Re: [PATCH] Use positional_argument in callback_only attribute handler

On Mon, Aug 03, 2026 at 04:13:02PM +0200, Josef Melcr wrote:
> This patch replaces some of the manual bounds checking done in the
> callback_only attribute handler with calls to positional_argument.
> Since positional_argument issues warnings and the attribute handler
> issues errors, I decided to downgrade the errors to warnings for
> consistency.
> 
> gcc/c-family/ChangeLog:
> 
> 	* c-attribs.cc (handle_callback_only_attribute): Use
> 	positional_argument for bounds checking in callback_only
> 	attribute handler, downgrade errors to warnings for
> 	consistency.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.dg/attr-callback.c: Expect warnings instead of errors,
> 	adjust expected messages.
> 
> Signed-off-by: Josef Melcr <[email protected]>

LGTM, except a nit.

>        if (!types_compatible_p (expected_type, arg_type))
>  	{
> -	  error_at (DECL_SOURCE_LOCATION (decl),
> -		    "argument type at index %d is not compatible with callback "
> -		    "argument type at index %d",
> -		    arg_idx + 1, curr + 1);
> +	  warning_at (
> +	    DECL_SOURCE_LOCATION (decl), OPT_Wattributes,
> +	    "argument type at index %d is not compatible with callback "
> +	    "argument type at index %d",
> +	    arg_idx + 1, curr + 1);

Please avoid formatting like this unless really necessary (too long
function name and no way to easily fit it).
In this case,
	  warning_at (DECL_SOURCE_LOCATION (decl), OPT_Wattributes,
		      "argument type at index %d is not compatible with "
		      "callback argument type at index %d",
		      arg_idx + 1, curr + 1);
fits just fine.

	Jakub