Since the OpenBLAS build forces warnings on (at least with CMake), then warnings should be considered errors and should be fixed.
/tmp/OpenBLAS/interface/zsyr.c:122:7: warning: variable ‘trans’ set but not used [-Wunused-but-set-variable]
/tmp/OpenBLAS/kernel/x86_64/sgemv_n_4.c:122:13: warning: ‘sgemv_kernel_4x2’ defined but not used [-Wunused-function]
/tmp/OpenBLAS/kernel/x86_64/sgemv_n_4.c:305:17: warning: unused variable ‘xbuffer’ [-Wunused-variable]
/tmp/OpenBLAS/kernel/x86_64/sgemv_n_4.c:306:17: warning: unused variable ‘ybuffer’ [-Wunused-variable]
/tmp/OpenBLAS/kernel/x86_64/../generic/dot.c:50:13: warning: unused variable ‘n1’ [-Wunused-variable]
Since the OpenBLAS build forces warnings on (at least with CMake), then warnings should be considered errors and should be fixed.