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Joe Savona a48d047a6f Update on "[compiler] Null out source locations where not explicitly preserved"

Inspired by #32950. Specifically from https://github.com/facebook/react/issues/32950#issuecomment-2837887871, it sounds like Babel by default emits source map information for all nodes, even when they don't have a `loc` property set. Code coverage tools then pick up the synthesized source location information for this, leading to the issue described.

It wasn't super clear how to omit nodes from the source map. A few google searches didn't turn up any documented way to do so: the user can do so via a function supplied to babel, but plugins can't. Entire files can be opted out, but not nodes. I asked an LLM which answered that explicitly setting `node.loc = null` omits the node from source maps, but that didn't work. 

What did work was explicitly setting the `loc` property to an object that follows the shape of a source location, but with all properties nulled out. With that, we get the desired result:

<img width="553" alt="Screenshot 2025-04-30 at 10 50 30 AM" src="https://github.com/user-attachments/assets/cf55fd32-8375-4cfa-8202-49b45ef02931" />

I'm going to feature-flag this since setting some of these properties in this way might break in other versions of Babel or have other issues.

[ghstack-poisoned]

2025-05-01 12:44:14 +09:00

scripts

[compiler][be] Move e2e tests to BabelPlugin transformer (#32706 )

2025-03-21 20:05:22 -04:00

src

Update on "[compiler] Null out source locations where not explicitly preserved"

2025-05-01 12:44:14 +09:00

jest.config.js

Compiler: unfork prettier config (#30205 )

2024-07-18 17:00:24 -04:00

package.json

[compiler][be] Playground now uses tsup bundled plugin (#32759 )

2025-03-26 14:31:20 -04:00

README.md

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tsconfig.json

[compiler][be] Test runner (snap) now uses tsup bundled plugin (#32758 )

2025-03-26 14:27:42 -04:00

tsup.config.ts

[compiler] Add missing copyrights (#33004 )

2025-04-23 22:04:44 -04:00

README.md

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