[Bug c/102346] New: Missing warning for array bounds

[fredrik.hederstierna@securitas-direct.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102346

            Bug ID: 102346
           Summary: Missing warning for array bounds
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fredrik.hederstierna@securitas-direct.com
  Target Milestone: ---

Created attachment 51467
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51467&action=edit
example test file

There is no warning for array bounds overrun with this code.


Compiled with Gcc-11.2.0

        gcc -o test string_array_concat.c -W -Wall -Wextra -Warray-bounds=2 -O2


Gives other warning from printf usage only

In file included from /usr/include/stdio.h:867,
                 from string_array_concat.c:1:
In function ‘printf’,
    inlined from ‘main’ at string_array_concat.c:13:3:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:107:10: warning: ‘%s’ directive
argument is null [-Wformat-overflow=]
  107 |   return __printf_chk (__USE_FORTIFY_LEVEL - 1, __fmt, __va_arg_pack
());
      |         
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Though eg CLANG does give warning for this:

fredrik@deadbolt ~/test$ clang -o test string_array_concat.c

string_array_concat.c:13:30: warning: array index 1 is past the end of the
array (which contains 1 element) [-Warray-bounds]
  printf("item_at_1 = %s\n", item[1]);
                             ^    ~
string_array_concat.c:3:1: note: array 'item' declared here
static const char *item[1] = { "TestString" };
^
string_array_concat.c:15:10: warning: array index 1 is past the end of the
array (which contains 1 element) [-Warray-bounds]
  return item[1];
         ^    ~
string_array_concat.c:3:1: note: array 'item' declared here
static const char *item[1] = { "TestString" };
^
2 warnings generated.