[@babel/types] - spreadOperator from an array seems to have a bug with 7.8.7

Bug Report

Current Behavior A clear and concise description of the behavior. When I try to build (with react-scripts 3.4.0), I got this error : Error: C:\Users\thib3113\app\myFile.js: Expected type "Expression" with option {}, but instead got "SpreadElement". at Array.map (<anonymous>)

Input Code

• REPL or Repo link if applicable:

        let communeFound = CommuneService.cachedResults.get(insee) || null;
        if (!communeFound) {
            // spread operator copy the array
            communeFound = [...(await this.search({ insee }, 1))].pop();
        }

this.search return a promise, the promise return an array.

if I replace by communeFound = (await this.search({ insee }, 1)).slice(0).pop(); it’s work

Expected behavior/code A clear and concise description of what you expected to happen (or code). with 7.8.6 it works .

• Babel version(s): 7.8.7
• Node/npm version: Node 13.8.0/npm 6.14.2
• OS: win 10 1909
• Monorepo: no
• How you are using Babel: react-scripts (loader I think)

Is that normal ? or a regression ?

[nicolo-ribaudo]

The problem is that regenerator doesn’t support array spread. All your targets support array spread (so the transform isn’t included), but Chrome 49 doesn’t support generators.

The change in your targets is probably caused by a caniuse update, used by browserslist to decide what browsers it should target.

By default, create-react-app uses >0.2% ad a query to decide which browsers it should target.

You can add this to your package.json to force it to include a browser that doesn’t support array spread, so that it gets compiled:

"browserslist": [
  ">0.2%",
  "chrome 45"
]

(This is still a bug, I will fix it in regenerator).

[nicolo-ribaudo]

Fixes by https://github.com/facebook/regenerator/pull/385