Re: [ C++ ] [ PATCH ] [ RFC ] p1301 - [[nodiscard("should have a reason")]]

[Jason Merrill <jason at redhat dot com>]

On 10/15/19 8:31 PM, JeanHeyd Meneide wrote:
> Attached is a patch for p1301 that improves in the way Jason Merrill
> specified earlier
> (https://gcc.gnu.org/ml/gcc-patches/2019-09/msg00858.html)

Great, thanks!

This mail is missing ChangeLog entries.  My guess is that you're using 
git diff to create the patch file; git show or (even better) git 
format-patch will also include the commit message.

> +/* Check that the attribute ATTRIBU,TE appears at most once in the

Stray added ,

> -  else if (TREE_CODE (expr) == TARGET_EXPR
> -	   && lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type)))
> +  else if (TREE_CODE (expr) == TARGET_EXPR)
>      {
>        /* The TARGET_EXPR confuses do_warn_unused_result into thinking that the
>  	 result is used, so handle that case here.  */
> -      if (fn)
> +      if (lookup_attribute ("warn_unused_result", TYPE_ATTRIBUTES (type)))
...
> +      else if ((attr = lookup_attribute ("nodiscard", TYPE_ATTRIBUTES (type))))

The first two if/else should have already handled nodiscard; this else 
was only intended to handle cases where warn_unused_result wants a 
warning and nodiscard doesn't, i.e. when there's an explicit cast to 
void.  We shouldn't need to change anything here.

Jason