CXX      test/test_test_bitcoin-main_tests.o
In file included from test/main_tests.cpp:5:
In file included from ./chainparams.h:11:
In file included from ./primitives/block.h:9:
In file included from ./primitives/transaction.h:9:
In file included from ./amount.h:9:
In file included from ./serialize.h:23:
./prevector.h:419:13: warning: template argument uses unnamed type [-Wunnamed-type-template-args]
            std::swap(_union, other._union);
            ^~~
./script/script.h:618:23: note: in instantiation of member function 'prevector<28, unsigned char, unsigned int, int>::swap' requested here
        CScriptBase().swap(*this);
                      ^
./prevector.h:143:5: note: unnamed type used in template argument was declared here
    union {
    ^
1 warning generated.