Please check this out. Martin pgcc-2.90.29 980515 (egcs-1.0.3 release) err.cc: In function `int main()': err.cc:17: Internal compiler error. err.cc:17: Please submit a full bug report to `egcs-bugs@cygnus.com'. class a; class b { public: operator a(); }; class a { public: a(b); }; b foo(void); main() { a y = foo(); }