Mine

#include <cstdlib>

union blah
{
        void* pnt;
};

blah f() 
{
        return (blah) NULL;
}

int main()
{
        return 0;
}


test9.cpp: In function ‘blah f()’:
test9.cpp:10: error: no matching function for call to ‘blah::blah(NULL)’
test9.cpp:4: note: candidates are: blah::blah()
test9.cpp:4: note:                 blah::blah(const blah&)