Fix tokens produced when `<<` opens a type argument list. e.g.:
```typescript
type Bar = ReturnType<<T>(x: T) => number>;
```
Previously only 1 `<` token was produced between `ReturnType` and `T`. This PR corrects that so 2 `<` tokens are produced.
TS-ESLint get this wrong too - hence why this wasn't noticed before, as our conformance tests compare to TS-ESLint.
PR submitted to fix TS-ESLint: https://github.com/typescript-eslint/typescript-eslint/pull/12821
In meantime, this PR skips the erroneously failing ESTree tokens conformance tests. We can can re-enable those tests once the fix lands in TS-ESLint.
#26263 added the ability to run tests and conformance for both versions of `oxc_lexer` (SIMD and scalar fallback) on any platform.
Run tests and conformance on CI (both SIMD and scalar) on any PR which touches `oxc_lexer` crate or other files which affect conformance runner.
Additionally, run Clippy on the SIMD version (main Lint CI task doesn't lint it, due to the `target_feature = "avx2"` gate on the code).
All of this sets up `oxc_lexer` crate for further development, catching any regressions in CI.
`oxc_lexer` has 2 implementations:
1\. SIMD-based on x86_64 with AVX2.
2\. Scalar/SWAR fallback which works on all platforms.
Both produce the same output.
This PR enables running the lexer conformance on either implementation. Which implementation is tested depends on what build flags are passed to `cargo coverage`.
It turns out that it's possible to test the SIMD implementation on Mac by compiling as x86_64, and running it under Rosetta 2.
This PR also adds `just` recipes to run tests and conformance on either implementation:
- `just test-lexer`
- `just test-lexer-simd`
- `just conformance-lexer`
- `just conformance-lexer-simd`
These commands should work correctly on any of Linux x86, Windows x86, Mac aarch64.
Refactor the conformance tester for lexer.
The diff is large, as I've reordered the code so it now reads top-to-bottom, but it's pure refactor. The actual logic is exactly as it was before - just moved things around, renamed vars, shortened code etc.
This also fixes some Clippy warnings which were present before, but hidden because this code is gated behind `target_feature = "avx2"`. That changes in next PR #26263, at which point CI would have started failing if the warnings weren't fixed here first.
Small fix to `cargo coverage`.
Previously a typo e.g. `cargo coverage prser` would fall through to the catch-all arm and would run all coverage tasks.
Instead, this PR makes it panic with an error `Unknown coverage task: "prser"`. This ensures you are running what you think you are.
When the parser records a fatal error it fast-forwards the lexer to end of file. `re_lex_template_substitution_tail` did not check for that, so an incomplete template substitution would still re-lex the `}` and derive the token's start from a cursor which had already jumped to the end.
With tokens enabled, that fails the debug assertion in `finish_next_inner`, because the token being replaced is no longer the one on top of the collected token stream. Release builds silently overwrite an unrelated token instead. Tokens are only collected for Oxlint's JS plugins, which bail out if any parsing error, which is why this hadn't been noticed before.
Fix by adding the same `fatal_error` guard, added to other re-lex methods in #11023.
This does make a difference to diagnostics output for invalid code matching this pattern. TypeScript snapshot loses an "Unterminated string" diagnostic on 2 fixtures. Those errors came from the bogus re-lex reading past end of file. Both these fixtures already have an "Unexpected token" error. The additional "Unterminated string" errors were incorrect, and this fix has the side effect of removing them.
Updates the minifier documentation to use supported validation commands and fixes broken relative links. Also refreshes the coverage task README so it no longer advertises removed suite selectors.
## Summary
- follow chained labels to their terminal statement when validating labeled `continue`
- reject label chains that terminate in a non-iteration statement
- add a focused negative coverage fixture and update the parser coverage snapshot
## Summary
Fix a parser panic when a string-named export decodes to a literal `\u` sequence.
Lone-surrogate validation now uses the metadata captured by the lexer instead of rescanning decoded string contents. This also prevents false diagnostics for names such as `"\\uD800"`.
## Before:
```
thread 'main' (10990283) panicked at crates/oxc_ast/src/ast_impl/literal.rs:89:42:
end byte index 4 is out of bounds for string of length 0
stack backtrace:
0: __rustc::rust_begin_unwind
1: core::panicking::panic_fmt
2: core::str::slice_error_fail_rt
3: core::str::slice_error_fail
4: <core::ops::range::RangeTo<usize> as core::slice::index::SliceIndex<str>>::index
5: <str as core::ops::index::Index<core::ops::range::RangeTo<usize>>>::index
6: <oxc_ast::ast::literal::StringLiteral>::is_string_well_formed_unicode
7: <oxc_parser::ParserImpl<oxc_parser::config::NoTokensParserConfig>>::parse_module_export_name
```
Function parameters, TypeScript signatures, and function bodies currently share one Oxc semantic scope. A reference in a parameter can therefore bind to a declaration inside the body, even though JavaScript does not make body declarations visible there. Rolldown may then treat a global as local, skip a configured define, or remove live code.
## Example
```js
export function load(value = typeof window !== "undefined") {
var window;
return value;
}
```
The body `var window` is not visible to the default value. Before this change, Oxc resolved `window` in the default value to that body declaration. It should remain a global reference.
The workaround resolves parameter and signature references before visiting the body, while only parameter bindings are present. If a reference is still unresolved, its `lookup_scope_id` advances to the function's parent. Final resolution resumes there, so declarations added while visiting the body are skipped. References created in the body still begin at the function scope and resolve normally.
```text
Before: parameter reference -> completed function scope -> body binding (wrong)
After: parameter reference -> parameter bindings -> parent scopes
body reference -> completed function scope -> parent scopes
```
Parameter decorators already begin in the enclosing class scope, so they are left for normal final resolution. This emulates separate parameter and body scopes until https://github.com/oxc-project/backlog/issues/176 is implemented.
The corrected semantic data also exposes the transformer case covered by #26105.
Verified with semantic and transformer-plugin tests, Clippy, coverage, allocation snapshots, and diff checks. `just ready` completed workspace checks but stopped at a codegen snapshot recorded with Node.js v26.5.0; the local version is v25.8.1.
Closes#20427Closes#22783
Downstream reports:
- https://github.com/rolldown/rolldown/issues/10722
- https://github.com/rolldown/rolldown/issues/10779
AI assistance: OpenAI Codex was used to investigate, implement, and test this change. The contributor is responsible for the submitted change.
Serialize `FormalParameterRest` with its outer span so its range includes parameter decorators. Regenerate the raw-transfer deserializers and remove `sourceMapValidationDecorators.ts` from the ESTree mismatch baseline.
Fixes#26011.
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.
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.
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.
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.
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.
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.
- dispatcher
- string_embedder
- tailwind_sorter
Group these 3 together as `SessionServices`, make them available to `FormatSession`, and pass them around.
## Summary
- parse ordinary class field initializers as `AssignmentExpression`
- reject unparenthesized comma expressions while preserving
parenthesized sequence expressions
- add paired misc conformance fixtures and update the generated
snapshots
## Root cause
Ordinary class field initializers used `parse_expr`, which accepts a
top-level comma and constructs a sequence expression. The ECMAScript
`Initializer` grammar requires an `AssignmentExpression`, so the
unparenthesized comma must remain for the class-element terminator check
to reject.
## Summary
- Align auto-accessor initializer parsing with class-field initializer grammar.
- Add regressions for `in` in a `for` initializer and disallowed inherited `await`/`yield` contexts.
## Root cause
The auto-accessor path only enabled `new.target`. It therefore inherited outer `~In`, `Await`, and `Yield` grammar contexts: `a in b` could not parse in a `for` initializer, while `await` and `yield` could incorrectly parse from enclosing async/generator functions. The fix applies the same `In | NewTarget` addition and `Yield | Await` removal already used for class fields, while retaining AssignmentExpression parsing.
## References
- [ECMAScript `FieldDefinition` grammar](https://tc39.es/ecma262/#prod-FieldDefinition)
- [ECMAScript `Initializer` grammar](https://tc39.es/ecma262/#prod-Initializer)
- [TC39 decorators proposal: class auto-accessors](https://github.com/tc39/proposal-decorators#introduction)
## Summary
Narrow `TSInterfaceHeritage` from a general JavaScript `Expression` to `TSTypeName`.
```rust
pub struct TSInterfaceHeritage<'a> {
pub type_name: TSTypeName<'a>,
pub type_arguments: Option<Box<'a, TSTypeParameterInstantiation<'a>>>,
}
```
## Breaking Change
The Rust AST field changes from:
```rust
expression: Expression<'a>
```
to:
```rust
type_name: TSTypeName<'a>
```
## Why?
The current AST can represent shapes such as:
```ts
interface A extends foo() {}
interface A extends A + B {}
interface A extends new Foo() {}
interface A extends true {}
```
Which is an overly wide type since all of the above variants are invalid.
This PR tightens up the AST, making these invalid variants irrepresentable.
## How to migrate?
This should be a trivial migration:
1. instead of accessing `expression` on `TSInterfaceHeritage`, now access `type_name`
2. change any pattern matching on the `type_name` field to use `TypeName` (this is a smaller subset so should allow deleting code!)
closes https://github.com/oxc-project/backlog/issues/215
Quoted module names are only valid in ambient contexts in TypeScript, but we were accepting them in regular TypeScript files.
This reports TS1035 when a quoted module name appears outside a declaration file or ambient declaration. The conformance snapshots now cover both TypeScript cases, and the old invalid codegen fixture has been replaced with a valid internal module declaration.
## Summary
- report TS1234 for function-local ambient module declarations
- preserve TS1235 for function-local namespace and internal module declarations
- report TS2435 for ambient modules nested in namespaces while allowing module augmentation inside ambient external modules
## Babel Conformance Snapshot Parse Failure
This intentionally introduces one known Babel conformance false positive: `typescript/scope/redeclaration-in-nested-module/input.ts`. The Babel harness supplies `sourceType: "module"`, so Oxc reports TS2435 for its nested ambient module. This affects one unique fixture in both the parser and semantic Babel summaries. This change aligns with TS, and TS expects this error.
Review feedback was that the token kinds should be a real enum rather than a module of u8 constants. The values were listed twice, once as the constants and again in the token_kind_name match, so they now come from one declaration, and tok_kinds and the new Lexer::kinds hand out &[TokenKind] instead of raw bytes.
The discriminants do not move. The pipeline computes kinds arithmetically and blends them in SIMD registers, so it keeps working on u8. Only the aliases in pipeline and the compile-time tables in opmap are re-expressed in terms of the enum, and those fold away at compile time. Reading the bytes back as TokenKind assumes every kind written is a declared discriminant, which a debug assertion checks on every accessor. Output is identical across both corpora and an interleaved A/B against the branch below lands inside the noise floor.
The token tape carried a u32 start per entry and kept whitespace and comments on it as ordinary tokens, so anything reconstructing a token's end had to reach for the next entry and every consumer had to step over trivia. Because whitespace was itself a token, the end of each significant token was already in the array as the start of the following entry, just stored under a different name and then discarded. This publishes one oxc_span::Span per significant token instead, start in the low half and end in the high half, bit-identical to the AST's own Span, with trivia gone from the tape entirely. A span turns out to be a misaligned eight-byte window onto positions the pipeline already had, so build_spans widens and compacts them with a qword permute and a byte shuffle rather than recomputing anything, and compress now fills a fixed staging buffer a chunk of blocks at a time instead of a full-length array, carrying one entry across chunks so the last token of a chunk can still see its end. Eight EOF sentinels spanning (n, n) follow the last token so a consumer can peek a short way past the end without a bounds check, and the hashbang stays on the tape, since its kind sits inside the trivia range and the drop mask excludes it explicitly.
Value lanes, cooked bytes, comment records and diagnostics are byte-identical across both fixture corpora, and the span stream was checked against a scalar reference on every fixture. It costs about 0.22 cyc/byte, roughly 1.0 to 1.5 cycles per significant token, because the tape writes nine bytes per token where it used to write five per entry across about a third more entries than there are real tokens. Worth saying plainly that this one costs throughput rather than winning it. It is a contract change that moves work out of the consumer, and it only pays off once the consumer stops reconstructing ends, skipping trivia and scanning for token boundaries.
## Summary
Migrate seven runtime-only `VisitMut` implementations to `VisitJsMut`.
This avoids monomorphizing pure TypeScript type-space traversal for
these consumers.
## Binary size
On arm64 macOS, `cargo build --release -p oxc_transform_napi` produces a
stripped dylib that changes from 3,365,584 to 3,332,480 bytes: **-33,104
bytes (-0.98%)**. Its Mach-O `__text` section changes from 2,909,108 to
2,876,892 bytes: **-32,216 bytes (-1.11%)**.
AI assistance was used to implement this change. I reviewed and take
responsibility for the result.
<sub>Stack created with <a
href="https://github.com/github/gh-stack">GitHub Stacks CLI</a></sub>
## Summary
- report TypeScript diagnostic TS18041 for `return` statements in class static initialization blocks
- reuse the existing `NewTarget`/`Return` parser-context invariant without adding a new context flag
- update the TypeScript, Babel, and Test262 parser snapshots
## Root cause
Class static blocks disable the parser's `Return` context, so their `return` statements previously fell through to the generic top-level TS1108 diagnostic. Static blocks already enable `NewTarget`, which distinguishes this case when `Return` is absent.
## Summary
- Emit TS8011 when a JavaScript class heritage clause uses TypeScript type arguments.
- Cover the diagnostic with a misc parser failure fixture and snapshot.
## Summary
- add a dedicated diagnostic for invalid `for await` loops
- report “`for await` loops are only allowed…” instead of the generic `await` expression message
- update Babel and TypeScript parser conformance snapshots
## Impact
Users now receive an error that identifies the invalid loop construct directly while retaining the existing guidance to remove `await` or mark the enclosing function `async`.
## Summary
- report invalid `for await` loops inside non-async functions immediately, including when an unambiguous source later resolves to a module
- update the TypeScript parser conformance snapshot with the newly reported diagnostics
## Root cause
The parser deferred every `for await` context error in unambiguous sources as a script-only error. When later `export` syntax resolved the source as a module, it discarded that deferred error even when the loop was nested inside a non-async function, where `await` is never permitted.
Fixes#24804.
Recognize `!` as a type-start token so `?` after `satisfies` remains the conditional-expression operator instead of being consumed as a JSDoc nullable type.
Validated with `just ready`.
AI-assisted.
Closes the migration tracked in #23043.
The new builder API (methods on the AST types themselves) has been in place for a while, all Oxc crates are migrated, and every crate which uses `AstBuilder` already enables `disable_old_builder` in its tests. The module docs said "after a few weeks, we will remove `AstBuilder`'s own methods entirely" — this does that.
## What's removed
- `crates/oxc_ast/src/generated/ast_builder.rs` and `builder/methods.rs` — `AstBuilder`'s own node and primitive constructors.
- `AstBuilderGenerator`, which produced the former.
- The `disable_old_builder` Cargo feature, plus the dev-dependency hacks it required across 33 manifests. Eight crates depended on `oxc_ast` *purely* to turn the feature on; those deps and their `cargo-shear` ignore entries are gone too.
## One thing worth reviewing
`AstBuilderGenerator` owned the `#[builder(default)]` / `#[builder(skip)]` attr registration that `BuilderMethodsGenerator` only *reads* — its doc comment said as much. Deleting it naively would have silently dropped `skip`/`default` handling for the 12 AST types using those attrs, so `attrs()` and `parse_attr()` move to `BuilderMethodsGenerator`.
The evidence this was faithful: after regenerating, `builder_methods.rs` and every other generated file are **byte-identical**. The only generated change in the diff is the deletion.
## Breaking changes
- `AstBuilder`'s own methods are gone. Use the AST type methods: `Statement::new_expression_statement(span, expr, &builder)` instead of `builder.statement_expression(span, expr)`.
- `AstBuilder` is no longer `Copy`/`Clone`, and its `allocator` field is private — use the `allocator` method from `GetAllocator`.
- `AstBuilder` and `NONE` are no longer re-exported from the crate root; import them from `oxc_ast::builder`. (The `disable_old_builder` feature already gated these off, so nothing in-tree used the root path.)
- The `disable_old_builder` feature no longer exists — remove it from any manifest that sets it.
A migration note covering all of the above is in `crates/oxc_ast/src/builder/mod.rs`.
---
Implemented with AI assistance (Claude Code); design, review, and verification driven by the author per the repo AI-usage policy.
## Summary
- allow `eval` and `arguments` as direct bindings in ambient declarations
- continue reporting strict-mode errors for destructured ambient bindings
- add focused coverage for declared functions, classes, object patterns, and array patterns
## Why
The semantic checker previously identified allowed bindings by walking to a `TSDeclareFunction`. That missed other ambient declarations, including declared class constructors and methods, and produced diagnostics for TypeScript cases that require no runtime code generation.
The check now uses the existing ambient-context state and rejects only destructuring binding shapes.
## Summary
Adds context notes to `Cannot assign to '{x0}' in strict mode` diagnostics, explaining whether strict mode comes from an explicit directive, class body, or module.
Fixes `import =` semantic reference resolution so internal module references are resolved as namespace lookups instead of ordinary value reads.
TypeScript treats the RHS of an internal `import =` specially. In the checker, `getTargetOfImportEqualsDeclaration` delegates internal module references to `getSymbolOfPartOfRightHandSideOfImportEquals`, which resolves bare RHS names and intermediate qualified names with `SymbolFlags.Namespace` rather than value meaning:
- `getTargetOfImportEqualsDeclaration`: https://github.com/microsoft/TypeScript/blob/f350b52331494b68c90ab02e2b6d0828d2a22a74/src/compiler/checker.ts#L3708-L3733
- `getSymbolOfPartOfRightHandSideOfImportEquals`: https://github.com/microsoft/TypeScript/blob/f350b52331494b68c90ab02e2b6d0828d2a22a74/src/compiler/checker.ts#L4480-L4499
- `getSymbolOfNameOrPropertyAccessExpression` also routes names on the RHS of import/export assignments through that same helper: https://github.com/microsoft/TypeScript/blob/f350b52331494b68c90ab02e2b6d0828d2a22a74/src/compiler/checker.ts#L50014-L50019
Before this change, Oxc could count plain values as references from `import =`:
```ts
const x = 1;
import foo = x;
```
Before:
```text
x references: 1
```
After:
```text
x references: 0
```
That matches TypeScript’s behavior because `x` is only a value symbol, not a namespace-capable symbol.
The same applies to qualified names:
```ts
const x = { y: 1 };
import foo = x.y;
```
Before:
```text
x references: 1
```
After:
```text
x references: 0
```
But namespace-capable declarations still resolve:
```ts
namespace x {}
import foo = x;
```
After:
```text
x references: 1
```
and:
```ts
namespace x {
export namespace y {}
}
import foo = x.y;
```
After:
```text
x references: 1
```
This updates the semantic snapshots to reflect the corrected reference/declaration matching.
## Summary
Reserved-keyword diagnostics now explain the language context that makes an identifier invalid, rather than only reporting that the keyword is reserved.
## Details
- Add context-aware notes for strict mode, classes, and modules.
- Add a dedicated note for `await` in module code.
- Update parser-conformance snapshots for the expanded diagnostics.
Before:
```text
× The keyword 'package' is reserved
```
After, for strict-mode code:
```text
× The keyword 'package' is reserved
note: This identifier is reserved in strict mode code
```
After, for class code:
```js
class Example {
method() {
const static = 1;
}
}
```
```text
× The keyword 'static' is reserved
note: Classes are always strict mode code
```
After, for module code:
```js
export const await = 1;
```
```text
× The keyword 'await' is reserved
note: The identifier `await` is reserved in module code
#24349 made unused-class removal conservatively keep every class whose heritage resolves to a class, lexical, or `var` binding. That preserves class-evaluation errors which the minifier assumptions explicitly allow optimizations to ignore, and it leaves `(class extends Base {});` residue in Rolldown chunks after tree-shaking ([rolldown#10274](https://github.com/rolldown/rolldown/issues/10274)).
The minifier already documents both `No TDZ Violation` and `No side effects from extending a class`, and `oxc_ecmascript` explicitly ignores invalid-superclass errors so removable derived classes are not broadly deoptimized. Treat resolved identifier heritage like other pure reads while retaining the pre-existing literal-arrow exception, including its paren/sequence unwrap. Effects from evaluating the heritage expression, decorators, and effectful class elements remain observable.
The runtime harness already has minifier-only exclusions for unsupported inputs. Six Test262 fixtures covered by these assumptions are skipped only before the minifier variant, with the reason documented beside the list; codegen and transformer still execute, and `runtime.snap` remains unchanged.
## Example
Input:
```js
export var Base = class {};
export var Keep = class extends Base {};
var REMOVE = class extends Base {};
```
Before:
```js
var Base = class {}, Keep = class extends Base {};
(class extends Base {});
export { Base, Keep };
```
After:
```js
var Base = class {}, Keep = class extends Base {};
export { Base, Keep };
```
Verified with `cargo test -p oxc_minifier`, `cargo coverage runtime`, Clippy with warnings denied for `oxc_minifier` and `oxc_coverage`, `just minsize`, `just allocs`, formatting, and `just ready`. Minsize and `runtime.snap` are unchanged; the allocation snapshot records fewer allocations for `kitchen-sink.tsx`.
Implemented with AI assistance (Claude Code and OpenAI Codex). The contributor remains responsible for reviewing, understanding, and submitting the changes under the repository AI usage policy.
## Summary
Make TS1221 underline the generator declaration consistently from the `*` token.
## Why
The previous diagnostic used the generic function span, but that span has different start points depending on how the function is parsed:
- A class method enters function parsing after its name, so `declare class C { *generator(): any; }` highlighted only `(): any;` (starting at column 15), omitting both the generator marker and its name.
- A function declaration starts its span at the `function` keyword, so `declare namespace M { function *generator(): any; }` highlighted the whole declaration (starting at column 5), including text that is not the invalid generator construct.
For example, the prior output treated these equivalent generator markers differently:
```ts
declare class C {
*generator(): any;
// ^^^^^^^^
}
declare namespace M {
function *generator(): any;
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^
}
```
The parser now carries the `*` token location as `Option<u32>` while parsing a function. TS1221 uses that location through the declaration end, so both cases consistently highlight the relevant generator declaration:
```ts
*generator(): any;
^^^^^^^^^^^^^^^^^^
```
The AST continues to store `generator` as a boolean; the location exists only while parsing diagnostics.
## Summary
- report TS1016 while parsing formal parameter lists
- preserve initialized-parameter and rest-parameter behavior
- remove the equivalent semantic check and diagnostic
- update parser and semantic coverage snapshots
Follows #24596, which has now merged.
## Summary
- report TS1242 for abstract constructors in the parser
- remove the equivalent semantic diagnostic
- update TypeScript parser coverage snapshots
## Why?
This check needs to be moved to the parser, as the data is not retained after we change the Constructor ast type.
## Summary
- Report operator-specific diagnostics when unary and `await` expressions are used as exponentiation left operands.
- Reject unparenthesized TypeScript type assertions in the same position while preserving explicitly parenthesized forms.
- Add regression fixtures and update the affected conformance snapshots.
overlookmotel