Martin Gregorie wrote:
IOW if you wish to make functional changes to GPLed code but not to
distribute them under the GPL for some reason, then the only way to do
that is to write a shim that sits between the GPLed code and the rest of
your original code and implement the functional changes in that shim
without making even a single character change to the GPLed code. The
resulting original code can then be distributed using either of the
preceding two methods without violating the GPL.

No, that won't work. That's a technical tweak which only obfuscates
the legal problem without solving it. The resulting product is still
a "derived work" of the GPL code in question.

That's a simplification, reality is more complicated, but that's the
essence.

Max