Google Closure Advanced build fails when disabling dev mode

[vikeri]

Do you want to request a feature or report a bug?
Regression bug

What is the current behavior?
My minified app will not run if I set dev to false (RN 0.57) and enable Google Closure's advanced compilation (uglifying+dead code elimination). Wit Google Closure optimizations simple it works. In previous versions (0.56) it worked with advanced and dev set to false.
The error it throws is Can't find variable: a

If the current behavior is a bug, please provide the steps to reproduce and a minimal repository on GitHub that we can yarn install and yarn test.
I'm not asking for a fix, just wondering what dev mode does and if something has changed with it since the last release of RN (0.56)?

What is the expected behavior?
That the code should run without errors.

Please provide your exact Metro configuration and mention your Metro, node, yarn/npm version and operating system.

[vikeri]

More info: I found that it's the addition of this line that causes the issue:

metro/packages/metro/src/JSTransformer/worker.js

Lines 241 to 244 in 60bad94

	if (!options.dev) {
	plugins.push([constantFoldingPlugin, opts]);
	plugins.push([inlinePlugin, opts]);
	}

Introduced here:
f8cfe20#diff-d72b0c05df0019a0d596696cfea58ae4R229

What does that if-statement do?

[chpill]

This is a duplicate of #291

As for why the if statement is there, my guess is that these optimizations make producing the JS bundle a lot longer, which is not pleasant during development.

[vikeri]

Closing this since it's a duplicate