The only reason that GCC needs executable trampolines is for the program to be able to create an ordinary function pointer and have all the captured data come along with it. The proposal is to reuse the syntax of nested functions, but change the semantics so that they are no longer callable via ordinary function pointers, but rather "fat pointers" that reference the captured data alongside the raw function address. This is similar to the method used by C++ and does not need trampolines.