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Issue with `export class Bug { ... }; export default Bug;` in Babel 7

See original GitHub issue

I am seeing this issue with react-native@0.56.0 and metro@0.38.3 (and also metro@0.38.1).

Here’s the code that causes the issue:

export class Bug {

  constructor(props) {
    this.test(props);
  }

  test = (props) => {
    // Error-causing line
    const test = props.test;
  }

}

export default Bug;

The error is:

error: bundling failed: TypeError: Property body[1] of BlockStatement expected node to be of a type ["Statement"] but instead got "ClassExpression"
    at validate (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/definitions/utils.js:130:13)
    at validator (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/definitions/utils.js:97:7)
    at Object.validate (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/definitions/utils.js:177:7)
    at validate (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/validators/validate.js:17:9)
    at builder (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/builders/builder.js:46:27)
    at Object.BlockStatement (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/types/lib/builders/generated/index.js:245:31)
    at NodePath.replaceExpressionWithStatements (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/traverse/lib/path/replacement.js:212:57)
    at NodePath.insertBefore (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/traverse/lib/path/modification.js:47:17)
    at NodePath.unshiftContainer (/Users/ashoat/Dropbox/src/rn56babelbug/node_modules/@babel/traverse/lib/path/modification.js:204:15)

I’ve created a repo with this minimal repro here. I attempted to repro the issue without Metro, by setting up a Babel project with the same code and babel-preset-react-native here, but was unable to repro. My conclusion is that the issue has something to do with how Metro consumes Babel.

Issue Analytics

State:
Created 5 years ago
Comments:8 (4 by maintainers)

Top GitHub Comments

1reaction

kelsetcommented, Aug 28, 2018

I think this may be fixed via Babel 7.0 and Metro 0.44.x (once this is merged https://github.com/facebook/metro/pull/233)

0reactions

rafecacommented, Sep 6, 2018

Yes, we can close this one already! 😄

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