[Bug c++/84630] New: internal compiler error: tree check: expected class 'type', have 'exceptional' (error_mark) in tsubst_lambda_expr, at cp/pt.c:17141

[vegard.nossum at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84630

            Bug ID: 84630
           Summary: internal compiler error: tree check: expected class
                    'type', have 'exceptional' (error_mark) in
                    tsubst_lambda_expr, at cp/pt.c:17141
           Product: gcc
           Version: 8.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vegard.nossum at gmail dot com
  Target Milestone: ---

I was quite sure I had submitted this one but I have searched and cannot see it
anywhere, my apologies if it turns out to be a duplicate.

Input:

template <typename...> struct c {
  template <const> __attribute__((noinline([] {}))) b() {}
};
c<> a;

Output:

$ xgcc -x c++ -S -
<stdin>:2:13: error: ISO C++ forbids declaration of 'parameter' with no type
[-fpermissive]
<stdin>:2:55: error: ISO C++ forbids declaration of 'b' with no type
[-fpermissive]
<stdin>: In member function 'int c< <template-parameter-1-1> >::b()':
<stdin>:2:58: warning: no return statement in function returning non-void
[-Wreturn-type]
<stdin>: In instantiation of 'struct c<>':
<stdin>:4:5:   required from here
<stdin>:2:53: internal compiler error: tree check: expected class 'type', have
'exceptional' (error_mark) in tsubst_lambda_expr, at cp/pt.c:17141
0x6602e9 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        /home/vegard/git/gcc/gcc/tree.c:9388
0x11dd0a0 tree_class_check(tree_node*, tree_code_class, char const*, int, char
const*)
        /home/vegard/git/gcc/gcc/tree.h:3255
0x11dd0a0 tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
        /home/vegard/git/gcc/gcc/cp/pt.c:17141
0x10f640b tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        /home/vegard/git/gcc/gcc/cp/pt.c:18479
0x10f408a tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        /home/vegard/git/gcc/gcc/cp/pt.c:18168
0x10bfe06 tsubst_expr(tree_node*, tree_node*, int, tree_node*, bool)
        /home/vegard/git/gcc/gcc/cp/pt.c:16973
0x1164bbf tsubst_attribute
        /home/vegard/git/gcc/gcc/cp/pt.c:10327
0x1174e7c apply_late_template_attributes
        /home/vegard/git/gcc/gcc/cp/pt.c:10428
0x117ef90 tsubst_function_decl
        /home/vegard/git/gcc/gcc/cp/pt.c:12687
0x1184e90 tsubst_template_decl
        /home/vegard/git/gcc/gcc/cp/pt.c:12804
0x1155421 tsubst_decl
        /home/vegard/git/gcc/gcc/cp/pt.c:12906
0x1105c06 tsubst(tree_node*, tree_node*, int, tree_node*)
        /home/vegard/git/gcc/gcc/cp/pt.c:13798
0x11e2760 instantiate_class_template_1
        /home/vegard/git/gcc/gcc/cp/pt.c:10743
0x11ef20b instantiate_class_template(tree_node*)
        /home/vegard/git/gcc/gcc/cp/pt.c:11041
0x138b930 complete_type(tree_node*)
        /home/vegard/git/gcc/gcc/cp/typeck.c:136
0xb38193 start_decl_1(tree_node*, bool)
        /home/vegard/git/gcc/gcc/cp/decl.c:5244
0xc1a64f start_decl(cp_declarator const*, cp_decl_specifier_seq*, int,
tree_node*, tree_node*, tree_node**)
        /home/vegard/git/gcc/gcc/cp/decl.c:5207
0xfa251c cp_parser_init_declarator
        /home/vegard/git/gcc/gcc/cp/parser.c:19589
0xfa8357 cp_parser_simple_declaration
        /home/vegard/git/gcc/gcc/cp/parser.c:13061
0xfae548 cp_parser_block_declaration
        /home/vegard/git/gcc/gcc/cp/parser.c:12879

$ xgcc --version
xgcc (GCC) 8.0.1 20180228 (experimental)

Built from git fd1990b25777e5f1307eac1447e8fb5fefe747b4 (r258063).

7.3.0 says:

<source>:2:13: error: ISO C++ forbids declaration of 'parameter' with no type
[-fpermissive]
   template <const> __attribute__((noinline([] {}))) b() {}
             ^~~~~
<source>:2:55: error: ISO C++ forbids declaration of 'b' with no type
[-fpermissive]
   template <const> __attribute__((noinline([] {}))) b() {}
                                                       ^
<source>:1: confused by earlier errors, bailing out
Compiler returned: 1

Test case was reduced by C-Reduce.