[PATCH 13/27] docs/qapi-domain: add qapi:enum directive

[John Snow]

Add the .. qapi:enum:: directive, object, and :qapi:enum:`name`
cross-reference role.

Add the :value name: field list for documenting Enum values.

Of note, also introduce a new "type" role that is intended to be used by
other QAPI object directives to cross-reference arbitrary QAPI type
names, but will exclude commands, events, and modules from
consideration.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 docs/qapi/index.rst        | 14 ++++++++++++++
 docs/sphinx/qapi-domain.py | 24 ++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/docs/qapi/index.rst b/docs/qapi/index.rst
index 39fe4dd2dae..cf794e6e739 100644
--- a/docs/qapi/index.rst
+++ b/docs/qapi/index.rst
@@ -113,3 +113,17 @@ Explicit cross-referencing syntax for QAPI modules is 
available with
    At the moment, the order of grouped sections is based on the order in
    which each group was encountered. This example will render Arguments
    first, and then Features; but the order can be any that you choose.
+
+.. qapi:enum:: BitmapSyncMode
+   :since: 4.2
+
+   An enumeration of possible behaviors for the synchronization of a
+   bitmap when used for data copy operations.
+
+   :value on-success: The bitmap is only synced when the operation is
+      successful. This is the behavior always used for
+      ``INCREMENTAL`` backups.
+   :value never: The bitmap is never synchronized with the operation, and
+      is treated solely as a read-only manifest of blocks to copy.
+   :value always: The bitmap is always synchronized with the operation,
+      regardless of whether or not the operation was successful.
diff --git a/docs/sphinx/qapi-domain.py b/docs/sphinx/qapi-domain.py
index 5d44dba6cd3..6759c39290d 100644
--- a/docs/sphinx/qapi-domain.py
+++ b/docs/sphinx/qapi-domain.py
@@ -289,6 +289,22 @@ class QAPICommand(QAPIObject):
     )
 
 
+class QAPIEnum(QAPIObject):
+    """Description of a QAPI Enum."""
+
+    doc_field_types = QAPIObject.doc_field_types.copy()
+    doc_field_types.extend(
+        [
+            GroupedField(
+                "value",
+                label=_("Values"),
+                names=("value",),
+                can_collapse=True,
+            )
+        ]
+    )
+
+
 class QAPIModule(SphinxDirective):
     """
     Directive to mark description of a new module.
@@ -434,9 +450,14 @@ class QAPIDomain(Domain):
     # This table associates cross-reference object types (key) with an
     # ObjType instance, which defines the valid cross-reference roles
     # for each object type.
+    #
+    # e.g., the :qapi:type: cross-reference role can refer to enum,
+    # struct, union, or alternate objects; but :qapi:obj: can refer to
+    # anything. Each object also gets its own targeted cross-reference role.
     object_types: Dict[str, ObjType] = {
         "module": ObjType(_("module"), "mod", "obj"),
         "command": ObjType(_("command"), "cmd", "obj"),
+        "enum": ObjType(_("enum"), "enum", "obj", "type"),
     }
 
     # Each of these provides a ReST directive,
@@ -444,6 +465,7 @@ class QAPIDomain(Domain):
     directives = {
         "module": QAPIModule,
         "command": QAPICommand,
+        "enum": QAPIEnum,
     }
 
     # These are all cross-reference roles; e.g.
@@ -452,6 +474,8 @@ class QAPIDomain(Domain):
     roles = {
         "mod": QAPIXRefRole(),
         "cmd": QAPIXRefRole(),
+        "enum": QAPIXRefRole(),
+        "type": QAPIXRefRole(),  # reference any data type (excludes modules, 
commands, events)
         "obj": QAPIXRefRole(),  # reference *any* type of QAPI object.
     }
 
-- 
2.44.0