Migrate the transform-pipeline `Visit` implementors to `VisitJs` (#24499): `oxc_transformer` (3), `oxc_minifier` (4), `oxc_react_compiler` (1), plus the parser regex example and the coverage driver. Part of #24317; linter half in #24530. Behavior is unchanged.
Together with #24530: `oxlint` −129.4 KiB (−0.94%) stripped, `oxc_transform` napi −16.2 KiB (−0.46%).
## Why each visitor can switch
A visitor is safe on `VisitJs` when its hooks cannot observe anything inside the pruned type grammar — either the hooked node kinds are value-space-only, or the AST it walks cannot contain type nodes at that pipeline stage.
| Visitor | File | Why equivalent |
|---|---|---|
| `PrivateInExpressionDetector` | `crates/oxc_transformer/src/decorator/legacy/mod.rs` | Hooks `visit_private_in_expression` (+`visit_decorators`); `#x in y` is runtime-only and cannot occur in type grammar, even inside decorator expressions carrying casts. |
| `BindingMover` | `crates/oxc_transformer/src/es2017/async_to_generator.rs` | Its formal-parameter overrides visit only pattern + initializer (`BindingPattern` carries no type field — annotations are sibling fields it never touches); runs in the exit phase after TS strip. |
| `UsedInJSXBindingsCollector` | `crates/oxc_transformer/src/jsx/refresh.rs` | Runs on un-stripped TSX, but its hooks (JSX-shaped calls, `visit_jsx_opening_element`, declarations/imports) cannot fire inside type grammar; its hand-written `visit_ts_type_annotation` skip-stub is deleted — `VisitJs` prunes that natively. |
| `Finder` | `crates/oxc_react_compiler/src/react_compiler/entrypoint/program.rs` | Matches functions by `scope_id`; real JS function scopes never live in pure type grammar, and `VisitJs` still walks the places one could hide (enum initializers, namespace bodies, cast inner expressions). |
| `KeepVar` | `crates/oxc_minifier/src/keep_var.rs` | Hooks `visit_statement`/`visit_variable_declaration`; statements and `var` declarations don't exist in type space, and namespace/enum bodies (which can contain them) are still walked by `VisitJs`. |
| `DirectEvalFlagCheck` | `crates/oxc_minifier/src/peephole/mod.rs` | Debug-only; hooks `visit_call_expression` only — call expressions cannot occur in valid type grammar. |
| `LiveDirectEvalCollector` | `crates/oxc_minifier/src/peephole/mod.rs` | Same single call-expression hook; type-space-immune regardless of input. |
| `TestVisitor` | `crates/oxc_minifier/tests/ecmascript/prop_name.rs` | Test helper parsing `SourceType::default()` (plain JS); single non-recursing `visit_object_expression` hook. |
| `RegularExpressionVisitor` | `crates/oxc_parser/examples/regular_expression.rs` | Finds `RegExpLiteral` / `new RegExp(...)`; neither node kind can occur in type grammar. |
| `CheckASTNodes` | `tasks/coverage/src/driver.rs` | Its only active override is `visit_reg_exp_literal` (regex print idempotency); `RegExpLiteral` cannot occur in type space. (The commented-out `visit_span` full-AST check would need `Visit` if ever revived.) |
Left on `Visit`: the minifier's incremental-scoping bookkeeping (`DropDiff`, `OverPruneCheck`, `LiveRefCollector`) — dropping `let x: Foo = …` must unmark the type-space `Foo` reference, which the `peephole::remove_unused_declaration` tests verify (they fail under `VisitJs`; confirmed and reverted during this work). `ChildScopeCollector` also stays: TS type nodes (mapped/conditional/function types) carry real `scope_id`s it must collect.
---
🤖 This PR was written with the assistance of Claude Code (Claude Fable 5).
Previously, whether to serialize AST to ESTree JSON with/without TS fields was a compile-time option - via 2 different configs `CompactTSSerializer` and `CompactJSSerializer` (and their pretty-printing and with-fixes counterparts).
Turn this into a runtime option instead -
This make serialization a little slower (more branches in either mode, and dead code in JS-only mode) but reduces the size of `oxc-parser` binary as only one `ESTreeSerializer` is generated, instead of 2 (JS-only, and with-TS).
## Summary
Introduces `oxc_diagnostics::Diagnostics` — a `Vec<OxcDiagnostic>` newtype that knows the difference between errors and warnings — and makes it the standard diagnostics return value across oxc.
- **New type**: `Diagnostics` with `has_errors()`, `has_warnings()`, `errors()`, `warnings()`, plus `Vec`-like ergonomics (Deref, `IntoIterator`, `Extend`, `From`/`Into<Vec>`) so most call sites are unchanged.
- **Return types**: `ParserReturn`, `SemanticBuilderReturn`, `IsolatedDeclarationsReturn`, the React Compiler `TransformResult`/`LintResult`, and `TransformerReturn` now expose `diagnostics: Diagnostics` instead of `errors: Vec<OxcDiagnostic>` (the React Compiler's separate `errors`/`warnings` are merged into one severity-tagged list).
- **Behaviour**: a React Compiler **error** now stops the transform (no output), while **warnings** flow through and the transform continues. `compile()` aborts codegen only when `diagnostics.has_errors()` — warnings alone no longer abort (previously any diagnostic did).
## Breaking change
Consumers reading `*.errors` on these return values must read `*.diagnostics`. React Compiler consumers that read `.errors`/`.warnings` separately should use `diagnostics.has_errors()` / `diagnostics.errors()` / `diagnostics.warnings()`.
Parser/semantic/isolated-declarations fatality is otherwise unchanged. Builds on the React Compiler transform feature (#23201).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
This PR contains the following updates:
| Package | Update | Change |
|---|---|---|
| [rust](https://redirect.github.com/rust-lang/rust) | minor | `1.94.1` → `1.95.0` |
---
### Release Notes
<details>
<summary>rust-lang/rust (rust)</summary>
### [`v1.95.0`](https://redirect.github.com/rust-lang/rust/compare/1.94.1...1.95.0)
[Compare Source](https://redirect.github.com/rust-lang/rust/compare/1.94.1...1.95.0)
</details>
---
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Part of #10307. Add `range` option to `oxc-parser`, to add `range` property to nodes in ESTree AST.
---------
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: overlookmotel <theoverlookmotel@gmail.com>
closes#10980
Previously final source type was only computed when `lang` is not set.
It is changed to:
* compute source type from `lang`, use filename extension if `lang` is
not set
* reset the computed source type with 'script` or `module` if provided
Our Rust AST, ESTree AST, and TS-ESTree ASTs are increasingly diverging from each other. It's useful to be able to view any of them.
Alter `oxc_parser` example so that:
* `--ast` prints the Rust AST.
* `--estree` prints ESTree AST or TS-ESTree AST, depending on source type.
Speed up UTF-8 to UTF-16 `Span` conversion by processing span offsets in ascending order.
This involves, for each node, processing `span.start`, then visiting all children and processing their `Span`s, and then finally processing `span.end`.
When the AST has come direct from the parser, this means all offsets are processed 100% in ascending order (and the visitor used here has manually-written visitation methods for the few types where that's not always the case otherwise e.g. `export {x}`).
If the AST *has* been modified, code may have moved around, so ascending order won't necessarily be preserved, but still it *mostly* will.
Optimize for this visitation order. Instead of doing a binary search through the whole UTF8-UTF16 translation table on every single span offset, assume the current offset is in same region as the last. Only resort to binary search as a de-opt when that's not the case. Most JS/TS files don't contain many non-ASCII characters, so these cases will be rare.
Pure refactor. Rename:
* `Program::to_json` to `to_estree_ts_json`.
* `Program::to_pretty_json` to `to_pretty_estree_ts_json`.
This is preparatory work for #9285, which adds `*_js_*` variants of these 2 methods, which omit TypeScript fields.
Also rename the serializers, to include `TS` in their names, for the same reason.
Replace `serde` with a custom serializer specialized for writing JSON.
`impl Serialize` -> `impl ESTree`. I've called it `ESTree` in case we
want to add e.g. `impl Babel` later on.
The main motivation is that with control of the serializer, we can make
it stateful, so we can extend it to, for example, omit TS fields based
on a flag. This is pretty much impossible with `serde`'s interface.
But a side-effect of the simpler implementation is that it's also more
performant.
The usage of `ESTree` trait is very similar to `serde::Serialize`. Main
differences:
* `serialize` method is infallible. Does not return a `Result`.
* `state = serializer.serialize_struct();` instead of `map =
serializer.serialize_map();`.
* `state.serialize_field(...)` instead of `map.serialize_entry(...)`.
* Struct keys must be strings, and JSON-safe (not including `"` or other
characters that require escaping in JSON).
This is a breaking change, as it's possible downstream consumers are
using `serde` to serialize our AST to other formats. I'd guess unlikely,
but possible. We can always implement `serde::Serialize` as well as
`ESTree` further down the line if there's a demand.
Replace `#[allow]` with `#[expect]` through the whole codebase.
This also surfaced many places where the `#[allow]` attributes were outdated/pointless and could be removed entirely.
Only places `#[allow]` remains are:
1. In generated code and macros, where lint errors may or may not be triggered depending on the generated code.
2. A few places where clippy malfunctions. These use e.g. `#[allow(unused, clippy::allow_attributes)]`.
This PR makes 2 changes to improve the existing API that are not very useful.
- Remove `(Literal)Parser` and `FlagsParser` and their ASTs
- Add `with_flags(flags_text)` helper to `ParserOptions`
Here are the details.
> Remove `(Literal)Parser` and `FlagsParser` and their ASTs
Previously, the `oxc_regular_expression` crate exposed 3 parsers.
- `(Literal)Parser`: assumes `/pattern/flags` format
- `PatternParser`: assumes `pattern` part only
- `FlagsParser`: assumes `flags` part only
However, it turns out that in actual usecases, only the `PatternParser` is actually sufficient, as the pattern and flags are validated and sliced in advance on the `oxc_parser` side.
The current usecase for `(Literal)Parser` is mostly for internal testing.
There were also some misuses of `(Literal)Parser` that restore `format!("/{pattern}/{flags}")` back and use `(Literal)Parser`.
Therefore, only `PatternParser` is now published, and unnecessary ASTs have been removed.
(This also obsoletes #5592 .)
> Added `with_flags(flags_text)` helper to `ParserOptions`
Strictly speaking, there was a subtle difference between the "flag" strings that users were aware of and the "mode" recognised by the parser.
Therefore, it was a common mistake to forget to enable `unicode_mode` when using the `v` flag.
With this helper, crate users no longer need to distinguish between flags and modes.
We have a strange workaround for `visit_function` where we pass in `ScopeFlags`, to support creating the scope inside `Function`, but setting different flags for `MethodDefinition`s.
Previously `visit_function` took `Option<ScopeFlags>` and then did `flags.unwrap_or(ScopeFlags::empty()) | ScopeFlags::Function` to it. Personally, I found this confusing. When I was looking at `MethodDefinition`, I was wondering "It's a function, why doesn't it set Function flag too?"
This changes makes it more explicit and clear what `ScopeFlags` everything has.
## Why
Due to the usage of `&'alloc mut T` in `oxc_allocator::Box`, and
`bumpalo::collections::Vec` in `oxc_allocator::Vec`, ast types are
currently invariant over their allocator lifetime `'a`. This prevents
`ouroboros` from generating `borrow_*` on ast type fields, leading to
the unfriendly `with_*` api:
https://github.com/oxc-project/oxc/blob/c250b288ef0b9a3ca72ac01ff96e3e240b78a30d/crates/oxc_parser/examples/multi-thread.rs#L82-L84
## How
- For `oxc_allocator::Vec`, switch to `allocator_api2::vec::Vec`, which
has a covariant relationship with the allocator lifetime.
- For `oxc_allocator::Box`, use `std::ptr::NonNull` which is
specifically designed to be covariant. I don't use
`allocator_api2::boxed::Box` because it holds the allocator for
dropping, so the size is bigger.
## Downside
Now that `oxc_allocator::Box` uses the unsafe `NonNull`. It has to be a
private field to be safe. This make it impossible to do `Box(....)`
pattern matching.
* move `visit` and `visit_mut` modules to a super module called `visit`
* add `walk_mut` module containing walk functions
* update `enter_node` and `leave_node` events to not pass a reference in the `VisitMut` trait
* add `AstType`, a non-referencing version of `AstKind` to use with `VisitMut` trait
* update the `VisitMut` trait's usages.
Boshen