the optimized underscore-prefix behavior for explicit argsIgnorePattern configuration
- update focused rule coverage and generated documentation
Closes#25626
## Summary
- run typescript/no-var-requires on JavaScript files
- match typescript-eslint behavior and prevent false unused-disable diagnostics
Fixes#25623.
## Summary
- flag declaration-level TypeScript type-only named default imports
- preserve inline type specifier behavior to match eslint-plugin-import
- add regression and disable-directive coverage
- regenerate rule dispatch and timing metadata
Closes#25613
NOTE: For now, behavior is the same as Prettier.
- Default is `end`
- This works on intersection(`&`) type, but has no effect on union(`|`) type
For future refs: https://github.com/oxc-project/oxc/issues/16367
## Summary
Fix private-name mangling for `get #x()` / `set #x(value)` accessor pairs.
JavaScript treats an accessor pair as one private name, but the mangler previously assigned a candidate per element before collecting into a name-keyed map. The setter overwrote the getter’s mapping, while still consuming an extra candidate.
### Before
```js
class Outer {
get #x() {}
set #x(value) {}
#longName;
nested() {
return class {
#nestedName;
};
}
}
```
```js
class Outer {
get #t() {}
set #t(e) {}
#n;
nested() {
return class {
#r;
};
}
}
```
### After
```js
class Outer {
get #e() {}
set #e(e) {}
#t;
nested() {
return class {
#n;
};
}
}
```
## Implementation
- Deduplicate private names during map construction with `HashMap::entry`.
- Derive nested-class offsets from already-built lexical parent mappings, preserving collision avoidance.
- Pre-size mappings from the number of private elements.
Quoted JSX attribute values do not use ECMAScript escape sequences. Skip strict-mode legacy escape validation for JSX attributes and cover the behavior in misc conformance.
AI-assisted by Codex.
Slots were assigned to non-manglable symbols as well. This made the slot re-use non-optimal.
This PR fixes that.
I used AI to find out this bug and to generate the code and then reviewed the code.
## Summary
Make Codegen conformance failures visible when the Rust reference panics.
- Preserve `null` for source text with parser diagnostics.
- Return a N-API error for a caught reference panic.
- Let Vitest fail the affected fixture instead of silently skipping it.
Pin the Codegen benchmark fixture to an immutable `benchmark-files` commit. This makes benchmark inputs reproducible and prevents `main` updates from silently changing results.
Stop parsing delimited-list elements after a separator when EOF or an undetermined token follows, preventing malformed tuple syntax from creating reversed spans during error recovery.
Validated with `cargo coverage -- parser --filter oxc-23670 --detail`.
AI assistance was used to prepare this change.
Closes#23670.
Add `oxc-codegen` package - a printer written in TS.
### Features
- Prints JS, JSX, TS, TSX.
- Matches `oxc_codegen` exactly on all Test262, TypeScript, Acorn-JSX fixtures.
- Very fast.
### Deficiencies
- Pretty-printing only (no compact/minified output).
- No support for printing comments.
- Source map support is semi-there, but largely untested, and poor API (design doc has some ideas on how to improve it).
### This PR adds
- The printer code.
- Conformance testing infra.
- Further tests for edge cases.
- README.
- Design doc - how it differs from `oxc_codegen` and why, what produces the perf.
### This PR doesn't add
- Not integrated into CI or release pipeline.
### Notes
This started as a slop port of `oxc_codegen`. I've iterated on that base, cleaned it up a lot, and at least skimmed through all of it. I think it's in fairly decent shape.
The design doc is I think worth a read. It explains the rationale for the choices, in particular the "1 codebase, 4 builds" approach.
I've put it in a new top-level directory called `packages`. It's not an app, so didn't seem to me to fit alongside `apps/oxlint` and `apps/oxfmt`. It's pure JS, so not like e.g. `napi/parser`. And it felt too heavyweight to put into `npm` dir. But maybe there's a better place for it.
Co-authored-by: Cameron <cameron.clark@hey.com>
Fixes#23681.
Preserve initial fatal parser errors during top-level `await` reparsing, preventing malformed recovery AST nodes from reaching Oxlint.
Validated with parser unit/conformance suites and allocation snapshots. `just ready` only fails three unrelated ANSI snapshot checks in the current environment.
AI-assisted.
Fix the transformer conformance runner incorrectly marking a fixture as passed that specified `throws` when Oxc produces no error.
Failed conformance cases now always record a diagnostic. This exposes previously hidden failures in the Babel snapshot, including the nested ambient-module fixtures.
Remove the Prettier related stuff from the conformance, which is purely aimed at JS/TS.
Instead, `oxc_formatter_tests` manage Prettier's test fixtures along with Oxfmt.
Replace the generated `RuleEnum::name` match with an ID-indexed static table. This reduced the macOS arm64 release binary by 16,512 bytes (0.118%).
AI assistance was used to analyze binary size and prepare this change. The author reviewed the generated code and measurements.
Co-authored-by: Cameron Clark <cameron.clark@hey.com>
The automated submodule bump #25261 regenerated `runtime.snap` on a loaded CI runner where two tests hit the global timeout, recording transient `timeout: global` failures (`expressions/arrow-function/name.js`, `function-code/10.4.3-1-13-s.js`) and dropping the pass count from 17306 to 17304. Both tests pass on a normal run, so monitor-oxc's Test262 drift check has failed on every run since ([example](https://github.com/oxc-project/monitor-oxc/actions/runs/31359248351/job/93364683855)).
This restores the snapshot to what `cargo coverage runtime` actually produces. Rather than regenerating locally (which could bake in this machine's own timeouts), the CI-reported diff was applied directly and verified byte-identical to CI's output (`git hash-object` matches the diff's `65e3fa9` blob).
Timeouts can get baked in again whenever an automated regen lands on a slow runner; retrying timed-out tests before recording them would close that hole and is left for a follow-up.
This PR was assisted by Claude.
Dunqing