Using computed goto would (probably) make the code compile, but it wouldn't actually work. That's would be heading directly into undefined behavior territory (aka land of the nasal demons).
To give just one or two examples of why this is doomed: imagine you want to jump "inward". If the inner function takes any arguments, you haven't passed them! And if you jump inward, and the inner function then hits a return statement, do you return to the outer function, or to its caller?
And after you resolve all such semantic issues, you need to actually implement all this, without slowing down code which doesn't use this feature.
And all this complexity doesn't buy you much because you have two other options:
1. just call the function to jump inwards, and simply return to jump out.
2. Don't bother with nested functions, and just inline the code.
So it turns out I'm kind of wrong! My arguments for jumping "inward" still seem pretty valid, but they don't generalize to jumping "outward". And indeed, GCC actually allows this, but you need to use the right syntax:
I also can't seem to get there with a plain goto. I can't jump out either. Probably the computed goto extension will do the job, but that is cheating.