React Compiler skips components with default destructured props when using @vitejs/plugin-react

[hazhirmohammadi]

Related plugins

• plugin-react

• plugin-react-swc

• plugin-rsc

Describe the bug

When using React Compiler with @vitejs/plugin-react, components with destructured props that have default values, such as variant = 'primary', may be skipped by the compiler and not optimized as expected.

However, the same component works as expected in a Vite project using @vitejs/plugin-react. This issue was initially observed in a project created with the tsdown React Compiler template.

Reproduction

https://github.com/hazhirmohammadi/tsdown-react-compiler

Steps to reproduce

1. Clone the reproduction repository.
2. Install the dependencies:
   npm install
3. Build the project:
   npm run build
4. Inspect the generated output.
5. Compare the compiled output of Button and Button2.
6. Observe that Button is skipped by React Compiler when using the default destructured prop variant = 'primary', while Button2 without the default value is compiled/optimized.

The issue was initially observed in tsdown. Following the recommendation from the tsdown maintainers in the original issue, I tested the same case with Vite and @vitejs/plugin-react to determine whether the issue could be related to the React plugin.

The issue could not be reproduced in the Vite setup.

System Info

System:
    OS: Linux 6.17 Ubuntu 25.10 25.10 (Questing Quokka)
    CPU: (16) x64 Intel(R) Core(TM) i7-10875H CPU @ 2.30GHz
    Memory: 5.08 GB / 14.90 GB
    Container: Yes
    Shell: 5.2.37 - /bin/bash
  Binaries:
    Node: 24.20.0 - /home/hazhir/.local/share/pnpm/bin/node
    npm: 11.6.2 - /home/hazhir/.nvm/versions/node/v24.20.0/bin/npm
    pnpm: 11.25.0 - /home/hazhir/.local/share/pnpm/bin/pnpm
  Browsers:
    Chrome: 153.0.8010.36
    Firefox: 155.0.1
    Firefox Developer Edition: 155.0.1
  npmPackages:
    @vitejs/plugin-react: ^6.0.3 => 6.1.1 
    vite: ^8.1.4 => 8.3.0

Used Package Manager

npm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[hazhirmohammadi]

After investigation, the root cause is in babel-plugin-react-compiler
itself, not in @vitejs/plugin-react.

The compiler silently bails out on components with default destructured
props when running under @babel/core@8, because Babel 8 removed
AssignmentPattern from the LVal alias.

This is already tracked and being fixed in react/react#36956.

Thank you for your response!