react/compiler/packages/babel-plugin-react-compiler
Joseph Savona 57d5a59748
[compiler] enablePreserveMemo treats manual deps as non-nullable (#34503)
The `@enablePreserveExistingMemoizationGuarantees` mode can still fail
to preserve manual memoization due to mismtached dependencies.
Specifically, where the user's dependencies are more precise than the
compiler infers bc the compiler is being conservative about what might
be nullable. In this mode though we're intentionally using information
from the manual memoization and can also rely on the deps as a signal
for what's non-nullable.

The idea of the PR is that we treat manual memo deps just like other
inferred-as-non-nullable objects during PropagateScopeDeps. We're
careful to not treat the full path as non-nullable, only up to the last
property index. So `x.y.z` as a manual dep treats `x` and `x.y` as
non-nullable, allowing us to preserve a conditional dependency on
`x.y.z`.

Optionals within manual dependencies are a bit trickier and aren't
handled yet, but hopefully that's less common and something we can
improve in a follow-up. Not handling them just means that developers may
hit false positives on validating existing memoization if they use
optional chains in manual dependencies.

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[//]: # (BEGIN SAPLING FOOTER)
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with [ReviewStack](https://reviewstack.dev/facebook/react/pull/34503).
* #34689
* __->__ #34503
2025-10-02 09:48:52 -07:00
..
scripts
src [compiler] enablePreserveMemo treats manual deps as non-nullable (#34503) 2025-10-02 09:48:52 -07:00
jest.config.js
package.json
README.md
tsconfig.json [compiler] Don't leak global __DEV__ type (#34551) 2025-09-22 16:51:57 +02:00
tsup.config.ts

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