[Bug c++/80244] New: [6/7 Regression] ICE with attribute in template alias

[reichelt at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80244

            Bug ID: 80244
           Summary: [6/7 Regression] ICE with attribute in template alias
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: reichelt at gcc dot gnu.org
  Target Milestone: ---

The following code snippet triggers an ICE since GCC 6.1.0:

======================================================================
template<typename> struct A {};

template<typename T> using B = A<__underlying_type(T) [[gnu::aligned(4)]]>;
======================================================================

bug.cc:3:67: internal compiler error: in layout_type, at stor-layout.c:2386
 template<typename T> using B = A<__underlying_type(T) [[gnu::aligned(4)]]>;
                                                                   ^
0xd5a9bf layout_type(tree_node*)
        ../../gcc/gcc/stor-layout.c:2386
0x1027845 type_hash_canon(unsigned int, tree_node*)
        ../../gcc/gcc/tree.c:7131
0x1027d2d build_type_attribute_qual_variant(tree_node*, tree_node*, int)
        ../../gcc/gcc/tree.c:4875
0x7ce47d cp_build_type_attribute_variant(tree_node*, tree_node*)
        ../../gcc/gcc/cp/tree.c:4156
0x7dd9f2 strip_typedefs(tree_node*, bool*)
        ../../gcc/gcc/cp/tree.c:1580
0x6478ac canonicalize_type_argument
        ../../gcc/gcc/cp/pt.c:7331
0x68db53 coerce_template_parms
        ../../gcc/gcc/cp/pt.c:8128
0x6947ea lookup_template_class_1
        ../../gcc/gcc/cp/pt.c:8664
0x6947ea lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ../../gcc/gcc/cp/pt.c:9009
0x7a7a8d finish_template_type(tree_node*, tree_node*, int)
        ../../gcc/gcc/cp/semantics.c:3151
0x7308f4 cp_parser_template_id
        ../../gcc/gcc/cp/parser.c:15491
0x730b0f cp_parser_class_name
        ../../gcc/gcc/cp/parser.c:21949
0x72d572 cp_parser_qualifying_entity
        ../../gcc/gcc/cp/parser.c:6285
0x72d572 cp_parser_nested_name_specifier_opt
        ../../gcc/gcc/cp/parser.c:5971
0x732b23 cp_parser_simple_type_specifier
        ../../gcc/gcc/cp/parser.c:16822
0x7208ad cp_parser_type_specifier
        ../../gcc/gcc/cp/parser.c:16495
0x72f1e2 cp_parser_type_specifier_seq
        ../../gcc/gcc/cp/parser.c:20777
0x724e61 cp_parser_type_id_1
        ../../gcc/gcc/cp/parser.c:20623
0x72c4f0 cp_parser_type_id
        ../../gcc/gcc/cp/parser.c:20693
0x72c4f0 cp_parser_alias_declaration
        ../../gcc/gcc/cp/parser.c:18589
Please submit a full bug report, [etc.]

In GCC 5 and before the code was accepted.