webpack passing string rather than a map to babel-loader

[SunnyTam]

Webpack Version:
2.x

Babel Core Version:
6.x

Babel Loader Version:
6.2.x

Please tell us about your environment:
OSX 10.x

What bug I have found is that I cannot not use devtool: sourcemap. It returns exception below

ERROR in ./src/js/index.js
Module build failed: TypeError: /Users/usr/dir/js/project/src/js/index.js: Cannot create property 'mappings' on string '{"version":3,"sources":["/Users/usr/dir/js/project/src/js/index.js"],"names":["store","render","document","getElementById"],"mappings":";;;;AAAA;;;;AACA;;;;AACA;;AACA;;AACA;;;;AACA;;;;AAEA;;;;;;AAEA;;AAEA,IAAMA,QAAQ,+BAAd;;AAEA,mBAASC,MAAT,CACE;AAAA;AAAA,IAAU,OAAOD,KAAjB;AACE;AAAA;AAAA,MAAQ,oCAAR;AACE,wDAAO,MAAK,GAAZ,EAAgB,yBAAhB;AADF;AADF,CADF,EAOEE,SAASC,cAAT,CAAwB,YAAxB,CAPF,E","sourcesContent":["import React from 'react';\nimport ReactDOM from 'react-dom';\nimport { Provider } from 'react-redux';\nimport { browserHistory, Router, Route } from 'react-router';\nimport injectTapEventPlugin from 'react-tap-event-plugin';\nimport configureStore from './store/configureStore';\n\nimport Main from './components/Main';\n\ninjectTapEventPlugin();\n\nconst store = configureStore();\n\nReactDOM.render(\n  <Provider store={store}>\n    <Router history={browserHistory}>\n      <Route path=\"/\" component={Main} />\n    </Router>\n  </Provider>\n  ,\n  document.getElementById('hotel-chat'),\n);\n"]}'
    at /Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/file/index.js:486:27
    at File.mergeSourceMap (/Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/file/index.js:490:8)
    at File.generate (/Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/file/index.js:729:25)
    at File.transform (/Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/file/index.js:564:17)
    at /Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/pipeline.js:50:19
    at File.wrap (/Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/file/index.js:574:16)
    at Pipeline.transform (/Users/usr/dir/js/project/node_modules/babel-core/lib/transformation/pipeline.js:47:17)
    at transpile (/Users/usr/dir/js/project/node_modules/babel-loader/lib/index.js:46:20)
    at Object.module.exports (/Users/usr/dir/js/project/node_modules/babel-loader/lib/index.js:134:16)
 @ multi (webpack)-dev-server/client?http://localhost:3000 webpack/hot/dev-server ./js/index.js

Finally, I found that webpack calling babel-loader function
module.exports = function (source, inputSourceMap) and passing inputSourceMap as a string rather than map. It makes babel not to response correctly.

So, Do I make any incorrect config so that it pass a string rather than map to babel-loader?
Or should it be fixed on babel-loader?

[Astroxslurg]

I have exactly the same bug!
Webpack 2.2.1, Babel-core 6.23.1, Babel-loader 6.3.2, Ubuntu 16.04.

One workaround I have found is to rename the file from .js to .jsx.
I have no idea why this is working, but it does the job while waiting for a proper bug fix / correct way to do things.

[danez]

I'm not sure what webpack changed, we haven't changed anything related to this.

//cc @sokra @jhnns

[jhnns]

If inputSourceMap is defined, there must be a loader involved before the babel-loader. The output of the previous loader is just passed to the next loader, so I'd assume a non-standard behavior of this previous loader.

[icatalina]

Hi! after looking at webpack's documentation, it turns out a JSON parseable string is a valid sourcemap. I raised a PR in to handle this case #889.