[Bug c/59801] New: GCC does not warn on unused global variable

["chengniansun at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59801

            Bug ID: 59801
           Summary: GCC does not warn on unused global variable
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com

Created attachment 31829
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31829&action=edit
the test case to trigger the bug.

I used the following command 

$gcc -Wall -Wextra -pedantic -std=c11 -c unused-var.c

And GCC outputs no warnings.


However in the source file unused-var.c, the last global variable "g_1853" is
NOT used. 

//////////////////////////////  Start of the source file /////////////
/**
 * compile this program with the following command
 *
 * gcc -c -pedantic -std=c11 -Wall -Wextra unused-var.c
 */


static int g_37 = (-1L);
static int *g_187 = &g_37;

/**
 * this variable will NOT be reported although it is NOT used.
 */
static int ** volatile g_1853 = &g_187;/* VOLATILE GLOBAL g_1853 */

//////////////////////////////  End of the source file /////////////


The Gcc version is 4.9.0, built on 01/09/2014
gcc (GCC) 4.9.0 20140109 (experimental)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.