RE: [avr-gcc-list] Deprecated warning on 3.4.1

[Dave Hylands]

The 

        *dst++ = *src++

Is fairly traditional code used inside a copy loop. So I think that the
original intent was this:

        *dst++ = *src;
        src++;

So the original binding was correct.

I think that this needs to be rewritten as:

        *dst = *(unsigned char *)src;
        src = (whatever type src is)((unsigned char *)src + 1);

The original form was equivalent to:

        (unsigned char *)src = (unsigned char *)src + 1;

Compiling this snippet (with -O)

  void copy( unsigned char *dst, void *src )
  {
     while ( *(unsigned char *)src )
     {
        *dst++ = *(((unsigned char *)src)++);
     }
  }

Produces identical assembly output (minus the warning) to this version
(also using -O):

  void copy( unsigned char *dst, void *src )
  {
     while ( *(unsigned char *)src )
     {
        *dst++ = *(unsigned char *)src;
        src = (unsigned char *)src + 1;
     }
  }

So we can be sure that they are in fact equivalent.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/ 

> ++ binds tighter than *, so you've done:
> 
>    dereference the incremented cast of src to unsigned char *
> 
> (and so you are indeed using the result of a cast as an lvalue)
> 
> You presumably wanted
> 
>    (*((unsigned char *)src))++
> 
> which is
> 
>    increment the dereference of the cast of src to unsigned char *
> 
> David Gay
> 
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