[Bug c++/97640] GCC doesn't optimize-out outside-affecting lambdas within y-combinator while clang does.

[hotguest1 at hotmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97640

--- Comment #1 from sandthorn <hotguest1 at hotmail dot com> ---
The y-combinator implementation is from Barry's and Mathemagician's answer on
SO.
https://stackoverflow.com/a/40873657/6370128