http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59482
Bug ID: 59482 Summary: A friend class cannot inherit a private class Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: ville.voutilainen at gmail dot com Test: struct aa { friend struct cc; private: struct bb {}; }; struct cc : aa::bb {}; Output: ville.cpp:1:47: error: ‘struct aa::bb’ is private struct aa { friend struct cc; private: struct bb {}; }; struct cc : aa::bb {}; ^ ville.cpp:1:73: error: within this context struct aa { friend struct cc; private: struct bb {}; }; struct cc : aa::bb {}; ^ Clang 3.4 accepts the code.