Re: c/2591: variable expression erroneously allowed to dimension array

Re: c/2591: variable expression erroneously allowed to dimension array

[Toshi Morita]

The following reply was made to PR c/2591; it has been noted by GNATS.

From: Toshi Morita <tm2@best.com>
To: allen.everhart@marcgs.com
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c/2591: variable expression erroneously allowed to dimension array
Date: Thu, 19 Apr 2001 15:58:21 -0700 (PDT)

 > 
 > >Number:         2591
 > >Category:       c
 > >Synopsis:       variable expression erroneously allowed to dimension array
 > >Confidential:   no
 > >Severity:       serious
 > >Priority:       high
 > >Responsible:    unassigned
 > >State:          open
 > >Class:          accepts-illegal
 > >Submitter-Id:   net
 > >Arrival-Date:   Thu Apr 19 14:26:00 PDT 2001
 > >Closed-Date:
 > >Last-Modified:
 > >Originator:     Allen Everhart
 > >Release:        gcc version 2.8.1
 ...
 > int printf( char *, ... ) ;
 > int i=1 ;
 > 
 > int main()
 > {
 >         char buff[i] ; /* variable expression allowed to dimension array */ 
 > 
 >         buff[0] = 'f' ;
 >         buff[1] = 'o' ;
 >         buff[2] = 'o' ;
 >         buff[3] = '\0' ;
 >         return printf(  "%s %d\n", buff, sizeof(buff) ) ;
 > }
 
 This is a GNU C extension. If you want to disable GNU C extensions, you should
 use -pedantic -ansi, I believe.
 
 Toshi
 

c/2591: variable expression erroneously allowed to dimension array

[allen.everhart]

>Number:         2591
>Category:       c
>Synopsis:       variable expression erroneously allowed to dimension array
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    unassigned
>State:          open
>Class:          accepts-illegal
>Submitter-Id:   net
>Arrival-Date:   Thu Apr 19 14:26:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Allen Everhart
>Release:        gcc version 2.8.1
>Organization:
>Environment:
AIX 4.2 also is accepted by CodeSorcery
/marces/gnu/lib/gcc-lib/powerpc-ibm-aix4.2.1.0/2.8.1/specs
>Description:
An automatic array is erroneously allowed to be dimensioned by a variable expression. This is an ansi violation and highly nonportable to other ansi compilers.
>How-To-Repeat:
gcc -Wall -ansi variabledimensionedarray.c
>Fix:
compile with xlc and fix syntax errors.
>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="variabledimensionedarray.txt"
Content-Disposition: inline; filename="variabledimensionedarray.txt"

int printf( char *, ... ) ;
int i=1 ;

int main()
{
        char buff[i] ; /* variable expression allowed to dimension array */ 

        buff[0] = 'f' ;
        buff[1] = 'o' ;
        buff[2] = 'o' ;
        buff[3] = '\0' ;
        return printf(  "%s %d\n", buff, sizeof(buff) ) ;
}