Re: [PATCH] dissect: add support for _Generic

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

On Thu, Jul 30, 2020 at 05:08:37PM +0200, Oleg Nesterov wrote:
> On 07/29, Luc Van Oostenryck wrote:
> > The returned type will just be
> > quite arbitrary, but I don't know how much it matters.
> 
> Of course. And this is not good. For example:
> 
> 	void func(void)
> 	{
> 		struct B *b; struct C *c; struct D *d;
> 		_Generic(a,
> 			int:		b,
> 			void*:		c,
> 			default:	d
> 		) ->mem++;
> 	}
> 
> output:
> 
>    1:6                    def   f func                             void ( ... )
>    3:18  func             def . v b                                struct B *
>    3:31  func             def . v c                                struct C *
>    3:44  func             def . v d                                struct D *
>    4:18  func             ---   v a                                bad type
>    5:33  func             --m . v b                                struct B *
>    6:33  func             --m . v c                                struct C *
>    7:33  func             --m . v d                                struct D *
>    8:11  func             -m-   m D.mem                            bad type
> 
> But I do not know how to improve it without serious complications, and

Are you thinking about calling evaluate_symbol_list() or about
something else? What kind of complications?

> (so far) I think it doesn't worth the effort.

Yes, _Generic() clearly makes things a bit more complicated here.
Same for __auto_type, which is not yet used by the kernel but will
probably be soon.

-- Luc