The following invalid code snippet (compiled with "-std=c++1y") triggers an ICE since GCC 4.8.0:

=======================================
template<int> struct A
{
  template<typename T> operator T();
};

void foo()
{
  A<0>().operator auto();
}
=======================================

bug.cc: In function 'void foo()':
bug.cc:8:24: internal compiler error: in push_access_scope, at cp/pt.c:220
   A<0>().operator auto();
                        ^
0x591647 push_access_scope
        ../../gcc/gcc/cp/pt.c:219
0x5e266c fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node* const*, unsigned int, tree_node*, unification_kind_t, int, bool, bool)
        ../../gcc/gcc/cp/pt.c:15679
0x54d05c add_template_candidate_real
        ../../gcc/gcc/cp/call.c:2923
0x548ce9 add_template_candidate
        ../../gcc/gcc/cp/call.c:3020
0x548ce9 add_candidates
        ../../gcc/gcc/cp/call.c:5075
0x550617 build_new_method_call_1
        ../../gcc/gcc/cp/call.c:7698
0x550617 build_new_method_call(tree_node*, tree_node*, vec<tree_node*, va_gc, vl_embed>**, tree_node*, int, tree_node**, int)
        ../../gcc/gcc/cp/call.c:7884
0x652842 cp_parser_postfix_expression
        ../../gcc/gcc/cp/parser.c:6065
0x6548cd cp_parser_unary_expression
        ../../gcc/gcc/cp/parser.c:7100
0x65543f cp_parser_binary_expression
        ../../gcc/gcc/cp/parser.c:7804
0x65590f cp_parser_assignment_expression
        ../../gcc/gcc/cp/parser.c:8042
0x657e63 cp_parser_expression
        ../../gcc/gcc/cp/parser.c:8204
0x65865e cp_parser_expression
        ../../gcc/gcc/cp/parser.c:8243
0x65865e cp_parser_expression_statement
        ../../gcc/gcc/cp/parser.c:9542
0x64df67 cp_parser_statement
        ../../gcc/gcc/cp/parser.c:9393
0x64ec49 cp_parser_statement_seq_opt
        ../../gcc/gcc/cp/parser.c:9665
0x64edbe cp_parser_compound_statement
        ../../gcc/gcc/cp/parser.c:9619
0x66248b cp_parser_function_body
        ../../gcc/gcc/cp/parser.c:18525
0x66248b cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc/gcc/cp/parser.c:18561
0x6662c3 cp_parser_function_definition_after_declarator
        ../../gcc/gcc/cp/parser.c:22593
Please submit a full bug report, [etc.]