[Bug libstdc++/92267] [9 Regression] crash with a cppunit test case (built by GCC 9) and cpptest (built with GCC 8)

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92267

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Preprocessing with GCC 8 and then compiling with GCC 9 doesn't crash, so it's
due to a change in libstdc++ headers.