https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66426
--- Comment #1 from James Almer <jamrial at gmail dot com> ---
FWIW, testcase from Comment 2 of pr66405 unedited:
[jamrial@archVM ~]$ cat pr66405_c2.cpp
template <typename> struct A;
template <bool> struct enable_if;
template <typename T, T> struct B;
template <bool... Bools> using and_c = A<B<bool, Bools || true...>>;
template <typename...> using Constructible = int;
template <typename... Ts> struct common_tuple {
template <
typename... Us,
typename enable_if<and_c<(int)Constructible<Ts, Us>()...>::value>::type>
common_tuple();
void foo();
};
template <> void common_tuple<>::foo(){};
[jamrial@archVM ~]$ g++-4.9 -O2 -std=c++11 -c pr66405_c2.cpp
pr66405_c2.cpp:9:63: internal compiler error: unexpected expression
‘int(Constructible())...’ of kind expr_pack_expansion
typename enable_if<and_c<(int)Constructible<Ts, Us>()...>::value>::type>
^
0x61cbd6 cxx_eval_constant_expression
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:9833
0x61e5b6 cxx_eval_outermost_constant_expr
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:9853
0x585cb0 convert_nontype_argument
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:5698
0x585cb0 convert_template_argument
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6590
0x582252 coerce_template_parameter_pack
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6713
0x582252 coerce_template_parms
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6922
0x586c70 lookup_template_class_1
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:7594
0x586c70 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:7895
0x6149b2 finish_template_type(tree_node*, tree_node*, int)
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:2969
0x5d63fa cp_parser_template_id
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:13464
0x5d6613 cp_parser_class_name
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:19195
0x5cc673 cp_parser_qualifying_entity
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:5538
0x5cc673 cp_parser_nested_name_specifier_opt
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:5263
0x5e0ee2 cp_parser_simple_type_specifier
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:14666
0x5c3ebd cp_parser_type_specifier
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:14412
0x5c65cb cp_parser_type_specifier_seq
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18137
0x5d4ee2 cp_parser_type_id_1
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18010
0x5d4fde cp_parser_template_type_arg
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18059
0x5d51d8 cp_parser_template_argument
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:13840
0x5d51d8 cp_parser_template_argument_list
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:13750
And testcase taken from gcc/testsuite/g++.dg/cpp0x/variadic-alias1.C (added in
svn 224163)
[jamrial@archVM ~]$ cat Varidic-alias1.C
template <typename T, T...> struct B;
template <bool... Bools> using and_c = B<bool, +Bools...>;
template <typename T, typename U> using Constructible = int;
template <typename... Ts> struct common_tuple {
template <typename... Us,
typename = and_c<Constructible<Ts, Us>{}...> >
common_tuple();
void foo();
};
template <> void common_tuple<>::foo(){}
[jamrial@archVM ~]$ g++-4.9 -O2 -std=c++11 -c Varidic-alias1.C
Varidic-alias1.C:6:55: internal compiler error: unexpected expression ‘{}...’
of kind expr_pack_expansion
typename = and_c<Constructible<Ts, Us>{}...> >
^
0x61cbd6 cxx_eval_constant_expression
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:9833
0x61e5b6 cxx_eval_outermost_constant_expr
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:9853
0x585cb0 convert_nontype_argument
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:5698
0x585cb0 convert_template_argument
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6590
0x582252 coerce_template_parameter_pack
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6713
0x582252 coerce_template_parms
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:6922
0x586c70 lookup_template_class_1
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:7594
0x586c70 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
/home/jamrial/gcc-4.9-20150603/gcc/cp/pt.c:7895
0x6149b2 finish_template_type(tree_node*, tree_node*, int)
/home/jamrial/gcc-4.9-20150603/gcc/cp/semantics.c:2969
0x5d63fa cp_parser_template_id
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:13464
0x5d6613 cp_parser_class_name
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:19195
0x5cc673 cp_parser_qualifying_entity
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:5538
0x5cc673 cp_parser_nested_name_specifier_opt
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:5263
0x5e0ee2 cp_parser_simple_type_specifier
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:14666
0x5c3ebd cp_parser_type_specifier
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:14412
0x5c65cb cp_parser_type_specifier_seq
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18137
0x5d4ee2 cp_parser_type_id_1
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18010
0x5db5c2 cp_parser_type_id
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:18050
0x5db5c2 cp_parser_type_parameter
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:13161
0x5daeac cp_parser_template_parameter
/home/jamrial/gcc-4.9-20150603/gcc/cp/parser.c:12994
