[Bug c++/88388] GCC falsely determines string literal to be unused

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88388

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Bisection suggests this was fixed on trunk by r259051 for PR 85113. The
backport to the gcc-7-branch was r259053.