Issue with array filled in a loop and returned at the end

[gyandeeps]

Choose one: is this a bug report or feature request?

This used to work with 0.0.12 but as i upgraded to latest 0.1.4 it broke. I am sorry but not sure which plugin might be causing this as i have no idea about the internals of babili.

Input Code

const getMinQueryNames = (name) => {
    const coll = [];

    for (let i = 0; i < queries.length; i++) {
        const queryName = queries[i].name;

        coll.push(queryName);
        if (queryName === name) {
            break;
        }
    }

    return coll;
};

Babel Configuration (.babelrc, package.json, cli command)

var webpack = require("webpack");
var path = require("path");

module.exports = {
    entry: "./src/index.js",
    output: { 
        filename: "./dist/bundle.js"
    },
    module: {
        rules: [
            {
                test: /\.(js|jsx)$/,
                include: [
                    path.join(__dirname, "src"),
                ],
                use: [
                    {
                        loader: "babel-loader",
                        options: {
                            presets: [["es2015", {"modules": false}], ["babili"]]
                        }
                    }
                ]
            }
        ]
    },
    plugins: [
        new webpack.optimize.ModuleConcatenationPlugin()
    ],
    stats: {
        // Nice colored output
        colors: true
    }
};

Expected Behavior

Output from 0.0.12 version and also the demo site gives this output as well.
Watch the return at end.

var getMinQueryNames=function(a){for(var d,b=[],c=0;c<queries.length&&(d=queries[c].name,b.push(d),d!==a);c++);return b};

Current Behavior

Watch the return at end. At runtime its and error because coll is undefined.

var getMinQueryNames=function(a){for(var b,c=[],d=0;d<queries.length&&(b=queries[d].name,c.push(b),b!==a);d++);return coll};

Your Environment

software	version(s)
Babel	6.25
node	8.0
npm	5.0.3
Operating System	Windows 7

UPDATE

I narrowed it down to mangle and mergeVars plugin. If you use them individually they work fine but if you use them together then they produce this error..

[vigneshshanmugam]

The other option is to use babili as babili-webpack-plugin which operates on the entire bundle as single run instead of having as a preset along with es2015 preset.

There are couple of scoping issues when running babili along with es2015 https://github.com/babel/babili/issues?q=is%3Aissue+is%3Aopen+label%3A%22with+es2015%22

[piersroberts]

curiously you can sticky plaster fix it like this;

const getMinQueryNames = (name) => {
    const coll = [];
    'bananas';
    for (let i = 0; i < queries.length; i++) {
        const queryName = queries[i].name;
        coll.push(queryName);
        if (queryName === name) {
            break;
        }
    }

    return coll;
};

[Mik13]

I've got the same problem, and work around it by using var, where the var still will be pulled into the for loop initializer, but the name when returning it is correct.

I've tried the above solution aswell, which works too, and the var will be before the for loop, and the string will be in the initializer. Quite funny.