Fix Fiber DEV mode detection

[gaearon]

I fixed a false positive in #693 but we should have a better strategy than relying on a particular function. I think we should pass a completely separate function in Fiber which we'll check for crushed-ness, and keep it explicit. This will require a small change in React.

[ManasJayanth]

The approach, using a self declared testFunc and checking it name in the runtime, taken in earlier ReactDOM.js seems to be missing in ReactDOMFiber.js. Is this the small change in React you are talking about?

If the same approach is taken in Fiber, we again run the same check in devtools right?

[gaearon]

I think something similar is reasonable. We keep testFunc declared in ReactDOMFiber but pass it together with injectInternals() call. Then in DevTools we can assert on it.

I want to check two things:

1. That name is minified
2. That something inside __DEV__ block in testFunc does not exist at all in toString()'d code

[ManasJayanth]

Ah! Interesting. And use regex to check if __DEV__ block is empty?

Edit: Did you mean __DEV__ block is empty, or no __DEV__ block at all? I thought the build process strips the block altogether. In that case its again a simple string check for just __DEV__

[bvaughn]

React DevTools has been rewritten and recently launched a new version 4 UI. The source code for this rewrite was done in a separate repository and now lives in the main React repo (github.com/facebook/react).

Because version 4 was a total rewrite, and all issues in this repository are related to the old version 3 of the extension, I am closing all issues in this repository. If you can still reproduce this issue, or believe this feature request is still relevant, please open a new issue in the React repo: https://github.com/facebook/react/issues/new?labels=Component:%20Developer%20Tools