I am using a GPL licensed library which stated clearly that it is OK to link to it in commercial projects without the need to publish your own source code (as an exception to the regular GPL that force you to publish the source along with your product).
Let us call this library with an modified GPL license "Library A". Now, there is another library (let us call it "Library B") that link with the Library A. The Library B itself is licensed under GPL but without that exception which allow you to keep the source closed.
My question is:
Is licensing the Library B without this exception too a legal action? I mean since the author(s) of Library B uses Library A, doesn't this force them to add the exception to their library too?
In other words, can link to Library B in my commercial product with the need to publish my source?