Packager not handling .babelignore'd files due to sourcemap generation logic

Description

I have a need to bundle a pre-optimized external lib with my RN application. Until RN 0.42 I had been using a .babelignore to prevent the packager from trying to optimize this file and choke.

It seems in 0.42 and higher I’m no longer allowed to ignore the file.

This issue has also been reported as https://github.com/facebook/react-native/issues/12071

I’ve chatted with @loganfsmyth from BabelJS and his comments were:

cool, I think this is a regression in react-native, their code in that stacktrace is not handling ignored files: https://github.com/facebook/react-native/blob/master/packager/transformer.js#L110, ast will be undefined if the file was ignored (edited) I believe that code was added recently for their faster sourcemap generation logic

Reproduction Steps and Sample Code

A project running 0.43.0-rc4 which produces a more verbose error than 0.42 does is here:

https://github.com/kevinold/RNBabelIgnoreIssue

Upon running react-native run-ios the following error is produced:

error: bundling: TypeError: Cannot read property 'tokens' of undefined
    at new Generator (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/babel-generator/lib/index.js:51:21)
    at exports.default (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/babel-generator/lib/index.js:19:13)
    at Object.transform (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/react-native/packager/transformer.js:110:20)
    at transformCode (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/react-native/packager/src/JSTransformer/worker/worker.js:91:31)
    at exports.transformAndExtractDependencies (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/react-native/packager/src/JSTransformer/worker/worker.js:148:3)
    at handle (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/worker-farm/lib/child/index.js:41:8)
    at process.<anonymous> (/Users/kold/eval-projects/RNBabelIgnoreIssue/node_modules/worker-farm/lib/child/index.js:47:3)
    at emitTwo (events.js:106:13)
    at process.emit (events.js:194:7)
TransformError: /Users/kold/eval-projects/RNBabelIgnoreIssue/epublican-native-context-opt.js: Cannot read property 'tokens' of undefined
Bundling `index.ios.js`  99.0% (403/405), failed.

Solution

Handle babel ignored (in .babelrc ignore sections or .babelignore) files in the packager: https://github.com/facebook/react-native/blob/master/packager/transformer.js#L110

Additional Information

• React Native version: Broken: 0.42-0.43.0-rc4, works on 0.41
• Platform: iOS (I assume Android too)
• Development Operating System: OS X El Capitan

[kevinold]

As a workaround I am using haul to package my app with my ignored files in .babelrc instead of a .babelignore like so:

{
  "presets": ["react-native"],
  "ignore": [
    "my-ignored-lib.js"
  ]
}

[sujitpk-perennial]

@alexanderkjeldaas @GarimaMathur07 I am also getting JavaScript heap out of memory issue for large file. How you resolved this?