[Bug c++/84463] Supposedly-incompliant "error: '* key0' is not a constant expression"

[sergey.ignatchenko at ithare dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84463

--- Comment #1 from sergey.ignatchenko at ithare dot com ---
oops, forgot to mention command line:
g++  -std=c++1z -lstdc++ -Werror ../chachatest.cpp

where chachatest.cpp is provided in "CODE" section above