I know this is an old bug report, but I just realized it got a response,
and it seems like the behavior hasn't changed.

On Thu, Dec 3, 2020 at 3:07 AM Lars Ingebrigtsen <larsi@gnus.org> wrote:

> Gulshan Singh <gsingh2011@gmail.com> writes:
>
> > In c-mode (and all derivatives), the following code has the wrong
> > syntactic information (at least, in my opinion):
> >
> > foo(bar
> >     .baz()
> >     .qux());
> >
> > Putting point at `.baz()` and pressing C-c C-s shows it as an
> > `arglist-cont-nonempty`, when I'd expect it to be a
> > `statement-cont`. This causes the code to have the wrong indentation, as
> > above I would like to have the continued statements to be indented one
> > c-basic-offset, not aligned to the opening brace.
>
> (This bug report unfortunately got no response at the time.)
>
> I'm not sure how that should be indented, really -- the current
> indentation looks reasonable to me, I think?
>

It's definitely reasonable, but it's not what I'd prefer, which would be
this:

foo(bar
      .baz()
      .qux());

`.baz()` and `.qux()` are indented two spaces (my value for
`c-basic-offset`) from the start of `bar`, as opposed to aligned with
`bar`. This matches what happens if the call to `foo` isn't there:

bar
  .baz()
  .qux();

In any case, regardless of what indentation one would prefer for this case,
the issue remains that `c-show-syntactic-information` should be showing
`statement-cont` instead of `arglist-cont-nonempty` at `.baz()`.