qapi: Generalize enum member policy checking

The code to check enumeration value policy can see special feature
flag 'deprecated' in QEnumLookup member flags[value].  I want to make
feature flag 'unstable' visible there as well, so I can add policy for
it.

Instead of extending flags[], replace it by @special_features (a
bitset of QapiSpecialFeature), because that's how special features get
passed around elsewhere.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Message-Id: <20211028102520.747396-8-armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>

include/qapi/util.h

@@ -15,12 +15,9 @@ typedef enum {
     QAPI_DEPRECATED,
 } QapiSpecialFeature;
 
-/* QEnumLookup flags */
-#define QAPI_ENUM_DEPRECATED 1
-
 typedef struct QEnumLookup {
     const char *const *array;
-    const unsigned char *const flags;
+    const unsigned char *const special_features;
     const int size;
 } QEnumLookup;
 

qapi/qapi-visit-core.c

@@ -408,7 +408,8 @@ static bool input_type_enum(Visitor *v, const char *name, int *obj,
         return false;
     }
 
-    if (lookup->flags && (lookup->flags[value] & QAPI_ENUM_DEPRECATED)) {
+    if (lookup->special_features
+        && (lookup->special_features[value] & QAPI_DEPRECATED)) {
         switch (v->compat_policy.deprecated_input) {
         case COMPAT_POLICY_INPUT_ACCEPT:
             break;

scripts/qapi/types.py

@@ -16,7 +16,7 @@
 from typing import List, Optional
 
 from .common import c_enum_const, c_name, mcgen
-from .gen import QAPISchemaModularCVisitor, ifcontext
+from .gen import QAPISchemaModularCVisitor, gen_special_features, ifcontext
 from .schema import (
     QAPISchema,
     QAPISchemaEnumMember,
@@ -39,7 +39,7 @@ def gen_enum_lookup(name: str,
                     members: List[QAPISchemaEnumMember],
                     prefix: Optional[str] = None) -> str:
     max_index = c_enum_const(name, '_MAX', prefix)
-    flags = ''
+    feats = ''
     ret = mcgen('''
 
 const QEnumLookup %(c_name)s_lookup = {
@@ -54,19 +54,21 @@ def gen_enum_lookup(name: str,
 ''',
                      index=index, name=memb.name)
         ret += memb.ifcond.gen_endif()
-        if 'deprecated' in (f.name for f in memb.features):
-            flags += mcgen('''
-        [%(index)s] = QAPI_ENUM_DEPRECATED,
+
+        special_features = gen_special_features(memb.features)
+        if special_features != '0':
+            feats += mcgen('''
+        [%(index)s] = %(special_features)s,
 ''',
-                           index=index)
+                           index=index, special_features=special_features)
 
-    if flags:
+    if feats:
         ret += mcgen('''
     },
-    .flags = (const unsigned char[%(max_index)s]) {
+    .special_features = (const unsigned char[%(max_index)s]) {
 ''',
                      max_index=max_index)
-        ret += flags
+        ret += feats
 
     ret += mcgen('''
     },