On Tue, 19 Apr 2022 at 08:57, <language.lawyer_at_[hidden]> wrote:

> On 19/04/2022 10:37, Edward Catmur wrote:
> > On Tue, 19 Apr 2022 at 03:22, <language.lawyer_at_[hidden]> wrote:
> >
> >> On 18/04/2022 23:23, Edward Catmur wrote:
> >>> On Mon, 18 Apr 2022 at 21:13, <language.lawyer_at_[hidden]> wrote:
> >>>
> >>>> On 18/04/2022 22:57, Edward Catmur wrote:
> >>>>> I suppose that paragraph <
> >> https://eel.is/c++draft/expr.call#7.sentence-4>
> >>>> (and
> >>>>> the following Note) should be struck entirely.
> >>>> I'd say then we will not know which object [expr.prim.this]/1 speaks
> >> about
> >>>> («The keyword `this` names a pointer to the object for which an
> implicit
> >>>> object member function is invoked»)
> >>>>
> >>>
> >>> "the object for which an implicit object member function is invoked"
> >> seems
> >>> clear enough; per [expr.call]/2 it's the object expression on the LHS
> of
> >>> the postfix expression (before the '.', '->', '.*' or '->*').
> >>
> >> If it is a base-class function, the object is the corresponding base
> class
> >> subobject, isn't it?
> >>
> >
> > Yes, but that's a problem with [expr.prim.this]/1; you can't have a
> pointer
> > of base type pointing to an object of derived type. So that subclause is
> > also defective, and should have appended ", or to its base class
> subobject,
> > as appropriate".
>
> I don't understand where the defect is.
> When «the object for which function is invoked» is a base class subobject
> (and it is pointed to by `this`), there is no discrepancy between the type
> of `this` and the object's type.
> «The object for which function is invoked» does not have to be «the result
> of the object expression».
>

If it isn't (and is the base class subobject), where is that specified? Or
where should it be specified?

> As for [expr.call]/7, there's no need to specify *how* the implementation
> > is expected to come up with the value of the `this` pointer (although it
> > could be a Note).
>
> When you say that [expc.call]/2 defines the object for which the function
> is invoked, do you mean «the call is as a member of the class object
> referred to by the object expression»?
>

Yes, I think that's where the connection is made. So that's possibly a
derived class object, and it's worth explaining where the this pointer with
type pointer to base gets its value from.