Minify: Constants defined before a while-loop are removed or moved out of scope

[rykdesjardins]

I saw this was fixed and merged in #713, but I can't seem to make it work. Using version 0.3.0 from npm, on Linux.

The smallest code snippet I could come up with is the following.

const array = [];
let loopvar = true;
while (loopvar) { loopvar = false }
array.push(0);

REPL - Try it here

To reproduce, we need a variable defined before a while loop, a while loop, and to refer to the previously defined variable.

Actual Output

// Minified
for(var loopvar=!0;loopvar;)loopvar=!1;array.push(0);

// Manually unminified
for(var loopvar=!0;loopvar;) {
  loopvar=!1;
}
array.push(0);

Expected Output

Something similar to this.

var array = [];
for(var loopvar=!0;loopvar;) {
  loopvar=!1;
}
array.push(0);

Details

For the babelrc, I'm only using two presets.

{
  "presets": ["minify", "es2015"]
}

I believe this is coming from the following sub-package (plugin) : https://github.com/babel/minify/tree/master/packages/babel-plugin-transform-merge-sibling-variables. Might take a look at it and see if I can actually contribute and fix.

The most basic npm script I could come up with is babel dev.js -o build.js. For now, I'm using a simple workaround where I define the array in a higher scope, but it's bad programming. I was thinking of maybe using a reducer instead, but I figured this was worth opening an issue anyways.

For a concrete test, try cloning this repo https://github.com/rykdesjardins/lilium-text, run npm install && npm run build, and open the build/liliumtext.js file. You can find another of a similar issue example if you search for the function called createSelectionContext under LiliumText.

Let me know if you need any additional information!

[vigneshshanmugam]

We might need to backport the PR(#826 ) to 0.3.x versions since 0.4.0 uses scoped packages.

[rykdesjardins]

@vigneshshanmugam Quick comment to let you know I appreciate what you guys are doing. I feel the open source community doesn't thank the brightest minds like you enough for all the innovation.

Sending love from Canada. Thanks for working on this!