Re: c/10170: Is this a bug of GCC? or it's a C syntax

Re: c/10170: Is this a bug of GCC? or it's a C syntax

[Kinh Nguyen]

The following reply was made to PR c/10170; it has been noted by GNATS.

From: Kinh Nguyen <xkinh@yahoo.com>
To: bangerth@dealii.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
  nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c/10170: Is this a bug of GCC? or it's a C syntax
Date: Thu, 20 Mar 2003 13:21:37 -0800 (PST)

 I totally agree with you about the C syntax and the
 way GCC handles it.  I just hope the GCC would detect
 and give a warning so life would be easier for C
 programmers.  I made a mistake in typing when I 
 modified a big program. It gave me a lot of head-ache
 to figure out the problem.
 Thanks
 Kinh
 
 --- bangerth@dealii.org wrote:
 > Synopsis: Is this a bug of GCC? or it's a C syntax
 > 
 > State-Changed-From-To: open->closed
 > State-Changed-By: bangerth
 > State-Changed-When: Thu Mar 20 18:44:53 2003
 > State-Changed-Why:
 >     Your code is perfectly legal: you take the
 > address of a
 >     function and in the if-statement, it is
 > implicitly compared
 >     against zero. Since the function's address is
 > non-zero, 
 >     the printf-branch is executed.
 >     
 >     Other compilers will certainly not give you
 > errors on this
 >     code, since it is legal. They may give you
 > warnings, as
 >     icc does here, for example:
 >     g/x> icc x.c
 >     x.c(4): warning #279: controlling expression is
 > constant
 >         if (alwayzero)
 >             ^
 >     
 >     W.
 > 
 >
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10170
 
 
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Re: c/10170: Is this a bug of GCC? or it's a C syntax

[bangerth]

Synopsis: Is this a bug of GCC? or it's a C syntax

State-Changed-From-To: open->closed
State-Changed-By: bangerth
State-Changed-When: Thu Mar 20 18:44:53 2003
State-Changed-Why:
    Your code is perfectly legal: you take the address of a
    function and in the if-statement, it is implicitly compared
    against zero. Since the function's address is non-zero, 
    the printf-branch is executed.
    
    Other compilers will certainly not give you errors on this
    code, since it is legal. They may give you warnings, as
    icc does here, for example:
    g/x> icc x.c
    x.c(4): warning #279: controlling expression is constant
        if (alwayzero)
            ^
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10170

c/10170: Is this a bug of GCC? or it's a C syntax

[xkinh]

>Number:         10170
>Category:       c
>Synopsis:       Is this a bug of GCC? or it's a C syntax
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Mar 20 18:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Kinh Nguyen
>Release:        3.2.2 and earlier
>Organization:
>Environment:
Linux, Sun
>Description:
compile the following program and run it.  Is it a GCC bug or
it's a c syntax? (I'm not sure but other compilers give
an error message).

#include <stdio.h>
int alwayzero();
main(){
  if (alwayzero) 
    printf("Is this a GCC bug or it's the C syntax\n");
}
int alwayzero() {return 0;}
>How-To-Repeat:
Try to compile and run the program.  Other compile will give error messages
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: