On Mon, May 4, 2026 at 7:20 AM Markus Armbruster <[email protected]> wrote:
>
> I'm feeling dense again.  Please be patient with me.

It's okay, this is a complex one. This is part of the reason for
pursuing strict ordering to begin with: the insertion algorithm is
complex and ugly.

>
> John Snow <[email protected]> writes:
>
> > A forthcoming patch removes the implicit PLAIN section that always
> > starts a QAPIDoc section list. Further future changes begin converting
> > "PLAIN" sections to "INTRO" sections. To accommodate this, the insertion
> > algorithm that places stub and dummy members must be adjusted to cope.
>
> What are the stub and dummy members?

"stub" - undocumented members.
"dummy" - placeholder section named q_dummy that causes "The members
of ..." references to be printed in the rendered documentation.

>
> > This algorithm can handle zero-or-more PLAIN *or* INTRO sections at the
> > beginning of a QAPIDoc object.
>
> The revised algorithm, I presume.
>
> What's the structure of its valid input before and after this patch?

Before: Plain EverythingElse?
After: (Plain* | Intro*) EverythingElse?

Where EverythingElse may never start with "Intro", and may contain
"Plain" but not as the first token when following a Plain section from
the prior production. (Because contiguous plain sections are merged by
the parser into one section.)

This is to allow a gradual conversion. Once everything is fully
converted, and especially after "details" is introduced and the strict
ordering is enforced, this is tightened down considerably to: Intro?
EverythingElse?

where EverythingElse may no longer contain Plain (It is removed), may
never contain Intro, and may only contain one Details section in the
appropriate position (Near the end, before Since.)

More or less: this patch removes the assumption that every QAPIDoc
starts with exactly one Plain section and allows it to cope with any
number of Intro/Plain sections at the beginning, but makes no change
to what the parser actually produces or accepts. In effect, we go
from:

Plain EverythingElse

to, in the next patch:

Plain? EverythingElse

then as the conversion continues, one of these two:

Intro Plain? EverythingElse? (Without converted intro)
Intro EverythingElse? (With converted intro)

... This entire insertion algorithm gets to be removed once we enforce
strict ordering, because we can insert directly to the correct
position in the list thereafter. So, it is only a temporary complexity
that exists for the sake of gradual conversion and piecemeal list
review of each QAPI module.

>
> > Since we have three places that need to insert stub members, take the
> > opportunity to unify and deduplicate this code.
>
> Three?  I can only see two: Transmogrifier.visit_sections() and
> QAPIDoc.connect_member().

Bad wording on my part again. ensure_returns also inserts stub
*sections*, not "members", sorry.

>
> >
> > Signed-off-by: John Snow <[email protected]>
> > ---
> >  docs/sphinx/qapidoc.py | 36 ++++++++---------
> >  scripts/qapi/parser.py | 90 +++++++++++++++++++++++++++---------------
> >  2 files changed, 75 insertions(+), 51 deletions(-)
> >
> > diff --git a/docs/sphinx/qapidoc.py b/docs/sphinx/qapidoc.py
> > index 1f7c15b7075..70ab9cdc214 100644
> > --- a/docs/sphinx/qapidoc.py
> > +++ b/docs/sphinx/qapidoc.py
> > @@ -349,30 +349,32 @@ def _get_target(
> >                  )
> >
> >      def visit_sections(self, ent: QAPISchemaDefinition) -> None:
> > +        # Generate a placeholder right after the member section(s) which
> > +        # will be used to generate documentation for "The members of..."
> > +        # pointers in the rendered document.
> > +        # This is a temporary hack until the inliner is merged.
> > +        if ent.doc:
> > +            ent.doc.append_member_stub(
> > +                QAPIDoc.ArgSection(
> > +                    ent.doc.info, QAPIDoc.Kind.MEMBER, "q_dummy"
> > +                )
> > +            )
> > +
>
> This hack is of the nastier sort: passing a QAPISchema to the doc
> generator modifies it.
>
> Would it be possible to add this dummy always in QAPISchema?  Any
> drawbacks?

Well...

I didn't like the idea of generating "q_dummy" stubs inside the
parser, as it is an implementation detail of qapidoc. Though as you
note, this leaks it back out anyway.

Here's my argument: the entire "q_dummy" thing goes away with the
inliner anyway, which is what I am actively working towards, and this
ugliness goes away entirely either way: we do not need q_dummy, we do
not need member pointer stubs, we will not need to modify the caller's
section list.

I found this easier to do, despite the ugliness. Also consider that in
this case, we are building an isolated schema directly inside of the
Sphinx process anyway, so we are spiritually already "modifying our
own copy" - i.e. there's no chance that this stuff leaks out into
other users of the Schema. I think that's actually quite appropriate
and unlikely to cause unintended consequences.

>
> [Remainder left for later...]
>


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