[PATCH 4/9] qapi: Tools for sets of special feature flags in generated code

[Markus Armbruster]

New enum QapiSpecialFeature enumerates the special feature flags.

New helper gen_special_features() returns code to represent a
collection of special feature flags as a bitset.

The next few commits will put them to use.

Signed-off-by: Markus Armbruster <armbru at redhat.com>
---
 include/qapi/util.h    |  4 ++++
 scripts/qapi/gen.py    | 13 +++++++++++++
 scripts/qapi/schema.py |  3 +++
 3 files changed, 20 insertions(+)

diff --git a/include/qapi/util.h b/include/qapi/util.h
index 257c600f99..7a8d5c7d72 100644
--- a/include/qapi/util.h
+++ b/include/qapi/util.h
@@ -11,6 +11,10 @@
 #ifndef QAPI_UTIL_H
 #define QAPI_UTIL_H
 
+typedef enum {
+    QAPI_DEPRECATED,
+} QapiSpecialFeature;
+
 /* QEnumLookup flags */
 #define QAPI_ENUM_DEPRECATED 1
 
diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index 2ec1e7b3b6..9d07b88cf6 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -29,6 +29,7 @@
     mcgen,
 )
 from .schema import (
+    QAPISchemaFeature,
     QAPISchemaIfCond,
     QAPISchemaModule,
     QAPISchemaObjectType,
@@ -37,6 +38,18 @@
 from .source import QAPISourceInfo
 
 
+def gen_special_features(features: QAPISchemaFeature):
+    ret = ''
+    sep = ''
+
+    for feat in features:
+        if feat.is_special():
+            ret += ('%s1u << QAPI_%s' % (sep, feat.name.upper()))
+            sep = ' | '
+
+    return ret or '0'
+
+
 class QAPIGen:
     def __init__(self, fname: str):
         self.fname = fname
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index 6d5f46509a..55f82d7389 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -725,6 +725,9 @@ def connect_doc(self, doc):
 class QAPISchemaFeature(QAPISchemaMember):
     role = 'feature'
 
+    def is_special(self):
+        return self.name in ('deprecated')
+
 
 class QAPISchemaObjectTypeMember(QAPISchemaMember):
     def __init__(self, name, info, typ, optional, ifcond=None, features=None):
-- 
2.31.1