[Bug c++/58504] New: ICE with type trait as default template parameter

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58504

            Bug ID: 58504
           Summary: ICE with type trait as default template parameter
           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 valid code snippet triggers an ICE since GCC 4.6.0:

=============================================================
template<bool = __has_nothrow_assign(void)> struct A {};

A<> a;
=============================================================

bug.cc:3:3: internal compiler error: in tsubst_copy, at cp/pt.c:12809
 A<> a;
   ^
0x5b2723 tsubst_copy
        ../../gcc/gcc/cp/pt.c:12809
0x591061 tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        ../../gcc/gcc/cp/pt.c:14738
0x59a4e2 tsubst_expr
        ../../gcc/gcc/cp/pt.c:13628
0x5a755d tsubst_template_arg
        ../../gcc/gcc/cp/pt.c:9235
0x5a3449 coerce_template_parms
        ../../gcc/gcc/cp/pt.c:6802
0x5abc6a lookup_template_class_1
        ../../gcc/gcc/cp/pt.c:7398
0x5abc6a lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ../../gcc/gcc/cp/pt.c:7695
0x6ad202 finish_template_type(tree_node*, tree_node*, int)
        ../../gcc/gcc/cp/semantics.c:2856
0x6456c0 cp_parser_template_id
        ../../gcc/gcc/cp/parser.c:13218
0x6458d2 cp_parser_class_name
        ../../gcc/gcc/cp/parser.c:18746
0x63b5ef cp_parser_qualifying_entity
        ../../gcc/gcc/cp/parser.c:5448
0x63b5ef cp_parser_nested_name_specifier_opt
        ../../gcc/gcc/cp/parser.c:5173
0x6462b7 cp_parser_constructor_declarator_p
        ../../gcc/gcc/cp/parser.c:22076
0x6462b7 cp_parser_decl_specifier_seq
        ../../gcc/gcc/cp/parser.c:11313
0x64a1a9 cp_parser_simple_declaration
        ../../gcc/gcc/cp/parser.c:10918
0x64c1b0 cp_parser_block_declaration
        ../../gcc/gcc/cp/parser.c:10867
0x6551ce cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:10764
0x653f2d cp_parser_declaration_seq_opt
        ../../gcc/gcc/cp/parser.c:10650
0x655806 cp_parser_translation_unit
        ../../gcc/gcc/cp/parser.c:3939
0x655806 c_parse_file()
        ../../gcc/gcc/cp/parser.c:28893
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