optional_test_inplace_fail2
../boost/utility/typed_in_place_factory.hpp:57:12: warning: left operand of comma operator has no effect [-Wunused-value]
optional_test_msvc_bug_workaround
../libs/optional/test/optional_test_msvc_bug_workaround.cpp:34:8: warning: unused variable ???xx??? [-Wunused-variable]
optional_test_ref_fail3
../libs/optional/test/optional_test_ref_fail3.cpp:20:25: warning: unused variable ???opt2??? [-Wunused-variable]