in.js:3: ERROR - Duplicate let / const / class declaration in the same scope is not allowed.

Hi,

I have an error while compile a js file with ES6 code:

java -jar closure-compiler-v20170409.jar --compilation_level ADVANCED_OPTIMIZATIONS --js_output_file=in.js out.js

in.js:3: ERROR - Duplicate let / const / class declaration in the same scope is not allowed.
class Storage {
      ^^^^^^^

1 error(s), 0 warning(s)

There is conflict name Storage with something as I guess. If I rename, for example, to _Storage then compilation ends successfully.

"use strict";

class Storage {

}

[brad4d]

The original example doesn’t have an import or export statement in it, so closure-compiler doesn’t consider that to be a module. If you get the same error in a file that does contain either an import or export, I suggest you file a new bug with that example.

[mprobst]

You can put an empty export {}; into a file to mark it as a module.