https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63587
--- Comment #3 from Markus Trippelsdorf <trippels at gcc dot gnu.org> --- Here's another smaller example: % cat test.ii template <class> struct A { }; template <typename> struct B { template <typename> struct C; }; class D; template <typename> class F; struct G { void operator()(const D &, D); }; class D { public: D (int); }; struct H { H (int); }; template <typename _Key, typename, typename, typename _Compare, typename> class I { typedef _Key key_type; template <typename _Key_compare> struct J { _Key_compare _M_key_compare; }; J<_Compare> _M_impl; public: A<int> _M_get_insert_unique_pos (const key_type &); A<int> _M_get_insert_hint_unique_pos (H &); template <typename... _Args> int _M_emplace_hint_unique (H, _Args &&...); }; template <typename _Key, typename _Tp, typename _Compare = G, typename _Alloc = F<A<_Tp> > > class K { typedef _Key key_type; typedef _Key value_type; typedef typename B<_Alloc>::template C<value_type> _Pair_alloc_type; I<key_type, value_type, int, _Compare, _Pair_alloc_type> _M_t; public: void operator[](key_type) { _M_t._M_emplace_hint_unique (0); } }; template <typename _Key, typename _Val, typename _KeyOfValue, typename _Compare, typename _Alloc> A<int> I<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_get_insert_unique_pos ( const key_type &p1) { _M_impl._M_key_compare (p1, 0); } template <typename _Key, typename _Val, typename _KeyOfValue, typename _Compare, typename _Alloc> A<int> I<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_get_insert_hint_unique_pos ( H &) { _M_get_insert_unique_pos (0); } template <typename _Key, typename _Val, typename _KeyOfValue, typename _Compare, typename _Alloc> template <typename... _Args> int I<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::_M_emplace_hint_unique ( H p1, _Args &&...) { _M_get_insert_hint_unique_pos (p1); } namespace { struct L; } void fn1 () { K<D, L> a; a[0]; K<D, int> b; b[0]; } % g++ -c -O2 -std=c++11 -fno-strict-aliasing test.ii test.ii: In function ‘void fn1()’: test.ii:64:28: internal compiler error: tree check: expected var_decl, have result_decl in add_local_variables, at tree-inline.c:4112