Re: [PATCH] add missing attribute nonnull to stdio functions (PR 78673 and 17308)

[Jakub Jelinek <jakub at redhat dot com>]

On Wed, Dec 07, 2016 at 08:24:33PM -0700, Martin Sebor wrote:
> @@ -8622,15 +8635,17 @@ rewrite_call_expr (location_t loc, tree exp, int skip, tree fndecl, int n, ...)
>  }
>  
>  /* Validate a single argument ARG against a tree code CODE representing
> -   a type.  */
> +   a type.  When NONNULL is true consider a pointer argument valid only
> +   if it's non-null.  Return true when argument is valid.  */
>  
>  static bool
> -validate_arg (const_tree arg, enum tree_code code)
> +validate_arg (const_tree arg, enum tree_code code, bool nonnull /*= false*/)
>  {
>    if (!arg)
>      return false;
>    else if (code == POINTER_TYPE)
> -    return POINTER_TYPE_P (TREE_TYPE (arg));
> +    return POINTER_TYPE_P (TREE_TYPE (arg))
> +      && (!nonnull || !integer_zerop (arg));
>    else if (code == INTEGER_TYPE)
>      return INTEGRAL_TYPE_P (TREE_TYPE (arg));
>    return code == TREE_CODE (TREE_TYPE (arg));

This is badly formatted, it would need to be
    return (POINTER_TYPE_P (TREE_TYPE (arg))
	    && (!nonnull || !integer_zerop (arg)));
but more importantly, we have 45 validate_arg calls that really don't care
about the nonnull stuff and a single one that cares.  I think
it would be better to revert the validate_arg changes and do:
	case POINTER_TYPE:
	  /* The actual argument must be nonnull when either the whole
	     called function has been declared nonnull, or when the formal
	     argument corresponding to the actual argument has been.  */
	  if (argmap)
	    nonnull = bitmap_empty_p (argmap) || bitmap_bit_p (argmap, argno);
	  arg = next_const_call_expr_arg (&iter);
	  if (!validate_arg (arg, code) || (nonnull && !integer_zerop (arg)))
	    goto end;
	  break;
	default:
	  /* If no parameters remain or the parameter's code does not
	     match the specified code, return false.  Otherwise continue
	     checking any remaining arguments.  */
	  arg = next_const_call_expr_arg (&iter);
	  if (!validate_arg (arg, code, nonnull))
	    goto end;
	  break;

	Jakub