Implementation of GCC's Nested Functions (vs. C++ Lambdas)

This article somehow omits the 80% of both the complexity and the benefits of the GCC nested functions which makes them pointless. Namely you can cast them to function pointers and pass them e.g. as a comparator to the sort() routine. Substituting the right parent frame parameter at the time the nested function is called down the stack is tricky and requires either an explicit support in the ABI (ia-64) or an executable stack to build a trampoline or a special logic to wrap function pointers with a special but set [1].

Without all this nested functions are as useful as the "rewritten" examples in the article, one can easily do that by hand without any compiler or language support.

This problem doesn't arise with C++ lambdas because you pass them around as special objects, not as bare function pointers.

[1] https://gcc.gnu.org/onlinedocs/gccint/Trampolines.html