Re: [PATCH v3 1/2] c++: Initial support for P0847R7 (Deducing This) [PR102609]

[Jason Merrill <jason@redhat.com>]

On 11/19/23 13:36, waffl3x wrote:
> I'm having trouble fixing the error for this case, the control flow
> when the functions are overloaded is much more complex.
> 
> struct S {
>    void f(this S&) {}
>    void f(this S&, int)
> 
>    void g() {
>      void (*fp)(S&) = &f;
>    }
> };
> 
> This seemed to have fixed the non overloaded case, but I'm also not
> very happy with it, it feels kind of icky. Especially since the expr's
> location isn't available here, although, it just occurred to me that
> the expr's location is probably stored in the node.
> 
> typeck.cc:cp_build_addr_expr_1
> ```
>      case BASELINK:
>        arg = BASELINK_FUNCTIONS (arg);
>        if (DECL_XOBJ_MEMBER_FUNC_P (
>          {
>            error ("You must qualify taking address of xobj member functions");
> 	  return error_mark_node;
>          }

The loc variable was set earlier in the function, you can use that.

The overloaded case we want to handle here in 
resolve_address_of_overloaded_function:

>   if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn)
>       && !(complain & tf_ptrmem_ok) && !flag_ms_extensions)
>     {
>       static int explained;
> 
>       if (!(complain & tf_error))
>         return error_mark_node;
> 
>       auto_diagnostic_group d;
>       if (permerror (input_location, "assuming pointer to member %qD", fn)
>           && !explained)
>         {
>           inform (input_location, "(a pointer to member can only be "
>                   "formed with %<&%E%>)", fn);
>           explained = 1;
>         }
>     }

Jason