The following valid code snippet triggers an ICE since GCC 4.3.0 when compiled with "-W":
========================================= struct A { A(); template<typename T> A(const T&); }; struct B : A { B(const B&) {} }; ========================================= bug.cc: In copy constructor 'B::B(const B&)': bug.cc:9: internal compiler error: tree check: expected function_decl, have template_decl in type_has_user_nondefault_constructor, at cp/class.c:4063 Please submit a full bug report, [etc.] In earlier versions we issued the warning: bug.cc: In copy constructor 'B::B(const B&)': bug.cc:9: warning: base class 'struct A' should be explicitly initialized in the copy constructor -- Summary: [4.3/4.4 regression] ICE with copy constructor in derived class Product: gcc Version: 4.4.0 Status: UNCONFIRMED Keywords: ice-on-valid-code, monitored Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: reichelt at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35734