"Copyright The Closure Library Authors" always shows up as the first comment even in code that is ultimately not Apache 2.0 licensed

[kohlschuetter]

When building code that depends on closure-library (or generally, any code that generates important comments, e.g., via @license annotations), these comments show up first in the generated code, even if the license of the final product is different.

The problem is that dependency ordering (certainly with --compilation_level=ADVANCED) reorders JavaScript files such that even the entry point JavaScript file can only trigger a comment section below the "important comments" of its dependencies.

This can ultimately be a legal problem, as users of the file may regard the file as copyrighted/licensed in a clearly wrong way.

I encountered this when using j2cl, which internally uses closure (also see google/j2cl#80). The header of the output shows

/*

 Copyright The Closure Library Authors.
 SPDX-License-Identifier: Apache-2.0
*/

It would be very helpful if there was a simple way to always prepend the Javascript output file with a customizable comment.

That way, you can have a human-readable message (and possibly a SPDX-License-Identifier) that clearly indicates that not everything in the file is licensed as Apache-2.0.

Even better, there should be a way to forcibly suppress all comments in the output, even if @license statements were declared in some dependencies. The output clearly isn't source code anymore, so it doesn't have to carry the license statements.

[niloc132]

See also #3551.

[h-joo]

For now, we suggest to use a workaround to use the --output_wrapper flag to print the valid license on top of the file.