Incorrect DCE of assignment to destructered parameter field with ES_2015 or higher

Code sample:

function installBaa({ obj }) {
    obj.baa = 'foo';
}

const obj = {};
installBaa({ obj });
console.log(obj.baa);

Command:

java -jar compiler.jar --js test.js -O ADVANCED --language_out ECMASCRIPT_2015

Version: v20191027

Expected output: (as output by --language_out ECMASCRIPT5)

console.log({a:"foo"}.a);

Actual output:

'use strict';console.log({}.a);

It looks like CC is losing the assignment when the target language is ECMASCRIPT_2015 or higher.

The following non-destructered parameter works as expected:

function installRoutes(x) {
    x.obj.baa = 'foo';
}

[WearyMonkey]

@lauraharker

Any update on this issue?

It forces us to introduce Babel into our pipeline to transpile spread operators before passing Closure Compiler.

[lauraharker]

Sorry about that, I’ll reopen this issue.

link to your original repro