https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64428
Bug ID: 64428 Summary: aggregate with const member as union member [C++03] Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: minor Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: R.HL at gmx dot net struct A { const int b; }; union U { A a; }; int main() { U a = {1, 1}; } Fails to compile using -std=c++03, although it should. Consider that no special member function apart from the destructor is implicitly defined, and the trivialty of them is preserved.