Re: [PLUG] C question: struct pointer error

["mike.h" <mike.h@stemik.com>]

Jeff,

Using a forward declaration, this compiled & ran without error or
warning:

struct bar;   /* forward declaration */
int foo(struct bar *b);
typedef struct bar {
   int a;
 } Bar;

int main(){
 struct  bar *b;    
 Bar *b2;
 foo(b);
 foo(b2);
 return 0;
}

int foo(struct bar *b){
  return 0;
}

On Sun, 2002-12-08 at 16:59, Jeff Abrahamson wrote:
> I wonder if someone can help me see what I'm missing.
> 
> The following code snippet yields a warning and an error. I don't
> think it should. Am I confused, or is gcc?
> 
>     int foo(struct bar *b);
> 
>     typedef struct bar {
> 	    int a;
>     } Bar;
> 
>     foo(Bar *b)
>     {
> 	    return 0;
>     }
> 
>  jeff@diderot:scratch $ gcc  -Wall -c struct2.c
>  struct2.c:1: warning: `struct bar' declared inside parameter list
>  struct2.c:1: warning: its scope is only this definition or declaration, which is probably not what you want.
>  struct2.c:8: warning: return-type defaults to `int'
>  struct2.c:8: conflicting types for `foo'
>  struct2.c:1: previous declaration of `foo'
>  jeff@diderot:scratch $ 
> 
> At line 1, the size of the structure is not needed, so the declaration
> should be ok by my reading of K&R. Then at line 8, Bar is a synonym
> for struct bar, so it should be ok, again as per my understanding of
> K&R (by which I mean the ANSI C version, of course).
> 
>  jeff@diderot:scratch $ gcc -v
>  Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs
>  gcc version 2.95.4 20011002 (Debian prerelease)
>  jeff@diderot:scratch $ 
> 
> -- 
>  Jeff
> 
>  Jeff Abrahamson  <http://www.purple.com/jeff/>
>  GPG fingerprint: 1A1A BA95 D082 A558 A276  63C6 16BF 8C4C 0D1D AE4B


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