react/compiler/packages/babel-plugin-react-compiler
mofeiZ ed1264f077
[compiler] Patch array and argument spread mutability (#32521)
Array and argument spreads may mutate stateful iterables. Spread sites
should have `ConditionallyMutate` effects (e.g. mutate if the ValueKind
is mutable, otherwise read).

See
- [ecma spec (13.2.4.1 Runtime Semantics: ArrayAccumulation.
SpreadElement : ...
AssignmentExpression)](https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-runtime-semantics-arrayaccumulation).
- [ecma spec 13.3.8.1 Runtime Semantics:
ArgumentListEvaluation](https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-runtime-semantics-argumentlistevaluation)

Note that
- Object and JSX Attribute spreads do not evaluate iterables (srcs
[mozilla](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax#description),
[ecma](https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-runtime-semantics-propertydefinitionevaluation))
- An ideal mutability inference system could model known collections
(i.e. Arrays or Sets) as a "mutated collection of non-mutable objects"
(see `todo-granular-iterator-semantics`), but this is not what we do
today. As such, an array / argument spread will always extend the range
of built-in arrays, sets, etc
- Due to HIR limitations, call expressions with argument spreads may
cause unnecessary bailouts and/or scope merging when we know the call
itself has `freeze`, `capture`, or `read` semantics (e.g.
`useHook(...mutableValue)`)
We can deal with this by rewriting these call instructions to (1) create
an intermediate array to consume the iterator and (2) capture and spread
the array at the callsite
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/32521).
* #32596
* #32595
* #32594
* #32593
* #32522
* __->__ #32521
2025-03-13 11:58:02 -04:00
..
scripts [compiler] Migrate compiler packages to tsup (#32550) 2025-03-07 16:41:55 -05:00
src [compiler] Patch array and argument spread mutability (#32521) 2025-03-13 11:58:02 -04:00
jest.config.js
package.json [compiler] Dedupe @babel/types (#32581) 2025-03-12 17:02:10 -04:00
README.md
tsconfig.json feat(eslint-plugin-react-hooks): merge rule from eslint-plugin-react-compiler into react-hooks plugin (#32416) 2025-03-12 21:43:06 -04:00
tsup.config.ts feat(eslint-plugin-react-hooks): merge rule from eslint-plugin-react-compiler into react-hooks plugin (#32416) 2025-03-12 21:43:06 -04:00

babel-plugin-react-compiler

React Compiler is a compiler that optimizes React applications, ensuring that only the minimal parts of components and hooks will re-render when state changes. The compiler also validates that components and hooks follow the Rules of React.

This package contains the React Compiler Babel plugin use in projects that make use of Babel. You can find instructions for using this plugin here: https://react.dev/learn/react-compiler