prog.cpp:5:8: error: redefinition of ‘struct tm’
struct tm
^~
In file included from /usr/include/time.h:39,
from /usr/include/pthread.h:24,
from /usr/include/x86_64-linux-gnu/c++/8/bits/gthr-default.h:35,
from /usr/include/x86_64-linux-gnu/c++/8/bits/gthr.h:148,
from /usr/include/c++/8/ext/atomicity.h:35,
from /usr/include/c++/8/bits/ios_base.h:39,
from /usr/include/c++/8/ios:42,
from /usr/include/c++/8/ostream:38,
from /usr/include/c++/8/iostream:39,
from prog.cpp:1:
/usr/include/x86_64-linux-gnu/bits/types/struct_tm.h:7:8: note: previous definition of ‘struct tm’
struct tm
^~