[Bug c++/59269] New: [4.9 Regression] ICE with reference in union

["reichelt at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59269

            Bug ID: 59269
           Summary: [4.9 Regression] ICE with reference in union
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org

The following invalid code snippet (compiled with "-std=c++11") triggers an ICE
on trunk:

===================
union U
{
  int& i = 0;
};

void foo()
{
  U();
}
===================

bug.cc:3:12: error: 'U::i' may not have reference type 'int&' because it is a
member of a union
   int& i = 0;
            ^
bug.cc:3:12: error: invalid initialization of non-const reference of type
'int&' from an rvalue of type 'int'
bug.cc: In function 'void foo()':
bug.cc:8:5: internal compiler error: in build_value_init_noctor, at
cp/init.c:385
   U();
     ^
0x6bccdf build_value_init_noctor(tree_node*, int)
        ../../gcc/gcc/cp/init.c:385
0x6bce4c build_value_init(tree_node*, int)
        ../../gcc/gcc/cp/init.c:364
0x606e6b build_functional_cast(tree_node*, tree_node*, int)
        ../../gcc/gcc/cp/typeck2.c:1858
0x66c0b5 cp_parser_functional_cast
        ../../gcc/gcc/cp/parser.c:23013
0x666930 cp_parser_postfix_expression
        ../../gcc/gcc/cp/parser.c:5821
0x669148 cp_parser_unary_expression
        ../../gcc/gcc/cp/parser.c:7109
0x669ddf cp_parser_binary_expression
        ../../gcc/gcc/cp/parser.c:7813
0x66a2d1 cp_parser_assignment_expression
        ../../gcc/gcc/cp/parser.c:8051
0x66c254 cp_parser_expression
        ../../gcc/gcc/cp/parser.c:8213
0x66ca8e cp_parser_expression
        ../../gcc/gcc/cp/parser.c:8252
0x66ca8e cp_parser_expression_statement
        ../../gcc/gcc/cp/parser.c:9551
0x6625e8 cp_parser_statement
        ../../gcc/gcc/cp/parser.c:9402
0x663399 cp_parser_statement_seq_opt
        ../../gcc/gcc/cp/parser.c:9674
0x66350e cp_parser_compound_statement
        ../../gcc/gcc/cp/parser.c:9628
0x676bdb cp_parser_function_body
        ../../gcc/gcc/cp/parser.c:18542
0x676bdb cp_parser_ctor_initializer_opt_and_function_body
        ../../gcc/gcc/cp/parser.c:18578
0x67aefe cp_parser_function_definition_after_declarator
        ../../gcc/gcc/cp/parser.c:22610
0x67bdbd cp_parser_function_definition_from_specifiers_and_declarator
        ../../gcc/gcc/cp/parser.c:22522
0x67bdbd cp_parser_init_declarator
        ../../gcc/gcc/cp/parser.c:16522
0x67d05f cp_parser_simple_declaration
        ../../gcc/gcc/cp/parser.c:11134
Please submit a full bug report, [etc.]