[Bug c++/70452] [5/6 Regression] Regression in C++ parsing performance between 4.9.3 and 5.3.1

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70452

--- Comment #8 from Patrick Palka <ppalka at gcc dot gnu.org> ---
So with the patch instead of making ~200k total copies of the same fn (one for
each recursive call) we only make ~15 total copies (the maximum recursion depth
of the function).