[Bug c/71266] New: gcc ICE on x86_64-linux-gnu in "store_parm_decls_oldstyle"

[helloqirun at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71266

            Bug ID: 71266
           Summary: gcc ICE on x86_64-linux-gnu in
                    "store_parm_decls_oldstyle"
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: helloqirun at gmail dot com
  Target Milestone: ---

The following invalid code causes an ICE when compiled with the current gcc
trunk on x86_64-linux-gnu in both 32-bit and 64-bit modes. 

It appears to be a 7 regression.

$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/absozero/trunk/root-gcc/libexec/gcc/x86_64-pc-linux-gnu/7.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc/configure --prefix=/home/absozero/trunk/root-gcc
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 7.0.0 20160524 (experimental) [trunk revision 236651] (GCC) 

$ gcc-trunk abc.c
abc.c:1:8: warning: return type defaults to ‘int’ [-Wimplicit-int]
 extern fn1 ( a ) enum b { a } ; { }
        ^~~
abc.c: In function ‘fn1’:
abc.c:1:18: warning: empty declaration
 extern fn1 ( a ) enum b { a } ; { }
                  ^~~~
abc.c:1:27: error: ‘a’ declared as a non-parameter
 extern fn1 ( a ) enum b { a } ; { }
                           ^
abc.c:1:27: internal compiler error: tree check: expected parm_decl, have
const_decl in store_parm_decls_oldstyle, at c/c-decl.c:8826
0xe2fc0c tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        ../../gcc/gcc/tree.c:9753
0x672678 tree_check(tree_node*, char const*, int, char const*, tree_code)
        ../../gcc/gcc/tree.h:3030
0x672678 store_parm_decls_oldstyle
        ../../gcc/gcc/c/c-decl.c:8826
0x672678 store_parm_decls()
        ../../gcc/gcc/c/c-decl.c:8905
0x6c7e27 c_parser_declaration_or_fndef
        ../../gcc/gcc/c/c-parser.c:2095
0x6d37bd c_parser_external_declaration
        ../../gcc/gcc/c/c-parser.c:1549
0x6d41e9 c_parser_translation_unit
        ../../gcc/gcc/c/c-parser.c:1430
0x6d41e9 c_parse_file()
        ../../gcc/gcc/c/c-parser.c:17914
0x736a12 c_common_parse_file()
        ../../gcc/gcc/c-family/c-opts.c:1064
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.


$ cat abc.c
extern fn1 ( a ) enum b { a } ; { }