### 💥 BREAKING CHANGES

- 7a76cd3 estree: [**BREAKING**] Make whether to include TS fields a
runtime option (#23574) (overlookmotel)
- e7b6b68 estree: [**BREAKING**] `ESTree` config use methods not consts
(#23573) (overlookmotel)

### 🚀 Features

- 556cc6d data_structures: Add `CodeBuffer::as_str` method (#23571)
(overlookmotel)
- 38c4b06 parser: Add friendly error for adjacent JSX elements (#23378)
(sapphi-red)
- 53509a8 minifier: Treeshake pure typed arrays and Set/Map array
literals (#23469) (Dunqing)
- 09762d9 minifier: Inline const value for read-only vars (#22593)
(Dunqing)

### 🐛 Bug Fixes

- 20375f9 react_compiler: Keep imports referenced only by a computed key
(#23586) (Boshen)
- 31bfd9b minifier: Keep Object introspection calls on a possible Proxy
(#23483) (Dunqing)
- 837a395 parser: Treat a line comment after ':' as leading, not
trailing (#23515) (Dunqing)
- e409fe0 minifier: Keep `new Map`/`WeakSet`/`WeakMap` with a string
argument (#23470) (Dunqing)
- ae02b4e ci/parser: Use `minimal` for vitest reporter (#23457)
(camc314)

### ⚡ Performance

- cf24329 mangler: Compile slot sort once instead of per CAPACITY
(#23577) (Boshen)
- 4058a6a parser: Reduce code bloat from verify_modifiers
monomorphization (#23576) (Boshen)
- 053b0c1 estree: Remove pointless `mem::take` (#23572) (overlookmotel)
- dfb52b6 transformer: Pre-size statement vecs in TS enum & namespace
lowering (#23516) (Yunfei He)
- 970e09a minifier: Compute template-literal inline checks in a single
pass (#23467) (Yunfei He)
- 3170c0e semantic,mangler,minifier: Fix `Semantic::stats` node count
and reuse stats in mangler builds (#23352) (Boshen)
- d1fa6e0 minifier: Evaluate ternary branches once in
minimize_conditional_expression (#23479) (Yunfei He)
- 3fa8051 transformer: Pre-size JSX props vec to attribute count
(#23466) (Yunfei He)
- 488b382 react_compiler: Borrow binding names in prefilter instead of
allocating (#23471) (Yunfei He)
- bcb3894 minifier: Incremental scoping refresh, delete
LiveUsageCollector (#23197) (Dunqing)

### 📚 Documentation

- f68641e data_structures: Improve docs on safety contract (#23575)
(overlookmotel)

Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

…locating (#23471)

## What & why

The React-compiler prefilter (`has_react_like_functions`) runs on
**every file** in `transform()`
before deciding whether to compile it, and walks the whole program (for
non-React files it never
short-circuits). For **every variable declarator and every
assignment-target identifier** it did:

```rust
current_name: Option<String>,
// ...
Some(ident.name.to_string())   // heap String, used only to call is_react_like_name(&str)
```

`ident.name` is already an arena `Ident<'a>` (`as_str()` returns `&'a
str`), and `current_name` is
only ever read by `is_react_like_name(name: &str)`. So the owned
`String` — a heap alloc + memcpy of
the name bytes, per binding, thrown away immediately — is pure waste.
This borrows it instead:

```rust
struct ReactLikeVisitor<'a> { found: bool, current_name: Option<&'a str> }
// ...
Some(ident.name.as_str())      // zero-cost arena borrow
```

**The positive signal:** one heap `String` allocation (malloc/free +
name-byte memcpy) is removed per
declarator and per assignment-target identifier, across the whole
program, on a path that runs for
every file. On non-React files (e.g. a large `binder.ts`) the prefilter
never short-circuits, so this
is thousands of throwaway allocations eliminated. `&str`/`Ident` is
`Copy` and the struct shrinks
(`Option<&str>` 16B vs `Option<String>` 24B), so it is strictly less
work — never more.

`oxc_react_compiler` is **not** covered by `allocs_*.snap`, so there's
no local snapshot to quantify
this; the `react_compiler` CodSpeed benchmark is the arbiter (removing
system `malloc`/`free` is real
retired instructions, so it should register).

## Behavior-preserving

The borrowed `&'a str` holds the identical bytes the `String` did;
`is_react_like_name` is a pure
read. Prefilter include/exclude decisions are byte-for-byte identical.
The lifetime is sound:
`Ident::as_str() -> &'a str` points into the arena (the program's `'a`),
which outlives the visitor.
`cargo test -p oxc_react_compiler` (17 tests) passes; no snapshot drift.

> Note: `prefilter.rs` is vendored from the upstream React Compiler
(`react_compiler_oxc`), but is
> already substantially oxc-diverged (it adds
`ResourceManagementVisitor`, `memo`/`forwardRef`
> handling, etc.). This is an intentional oxc-side idiom tightening —
flagging it for anyone re-syncing.

---

Prepared with AI assistance.

### 💥 BREAKING CHANGES

- 7a76cd3 estree: [**BREAKING**] Make whether to include TS fields a
runtime option (#23574) (overlookmotel)
- e7b6b68 estree: [**BREAKING**] `ESTree` config use methods not consts
(#23573) (overlookmotel)

### 🚀 Features

- 556cc6d data_structures: Add `CodeBuffer::as_str` method (#23571)
(overlookmotel)
- 38c4b06 parser: Add friendly error for adjacent JSX elements (#23378)
(sapphi-red)
- 53509a8 minifier: Treeshake pure typed arrays and Set/Map array
literals (#23469) (Dunqing)
- 09762d9 minifier: Inline const value for read-only vars (#22593)
(Dunqing)

### 🐛 Bug Fixes

- 20375f9 react_compiler: Keep imports referenced only by a computed key
(#23586) (Boshen)
- 31bfd9b minifier: Keep Object introspection calls on a possible Proxy
(#23483) (Dunqing)
- 837a395 parser: Treat a line comment after ':' as leading, not
trailing (#23515) (Dunqing)
- e409fe0 minifier: Keep `new Map`/`WeakSet`/`WeakMap` with a string
argument (#23470) (Dunqing)
- ae02b4e ci/parser: Use `minimal` for vitest reporter (#23457)
(camc314)

### ⚡ Performance

- cf24329 mangler: Compile slot sort once instead of per CAPACITY
(#23577) (Boshen)
- 4058a6a parser: Reduce code bloat from verify_modifiers
monomorphization (#23576) (Boshen)
- 053b0c1 estree: Remove pointless `mem::take` (#23572) (overlookmotel)
- dfb52b6 transformer: Pre-size statement vecs in TS enum & namespace
lowering (#23516) (Yunfei He)
- 970e09a minifier: Compute template-literal inline checks in a single
pass (#23467) (Yunfei He)
- 3170c0e semantic,mangler,minifier: Fix `Semantic::stats` node count
and reuse stats in mangler builds (#23352) (Boshen)
- d1fa6e0 minifier: Evaluate ternary branches once in
minimize_conditional_expression (#23479) (Yunfei He)
- 3fa8051 transformer: Pre-size JSX props vec to attribute count
(#23466) (Yunfei He)
- 488b382 react_compiler: Borrow binding names in prefilter instead of
allocating (#23471) (Yunfei He)
- bcb3894 minifier: Incremental scoping refresh, delete
LiveUsageCollector (#23197) (Dunqing)

### 📚 Documentation

- f68641e data_structures: Improve docs on safety contract (#23575)
(overlookmotel)

Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>