Re: [PATCH] c: support attribs starting with '_'

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Oct 05, 2022 at 01:49:40PM +0200, Martin Liška wrote:
> 	PR c/107156
> 
> gcc/ChangeLog:
> 
> 	* attribs.h (lookup_attribute_by_prefix): Support attributes
> 	starting with underscore (like _noreturn, or __Noreturn).

There are no _noreturn or __Noreturn attributes, there is just
_Noreturn.
And, the assert is useful to catch that non-canonicalized attributes
don't make it into the attribute lists.
Now that we have the first attribute that starts with an underscore
in canonicalized form (do we accept ___Noreturn__ attribute too, perhaps
we shouldn't?), I'd say instead of removing the assert it should verify
	gcc_checking_assert (attr_len == 0 || p[0] != '_'
			     || (ident_len > 1 && p[1] != '_'));
?
> ---
>  gcc/attribs.h | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/gcc/attribs.h b/gcc/attribs.h
> index b2836560fc2..706d35e63d8 100644
> --- a/gcc/attribs.h
> +++ b/gcc/attribs.h
> @@ -274,8 +274,6 @@ lookup_attribute_by_prefix (const char *attr_name, tree list)
>  	    }
>  
>  	  const char *p = IDENTIFIER_POINTER (name);
> -	  gcc_checking_assert (attr_len == 0 || p[0] != '_');
> -
>  	  if (strncmp (attr_name, p, attr_len) == 0)
>  	    break;
>  
> -- 
> 2.37.3

	Jakub