[Bug c/81631] New: -Wcast-qual false positive for pointer to array

["gcc17 at cwde dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81631

            Bug ID: 81631
           Summary: -Wcast-qual false positive for pointer to array
           Product: gcc
           Version: 7.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gcc17 at cwde dot de
  Target Milestone: ---

Hi,

------
typedef int footype[6];

extern void const * bar;

void baz(void)
{
  footype const * x;
  x = (footype const *) bar;
}
------

with -Wcast-qual, this yields

------
$ gcc -Wcast-qual -c foo.c
foo.c:12:7: warning: cast discards 'const' qualifier from pointer target type
[-Wcast-qual]
   x = (footype const *) bar;
       ^
------

If "footype" is any other type than an array, I don't get the warning. I tested
gcc 4.5.1, 6.3.0, 7.1.0, on cygwin and Debian, all show this behavior. clang
doesn't warn.