qapi/introspect: Use @dataclass to simplify

A TODO comment in class Annotated reminds us to simplify it once we
can use @dataclass, new in Python 3.7.  We have that now, so do it.

There's a similar comment in scripts/qapi/source.py, but I can't
figure out how to use @dataclass there.  Left for another day.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20250227080757.3978333-4-armbru@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

scripts/qapi/introspect.py

@@ -11,6 +11,7 @@
 See the COPYING file in the top-level directory.
 """
 
+from dataclasses import dataclass
 from typing import (
     Any,
     Dict,
@@ -79,19 +80,16 @@
 _ValueT = TypeVar('_ValueT', bound=_Value)
 
 
+@dataclass
 class Annotated(Generic[_ValueT]):
     """
     Annotated generally contains a SchemaInfo-like type (as a dict),
     But it also used to wrap comments/ifconds around scalar leaf values,
     for the benefit of features and enums.
     """
-    # TODO: Remove after Python 3.7 adds @dataclass:
-    # pylint: disable=too-few-public-methods
-    def __init__(self, value: _ValueT, ifcond: QAPISchemaIfCond,
-                 comment: Optional[str] = None):
-        self.value = value
-        self.comment: Optional[str] = comment
-        self.ifcond = ifcond
+    value: _ValueT
+    ifcond: QAPISchemaIfCond
+    comment: Optional[str] = None
 
 
 def _tree_to_qlit(obj: JSONValue,