the following code doesn't compile with gcc 5.1 error: internal compiler error: unexpected expression '(const accessor_base){dimension<Pair:: first>{0}}' of kind implicit_conv_expr static constexpr accessor_base s_args_constexpr{dimension<Pair::first>{0} }; //CODE: template <unsigned int Coordinate> struct dimension{ template<typename ... T> constexpr dimension(T...t){} }; struct accessor_base{ template<typename ... T> constexpr accessor_base(T...t){} }; template <typename ArgType, typename Pair> struct accessor_mixed{ private: static constexpr accessor_base s_args_constexpr{dimension<Pair::first>{0} }; };
Same problem in 6.0 trunk
This seems to have always failed with an ICE. Reconfirming for all supported versions, including the top of trunk. $ cat t.c && /build/gcc-trunk-bootstrap/gcc/xgcc -B /build/gcc-trunk-bootstrap/gcc -S -Wall -Wextra -Wpedantic -xc++ t.c template <unsigned int Coordinate> struct dimension{ template<typename ... T> constexpr dimension(T...t){} }; struct accessor_base{ template<typename ... T> constexpr accessor_base(T...t){} }; template <typename ArgType, typename Pair> struct accessor_mixed{ private: static constexpr accessor_base s_args_constexpr{dimension<Pair::first>{0} }; }; t.c:16:79: internal compiler error: unexpected expression ‘(const accessor_base){dimension<Pair:: first>{0}}’ of kind implicit_conv_expr static constexpr accessor_base s_args_constexpr{dimension<Pair::first>{0} }; ^ 0x84e015 cxx_eval_constant_expression /src/gcc/trunk/gcc/cp/constexpr.c:3968 0x8515d3 cxx_eval_outermost_constant_expr /src/gcc/trunk/gcc/cp/constexpr.c:4026 0x6d47b4 store_init_value(tree_node*, tree_node*, vec<tree_node*, va_gc, vl_embed>**, int) /src/gcc/trunk/gcc/cp/typeck2.c:822 0x63be15 check_initializer /src/gcc/trunk/gcc/cp/decl.c:6155 0x65c1c8 cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int) /src/gcc/trunk/gcc/cp/decl.c:6675 0x70bc0e grokfield(cp_declarator const*, cp_decl_specifier_seq*, tree_node*, bool, tree_node*, tree_node*) /src/gcc/trunk/gcc/cp/decl2.c:1036 0x758837 cp_parser_member_declaration /src/gcc/trunk/gcc/cp/parser.c:22559 0x734128 cp_parser_member_specification_opt /src/gcc/trunk/gcc/cp/parser.c:22108 0x734128 cp_parser_class_specifier_1 /src/gcc/trunk/gcc/cp/parser.c:21300 0x734128 cp_parser_class_specifier /src/gcc/trunk/gcc/cp/parser.c:21536 0x734128 cp_parser_type_specifier /src/gcc/trunk/gcc/cp/parser.c:15820 0x748f01 cp_parser_decl_specifier_seq /src/gcc/trunk/gcc/cp/parser.c:12744 0x7573c5 cp_parser_single_declaration /src/gcc/trunk/gcc/cp/parser.c:25703 0x75776c cp_parser_template_declaration_after_parameters /src/gcc/trunk/gcc/cp/parser.c:25398 0x758178 cp_parser_explicit_template_declaration /src/gcc/trunk/gcc/cp/parser.c:25630 0x758178 cp_parser_template_declaration_after_export /src/gcc/trunk/gcc/cp/parser.c:25648 0x75f6a9 cp_parser_declaration /src/gcc/trunk/gcc/cp/parser.c:12080 0x75ded6 cp_parser_declaration_seq_opt /src/gcc/trunk/gcc/cp/parser.c:12010 0x75e1e8 cp_parser_translation_unit /src/gcc/trunk/gcc/cp/parser.c:4323 0x75e1e8 c_parse_file() /src/gcc/trunk/gcc/cp/parser.c:37394 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <http://gcc.gnu.org/bugs.html> for instructions.
This is fixed in 7.1.0, I'm adding a testcase and closing the bug.
In fact it's fixed for 6.4.0 too.
Author: paolo Date: Fri May 12 11:24:56 2017 New Revision: 247964 URL: https://gcc.gnu.org/viewcvs?rev=247964&root=gcc&view=rev Log: 2017-05-12 Paolo Carlini <paolo.carlini@oracle.com> PR c++/67687 * g++.dg/cpp0x/constexpr-ice17.C: New. Added: trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-ice17.C Modified: trunk/gcc/testsuite/ChangeLog
Done.