qapi: Convert QType into QAPI built-in enum type

What's more meta than using qapi to define qapi? :)

Convert QType into a full-fledged[*] builtin qapi enum type, so
that a subsequent patch can then use it as the discriminator
type of qapi alternate types. Fortunately, the judicious use of
'prefix' in the qapi definition avoids churn to the spelling of
the enum constants.

To avoid circular definitions, we have to flip the order of
inclusion between "qobject.h" vs. "qapi-types.h". Back in commit
28770e0, we had the latter include the former, so that we could
use 'QObject *' for our implementation of 'any'. But that usage
also works with only a forward declaration, whereas the
definition of QObject requires QType to be a complete type.

[*] The type has to be builtin, rather than declared in
qapi/common.json, because we want to use it for alternates even
when common.json is not included. But since it is the first
builtin enum type, we have to add special cases to qapi-types
and qapi-visit to only emit definitions once, even when two
qapi files are being compiled into the same binary (the way we
already handled builtin list types like 'intList'). We may
need to revisit how multiple qapi files share common types,
but that's a project for another day.

Backports commit 7264f5c50cc1be0f1406e3ebb45aedcca02f603a from qemu

msvc/unicorn/qapi-types.c

@@ -18,7 +18,7 @@
 #include "qapi-types.h"
 #include "qapi-visit.h"
 
-const char *const ErrorClass_lookup[] = {
+const char *const QapiErrorClass_lookup[] = {
     "GenericError",
     "CommandNotFound",
     "DeviceEncrypted",
@@ -55,6 +55,18 @@ void qapi_free_DummyForceArrays(DummyForceArrays *obj)
     qapi_dealloc_visitor_cleanup(qdv);
 }
 
+const char *const QType_lookup[] = {
+    "none",
+    "qnull",
+    "qint",
+    "qstring",
+    "qdict",
+    "qlist",
+    "qfloat",
+    "qbool",
+    NULL,
+};
+
 void qapi_free_X86CPUFeatureWordInfo(X86CPUFeatureWordInfo *obj)
 {
     QapiDeallocVisitor *qdv;

msvc/unicorn/qapi-types.h

@@ -16,13 +16,26 @@
 #ifndef QAPI_TYPES_H
 #define QAPI_TYPES_H
 
-#include "qapi/qmp/qobject.h"
+#include "qemu/typedefs.h"
 #include "unicorn/platform.h"
 
 #ifndef QAPI_TYPES_BUILTIN
 #define QAPI_TYPES_BUILTIN
 
 
+typedef enum QType {
+    QTYPE_NONE = 0,
+    QTYPE_QNULL = 1,
+    QTYPE_QINT = 2,
+    QTYPE_QSTRING = 3,
+    QTYPE_QDICT = 4,
+    QTYPE_QLIST = 5,
+    QTYPE_QFLOAT = 6,
+    QTYPE_QBOOL = 7,
+    QTYPE__MAX = 8,
+} QType;
+extern const char *const QType_lookup[];
+
 typedef struct anyList anyList;
 struct anyList {
     union {
@@ -168,16 +181,16 @@ void qapi_free_uint8List(uint8List *obj);
 
 typedef struct DummyForceArrays DummyForceArrays;
 
-typedef enum ErrorClass {
-    ERROR_CLASS_GENERIC_ERROR = 0,
-    ERROR_CLASS_COMMAND_NOT_FOUND = 1,
-    ERROR_CLASS_DEVICE_ENCRYPTED = 2,
-    ERROR_CLASS_DEVICE_NOT_ACTIVE = 3,
-    ERROR_CLASS_DEVICE_NOT_FOUND = 4,
-    ERROR_CLASS_KVM_MISSING_CAP = 5,
-    ERROR_CLASS_MAX = 6,
-} ErrorClass;
-extern const char *const ErrorClass_lookup[];
+typedef enum QapiErrorClass {
+    QAPI_ERROR_CLASS_GENERICERROR = 0,
+    QAPI_ERROR_CLASS_COMMANDNOTFOUND = 1,
+    QAPI_ERROR_CLASS_DEVICEENCRYPTED = 2,
+    QAPI_ERROR_CLASS_DEVICENOTACTIVE = 3,
+    QAPI_ERROR_CLASS_DEVICENOTFOUND = 4,
+    QAPI_ERROR_CLASS_KVMMISSINGCAP = 5,
+    QAPI_ERROR_CLASS__MAX = 6,
+} QapiErrorClass;
+extern const char *const QapiErrorClass_lookup[];
 
 typedef struct X86CPUFeatureWordInfo X86CPUFeatureWordInfo;
 
@@ -192,13 +205,15 @@ typedef enum X86CPURegister32 {
     X86_CPU_REGISTER32_EBP = 5,
     X86_CPU_REGISTER32_ESI = 6,
     X86_CPU_REGISTER32_EDI = 7,
-    X86_CPU_REGISTER32_MAX = 8,
+    X86_CPU_REGISTER32__MAX = 8,
 } X86CPURegister32;
 extern const char *const X86CPURegister32_lookup[];
+
 struct DummyForceArrays {
     X86CPUFeatureWordInfoList *unused;
 };
 void qapi_free_DummyForceArrays(DummyForceArrays *obj);
+
 struct X86CPUFeatureWordInfo {
     int64_t cpuid_input_eax;
     bool has_cpuid_input_ecx;

msvc/unicorn/qapi-visit.c

@@ -44,9 +44,14 @@ void visit_type_DummyForceArrays(Visitor *v, DummyForceArrays **obj, const char
     error_propagate(errp, err);
 }
 
-void visit_type_ErrorClass(Visitor *v, ErrorClass *obj, const char *name, Error **errp)
+void visit_type_QType(Visitor *v, QType *obj, const char *name, Error **errp)
 {
-    visit_type_enum(v, (int *)obj, ErrorClass_lookup, "ErrorClass", name, errp);
+    visit_type_enum(v, (int *)obj, QType_lookup, "QType", name, errp);
+}
+
+void visit_type_QapiErrorClass(Visitor *v, QapiErrorClass *obj, const char *name, Error **errp)
+{
+    visit_type_enum(v, (int *)obj, QapiErrorClass_lookup, "QapiErrorClass", name, errp);
 }
 
 static void visit_type_X86CPUFeatureWordInfo_fields(Visitor *v, X86CPUFeatureWordInfo **obj, Error **errp)

msvc/unicorn/qapi-visit.h

@@ -23,6 +23,7 @@
 #ifndef QAPI_VISIT_BUILTIN
 #define QAPI_VISIT_BUILTIN
 
+void visit_type_QType(Visitor *v, QType *obj, const char *name, Error **errp);
 void visit_type_anyList(Visitor *v, anyList **obj, const char *name, Error **errp);
 void visit_type_boolList(Visitor *v, boolList **obj, const char *name, Error **errp);
 void visit_type_int16List(Visitor *v, int16List **obj, const char *name, Error **errp);
@@ -41,7 +42,7 @@ void visit_type_uint8List(Visitor *v, uint8List **obj, const char *name, Error *
 #endif /* QAPI_VISIT_BUILTIN */
 
 void visit_type_DummyForceArrays(Visitor *v, DummyForceArrays **obj, const char *name, Error **errp);
-void visit_type_ErrorClass(Visitor *v, ErrorClass *obj, const char *name, Error **errp);
+void visit_type_QapiErrorClass(Visitor *v, QapiErrorClass *obj, const char *name, Error **errp);
 void visit_type_X86CPUFeatureWordInfo(Visitor *v, X86CPUFeatureWordInfo **obj, const char *name, Error **errp);
 void visit_type_X86CPUFeatureWordInfoList(Visitor *v, X86CPUFeatureWordInfoList **obj, const char *name, Error **errp);
 void visit_type_X86CPURegister32(Visitor *v, X86CPURegister32 *obj, const char *name, Error **errp);

qemu/include/qapi/qmp/qobject.h

@@ -34,24 +34,12 @@
 
 #include <stddef.h>
 #include <assert.h>
+#include "qapi-types.h"
 
-typedef enum {
-    QTYPE_NONE,
-    QTYPE_QNULL,
-    QTYPE_QINT,
-    QTYPE_QSTRING,
-    QTYPE_QDICT,
-    QTYPE_QLIST,
-    QTYPE_QFLOAT,
-    QTYPE_QBOOL,
-    QTYPE_QERROR,
-    QTYPE_MAX,
-} QType;
-
-typedef struct QObject {
+struct QObject {
     QType type;
     size_t refcnt;
-} QObject;
+};
 
 /* Objects definitions must include this */
 #define QObject_HEAD  \
@@ -71,7 +59,7 @@ typedef struct QObject {
 /* Initialize an object to default values */
 static inline void qobject_init(QObject *obj, QType type)
 {
-    assert(QTYPE_NONE < type && type < QTYPE_MAX);
+    assert(QTYPE_NONE < type && type < QTYPE__MAX);
     obj->refcnt = 1;
     obj->type = type;
 }
@@ -107,7 +95,7 @@ static inline void qobject_decref(QObject *obj)
  */
 static inline QType qobject_type(const QObject *obj)
 {
-    assert(QTYPE_NONE < obj->type && obj->type < QTYPE_MAX);
+    assert(QTYPE_NONE < obj->type && obj->type < QTYPE__MAX);
     return obj->type;
 }
 

qemu/include/qemu/typedefs.h

@@ -66,6 +66,7 @@ typedef struct QEMUSizedBuffer QEMUSizedBuffer;
 typedef struct QEMUTimer QEMUTimer;
 typedef struct QEMUTimerListGroup QEMUTimerListGroup;
 typedef struct QemuConsole QemuConsole;
+typedef struct QObject QObject;
 typedef struct RAMBlock RAMBlock;
 typedef struct Range Range;
 typedef struct SHPCDevice SHPCDevice;

qemu/qobject/qobject.c

@@ -15,7 +15,7 @@
 #include "qapi/qmp/qlist.h"
 #include "qapi/qmp/qstring.h"
 
-static void (*qdestroy[QTYPE_MAX])(QObject *) = {
+static void (*qdestroy[QTYPE__MAX])(QObject *) = {
     NULL,               /* No such object exists */
     NULL,              /* qnull_ is indestructible */
     qint_destroy_obj,
@@ -29,6 +29,6 @@ static void (*qdestroy[QTYPE_MAX])(QObject *) = {
 void qobject_destroy(QObject *obj)
 {
     assert(!obj->refcnt);
-    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE_MAX);
+    assert(QTYPE_QNULL < obj->type && obj->type < QTYPE__MAX);
     qdestroy[obj->type](obj);
 }

qemu/scripts/qapi-types.py

@@ -111,7 +111,7 @@ extern const int %(c_name)s_qtypes[];
 def gen_alternate_qtypes(name, variants):
     ret = mcgen('''
 
-const int %(c_name)s_qtypes[QTYPE_MAX] = {
+const int %(c_name)s_qtypes[QTYPE__MAX] = {
 ''',
                 c_name=c_name(name))
 
@@ -232,8 +232,15 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
         self.defn += gen_type_cleanup(name)
 
     def visit_enum_type(self, name, info, values, prefix):
-        self._fwdecl += gen_enum(name, values, prefix)
-        self._fwdefn += gen_enum_lookup(name, values, prefix)
+        # Special case for our lone builtin enum type
+        # TODO use something cleaner than existence of info
+        if not info:
+            self._btin += gen_enum(name, values, prefix)
+            if do_builtins:
+                self.defn += gen_enum_lookup(name, values, prefix)
+        else:
+            self._fwdecl += gen_enum(name, values, prefix)
+            self._fwdefn += gen_enum_lookup(name, values, prefix)
 
     def visit_array_type(self, name, info, element_type):
         if isinstance(element_type, QAPISchemaBuiltinType):
@@ -314,8 +321,9 @@ fdef.write(mcgen('''
 ''',
                  prefix=prefix))
 
+# To avoid circular headers, use only typedefs.h here, not qobject.h
 fdecl.write(mcgen('''
-#include "qapi/qmp/qobject.h"
+#include "qemu/typedefs.h"
 #include "unicorn/platform.h"
 '''))
 

qemu/scripts/qapi-visit.py

@@ -345,8 +345,16 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):
                     isinstance(entity, QAPISchemaObjectType))
 
     def visit_enum_type(self, name, info, values, prefix):
-        self.decl += gen_visit_decl(name, scalar=True)
-        self.defn += gen_visit_enum(name)
+        # Special case for our lone builtin enum type
+        # TODO use something cleaner than existence of info
+        if not info:
+            self._btin += gen_visit_decl(name, scalar=True)
+            if do_builtins:
+                self.defn += gen_visit_enum(name)
+        else:
+            self.decl += gen_visit_decl(name, scalar=True)
+            self.defn += gen_visit_enum(name)
+
 
     def visit_array_type(self, name, info, element_type):
         decl = gen_visit_decl(name)

qemu/scripts/qapi.py

@@ -34,6 +34,7 @@ builtin_types = {
     'uint64':   'QTYPE_QINT',
     'size':     'QTYPE_QINT',
     'any':      None,           # any QType possible, actually
+    'QType':    'QTYPE_QSTRING',
 }
 
 # Whitelist of commands allowed to return a non-dictionary
@@ -1245,6 +1246,11 @@ class QAPISchema(object):
         self.the_empty_object_type = QAPISchemaObjectType(':empty', None, None,
                                                           [], None)
         self._def_entity(self.the_empty_object_type)
+        self._def_entity(QAPISchemaEnumType('QType', None,
+                                            ['none', 'qnull', 'qint',
+                                             'qstring', 'qdict', 'qlist',
+                                             'qfloat', 'qbool'],
+                                            'QTYPE'))
 
     def _make_implicit_enum_type(self, name, info, values):
         name = name + 'Kind'   # Use namespace reserved by add_name()