https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90196
--- Comment #1 from Максим Прохоренко <maxim.prohorenko at gmail dot com> --- Start prog.cc:6:19: warning: unused variable 'std_unused_bitset' [-Wunused-variable] std::bitset<20> std_unused_bitset; ^ prog.cc:9:10: warning: unused variable 'unused_double' [-Wunused-variable] double unused_double = 0; ^ prog.cc:10:7: warning: unused variable 'unused_int' [-Wunused-variable] int unused_int = 0; ^ 3 warnings generated. 0 Finish clang-8.0.0 But vector?