On Thu, May 5, 2022 at 11:23 AM Aaron Ballman <aaron_at_[hidden]> wrote:
>
> On Thu, May 5, 2022 at 9:35 AM Jₑₙₛ Gustedt via Liaison
> <liaison_at_[hidden]> wrote:
> >
> > Aaron,
> >
> > on Thu, 5 May 2022 09:01:47 -0400 you (Aaron Ballman via Liaison
> > <liaison_at_[hidden]>) wrote:
> >
> > > 6.7.2.1p15: An unnamed member whose type specifier is a structure
> > > specifier with no tag is called an anonymous structure; an unnamed
> > > member whose type specifier is a union specifier with no tag is called
> > > an anonymous union. The members of an anonymous structure or union are
> > > considered to be members of the containing structure or union, keeping
> > > their structure or union layout. This applies recursively if the
> > > containing structure or union is also anonymous.
> >
> > > ...
> >
> > > I *think* what may have been intended is for 6.7.2.1p15 to instead say
> > > something along the lines of: ... The members of an anonymous
> > > structure or union are considered to be members of the containing
> > > structure or union, keeping their structure or union layout <ins>and
> > > the qualifiers specified for the unnamed member</ins>. ...
> >
> > This would have made that clearer, but I think that this already
> > follows, anyhow. The type of `bar` is indeed `int const` and not
> > `int`. The `const` of the surrounding structure comes from the part in
> > 6.3.2.1p1 that you cited
> >
> > ... and if it is a structure or union, does not have any
> > member (including, recursively, any member or element of all
> > contained aggregates or unions) with a const-qualified type.
> >
> > This specification doesn't exclude unnamed members, and so
> > `<anonymous>.bar` is not a modifiable lvalue.
>
> I like that reading, thank you for this observation!

Actually, thinking on this a bit more, I'm not certain this is
correct. The modifiable lvalue in question is the left operand of the
assignment operator, and the left operand is the result of the member
access expression, which is an `int` which is not itself const
qualified.

~Aaron

>
> > But you are right that this could all be clearer by pushing it on the
> > syntax somehow:
> >
> > If a member is an agreate or union type and is `const` or
> > `volatile` qualified, all of its members, even recursively are
> > so qualified.
>
> Yeah, I think we could make this a bit more clear editorially if we
> thought that was a good idea.
>
> ~Aaron
>
> > Jₑₙₛ
> >
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