[Bug c/59520] New: a possible inconsistency in error diagnostics with "-pedantic -std=c99"

["su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59520

            Bug ID: 59520
           Summary: a possible inconsistency in error diagnostics with
                    "-pedantic -std=c99"
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu

I wonder whether or not the following examples illustrate an unintended
inconsistency with error diagnostics in GCC. 

In particular, should the diagnostic message be a warning for error3.c rather
than an error as shown below?  

error3.c:1:5: error: zero or negative size array âaâ
 int a[] = {}; 
     ^

---------------

$ gcc-trunk -pedantic -std=c99 -c error1.c
error1.c:1:12: warning: ISO C forbids empty initializer braces [-Wpedantic]
 int a[1] = {};
            ^
$ clang-trunk -pedantic -std=c99 -c error1.c
error1.c:1:12: warning: use of GNU empty initializer extension
[-Wgnu-empty-initializer]
int a[1] = {};
           ^
1 warning generated.
$ cat error1.c
int a[1] = {};
$ 

---------------

$ gcc-trunk -pedantic -std=c99 -c error2.c
error2.c:1:5: warning: array âaâ assumed to have one element [enabled by
default]
 int a[];
     ^
$ clang-trunk -pedantic -std=c99 -c error2.c
error2.c:1:5: warning: tentative array definition assumed to have one element
int a[];
    ^
1 warning generated.
$ cat error2.c
int a[];
$ 

---------------

$ gcc-trunk -pedantic -std=c99 -c error3.c
error3.c:1:11: warning: ISO C forbids empty initializer braces [-Wpedantic]
 int a[] = {}; 
           ^
error3.c:1:5: error: zero or negative size array âaâ
 int a[] = {}; 
     ^
$ clang-trunk -pedantic -std=c99 -c error3.c
error3.c:1:11: warning: use of GNU empty initializer extension
[-Wgnu-empty-initializer]
int a[] = {}; 
          ^
error3.c:1:11: warning: zero size arrays are an extension [-Wzero-length-array]
2 warnings generated.
$ cat error3.c
int a[] = {}; 
$