[Bug c++/71402] -Wunused-variable warnings ignore initialization side effects

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71402

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
For reference, I opened bug 71456 for the problems I noted in comment #2.