[Bug c/79758] New: ICE: tree check: expected class 'type', have 'exceptional' (error_mark) in store_parm_decls_oldstyle, at c/c-decl.c:8973

[gerhard.steinmetz.fortran@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79758

            Bug ID: 79758
           Summary: ICE: tree check: expected class 'type', have
                    'exceptional' (error_mark) in
                    store_parm_decls_oldstyle, at c/c-decl.c:8973
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gerhard.steinmetz.fortran@t-online.de
  Target Milestone: ---

With invalid code on x86_64 GNU/Linux down to at least 4.8
(configured with --enable-checking=yes) :


$ cat z1.c
void fn1 (int[a]) { };
void fn1 (b) { };


$ gcc-7-20170226 -c z1.c
z1.c:1:15: error: 'a' undeclared here (not in a function)
 void fn1 (int[a]) { };
               ^
z1.c: In function 'fn1':
z1.c:1:14: error: parameter name omitted
 void fn1 (int[a]) { };
              ^
z1.c: At top level:
z1.c:2:6: error: redefinition of 'fn1'
 void fn1 (b) { };
      ^~~
z1.c:1:6: note: previous definition of 'fn1' was here
 void fn1 (int[a]) { };
      ^~~
z1.c: In function 'fn1':
z1.c:2:6: warning: type of 'b' defaults to 'int' [-Wimplicit-int]
 void fn1 (b) { };
      ^~~
z1.c:2:1: internal compiler error: tree check: expected class 'type', have
'exceptional' (error_mark) in store_parm_decls_oldstyle, at c/c-decl.c:8973
 void fn1 (b) { };
 ^~~~
0xea3607 tree_class_check_failed(tree_node const*, tree_code_class, char
const*, int, char const*)
        ../../gcc/tree.c:9866
0x672ead tree_class_check(tree_node*, tree_code_class, char const*, int, char
const*)
        ../../gcc/tree.h:3187
0x672ead store_parm_decls_oldstyle
        ../../gcc/c/c-decl.c:8973
0x672ead store_parm_decls()
        ../../gcc/c/c-decl.c:9147
0x6d05af c_parser_declaration_or_fndef
        ../../gcc/c/c-parser.c:2074
0x6d87fb c_parser_external_declaration
        ../../gcc/c/c-parser.c:1468
0x6d9259 c_parser_translation_unit
        ../../gcc/c/c-parser.c:1348
0x6d9259 c_parse_file()
        ../../gcc/c/c-parser.c:18173
0x737b02 c_common_parse_file()
        ../../gcc/c-family/c-opts.c:1107