I would be cautious about icf-all with the gold linker, I only feel confident with icf-all with llvm/lld. But as long as it's tested properly s'all good. As it's a end-user application that nothing links against I doubt there will be a problem in this particular case.

In D11940#200778, @joebonrichie wrote:

As it's a end-user application that nothing links against I doubt there will be a problem in this particular case.

That's the idea. It's a game application in the lowest level of a dependency tree, thus not critical. I took the safer route with Telegram as it's a chat application, in fact.