#include 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&)