sphinx/qapidoc: Fix to generate doc for explicit, unboxed arguments

When a command's arguments are specified as an explicit type T,
generated documentation points to the members of T.

Example:

    ##
    # @announce-self:
    #
    # Trigger generation of broadcast RARP frames to update network
    [...]
    ##
    { 'command': 'announce-self', 'boxed': true,
      'data' : 'AnnounceParameters'}

generates

    "announce-self" (Command)
    -------------------------

    Trigger generation of broadcast RARP frames to update network
    [...]

    Arguments
    ~~~~~~~~~

    The members of "AnnounceParameters"

Except when the command takes its arguments unboxed , i.e. it doesn't
have 'boxed': true, we generate *nothing*.  A few commands have a
reference in their doc comment to compensate, but most don't.

Example:

    ##
    # @blockdev-snapshot-sync:
    #
    # Takes a synchronous snapshot of a block device.
    #
    # For the arguments, see the documentation of BlockdevSnapshotSync.
    [...]
    ##
    { 'command': 'blockdev-snapshot-sync',
      'data': 'BlockdevSnapshotSync',
      'allow-preconfig': true }

generates

    "blockdev-snapshot-sync" (Command)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    Takes a synchronous snapshot of a block device.

    For the arguments, see the documentation of BlockdevSnapshotSync.
    [...]

Same for event data.

Fix qapidoc.py to generate the reference regardless of boxing.  Delete
now redundant references in the doc comments.

Fixes: 4078ee5469e5 (docs/sphinx: Add new qapi-doc Sphinx extension)
Cc: qemu-stable@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20240628112756.794237-1-armbru@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>

docs/sphinx/qapidoc.py

@@ -230,15 +230,15 @@ def _nodes_for_enum_values(self, doc):
         section += dlnode
         return [section]
 
-    def _nodes_for_arguments(self, doc, boxed_arg_type):
+    def _nodes_for_arguments(self, doc, arg_type):
         """Return list of doctree nodes for the arguments section"""
-        if boxed_arg_type:
+        if arg_type and not arg_type.is_implicit():
             assert not doc.args
             section = self._make_section('Arguments')
             dlnode = nodes.definition_list()
             dlnode += self._make_dlitem(
                 [nodes.Text('The members of '),
-                 nodes.literal('', boxed_arg_type.name)],
+                 nodes.literal('', arg_type.name)],
                 None)
             section += dlnode
             return [section]
@@ -352,8 +352,7 @@ def visit_command(self, name, info, ifcond, features, arg_type,
                       allow_preconfig, coroutine):
         doc = self._cur_doc
         self._add_doc('Command',
-                      self._nodes_for_arguments(doc,
-                                                arg_type if boxed else None)
+                      self._nodes_for_arguments(doc, arg_type)
                       + self._nodes_for_features(doc)
                       + self._nodes_for_sections(doc)
                       + self._nodes_for_if_section(ifcond))
@@ -361,8 +360,7 @@ def visit_command(self, name, info, ifcond, features, arg_type,
     def visit_event(self, name, info, ifcond, features, arg_type, boxed):
         doc = self._cur_doc
         self._add_doc('Event',
-                      self._nodes_for_arguments(doc,
-                                                arg_type if boxed else None)
+                      self._nodes_for_arguments(doc, arg_type)
                       + self._nodes_for_features(doc)
                       + self._nodes_for_sections(doc)
                       + self._nodes_for_if_section(ifcond))

qapi/block-core.json

@@ -1675,8 +1675,6 @@
 #
 # Takes a synchronous snapshot of a block device.
 #
-# For the arguments, see the documentation of BlockdevSnapshotSync.
-#
 # Errors:
 #     - If @device is not a valid block device, DeviceNotFound
 #
@@ -1705,8 +1703,6 @@
 # device, the block device changes to using 'overlay' as its new
 # active image.
 #
-# For the arguments, see the documentation of BlockdevSnapshot.
-#
 # Features:
 #
 # @allow-write-only-overlay: If present, the check whether this
@@ -6065,9 +6061,6 @@
 # string, or a snapshot with name already exists, the operation will
 # fail.
 #
-# For the arguments, see the documentation of
-# BlockdevSnapshotInternal.
-#
 # Errors:
 #     - If @device is not a valid block device, GenericError
 #     - If any snapshot matching @name exists, or @name is empty,