[Playground Bug]: Unexpected token, expected "{"

[gkiely]

What kind of issue is this?

• React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
• babel-plugin-react-compiler (build issue installing or using the Babel plugin)
• eslint-plugin-react-compiler (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)
• Playground issue

Link to repro

https://playground.react.dev/#N4Igzg9grgTgxgUxALhAejQAgPIAcEB2mcEBkANgpgIYEAmmUBJAti4QC4A6BGxpYDpgCiMGAEZMAXkwAKAJTSAfJgA8dAJYA3TGiUBuHnxJkhomACZpcxVJWz123UvmHeWE4JFiAzNcc6ejxGWAAqABYaYJgA7hAwANbRAGYaBAgh-KaYAMLWCsqYwJmYmDAIHLBEAc6ZAL4gdUA

Repro steps

Any component created without curly braces will create an error in the console no compiler output is shown.

See playground link.

How often does this bug happen?

Every time

What version of React are you using?

react@rc

What version of React Compiler are you using?

19.0.0-beta-8a03594-20241020

[aalmanasir]

Big

[aalmanasir]

Bug

[dimaMachina]

After my first contribution to react-compiler, I wanted to fix this too, but it seems already fixed?

I tried to install babel-plugin-react-compiler@19.0.0-beta-37ed2a7-20241206 or 0.0.0-experimental-ba7b8e5-20241213 which is out 2 days ago and on my project arrow function with implicit return are still not optimized, do you know @josephsavona which version include this fix? or maybe there is some option to pass to reactCompilerConfig?

[dimaMachina]

ok, I found why I couldn't see optimized components with implicit returns, setting ReactCompilerConfig.compilationMode: 'all' makes them optimized

update

So I consider this as a still a bug since compilationMode: 'infer' doesn't optimize components with implicit returns

[gkiely]

I'm closing this because the playground error is no longer there, it doesn't optimize the arrow function components but that is a separate issue.