qapi: Track location that created an implicit type

A future patch will move some error checking from the parser
to the various QAPISchema*.check() methods, which run only
after parsing completes. It will thus be possible to create
a python instance representing an implicit QAPI type that
parses fine but will fail validation during check(). Since
all errors have to have an associated 'info' location, we
need a location to be associated with those implicit types.
The intuitive info to use is the location of the enclosing
entity that caused the creation of the implicit type.

Note that we do not anticipate builtin types being used in
an error message (as they are not part of the user's QAPI
input, the user can't cause a semantic error in their
behavior), so we exempt those types from requiring info, by
setting a flag to track the completion of _def_predefineds(),
and tracking that flag in _def_entity().

No change to the generated code.

Backports commit 99df5289d8c7ebf373c3570d8fba3f3a73360281 from qemu

qemu/scripts/qapi.py

@@ -790,6 +790,11 @@ class QAPISchemaEntity(object):
     def __init__(self, name, info):
         assert isinstance(name, str)
         self.name = name
+        # For explicitly defined entities, info points to the (explicit)
+        # definition.  For builtins (and their arrays), info is None.
+        # For implicitly defined entities, info points to a place that
+        # triggered the implicit definition (there may be more than one
+        # such place).
         self.info = info
 
     def c_name(self):
@@ -903,6 +908,10 @@ class QAPISchemaEnumType(QAPISchemaType):
     def check(self, schema):
         assert len(set(self.values)) == len(self.values)
 
+    def is_implicit(self):
+        # See QAPISchema._make_implicit_enum_type()
+        return self.name[-4:] == 'Kind'
+
     def c_type(self, is_param=False):
         return c_name(self.name)
 
@@ -929,6 +938,9 @@ class QAPISchemaArrayType(QAPISchemaType):
         self.element_type = schema.lookup_type(self._element_type_name)
         assert self.element_type
 
+    def is_implicit(self):
+        return True
+
     def json_type(self):
         return 'array'
 
@@ -973,6 +985,10 @@ class QAPISchemaObjectType(QAPISchemaType):
             self.variants.check(schema, members, seen)
         self.members = members
 
+    def is_implicit(self):
+        # See QAPISchema._make_implicit_object_type()
+        return self.name[0] == ':'
+
     def c_name(self):
         assert not self.is_implicit()
         return QAPISchemaType.c_name(self)
@@ -1119,7 +1135,9 @@ class QAPISchema(object):
         try:
             self.exprs = check_exprs(QAPISchemaParser(open(fname, "r")).exprs)
             self._entity_dict = {}
+            self._predefining = True
             self._def_predefineds()
+            self._predefining = False
             self._def_exprs()
             self.check()
         except (QAPISchemaError, QAPIExprError), err:
@@ -1127,6 +1145,8 @@ class QAPISchema(object):
             exit(1)
 
     def _def_entity(self, ent):
+        # Only the predefined types are allowed to not have info
+        assert ent.info or self._predefining
         assert ent.name not in self._entity_dict
         self._entity_dict[ent.name] = ent
 
@@ -1147,7 +1167,7 @@ class QAPISchema(object):
         # declared in the first file whether or not they are used.  Nicer
         # would be to use lazy instantiation, while figuring out how to
         # avoid compilation issues with multiple qapi-types.h.
-        self._make_array_type(name)
+        self._make_array_type(name, None)
 
     def _def_predefineds(self):
         for t in [('str',    'string',  'char' + pointer_suffix, 'NULL'),
@@ -1169,25 +1189,25 @@ class QAPISchema(object):
                                                           [], None)
         self._def_entity(self.the_empty_object_type)
 
-    def _make_implicit_enum_type(self, name, values):
+    def _make_implicit_enum_type(self, name, info, values):
         name = name + 'Kind'   # Use namespace reserved by add_name()
-        self._def_entity(QAPISchemaEnumType(name, None, values, None))
+        self._def_entity(QAPISchemaEnumType(name, info, values, None))
         return name
 
-    def _make_array_type(self, element_type):
+    def _make_array_type(self, element_type, info):
         # TODO fooList namespace is not reserved; user can create collisions,
         # or abuse our type system with ['fooList'] for 2D array
         name = element_type + 'List'
         if not self.lookup_type(name):
-            self._def_entity(QAPISchemaArrayType(name, None, element_type))
+            self._def_entity(QAPISchemaArrayType(name, info, element_type))
         return name
 
-    def _make_implicit_object_type(self, name, role, members):
+    def _make_implicit_object_type(self, name, info, role, members):
         if not members:
             return None
         name = ':obj-%s-%s' % (name, role)
         if not self.lookup_entity(name, QAPISchemaObjectType):
-            self._def_entity(QAPISchemaObjectType(name, None, None,
+            self._def_entity(QAPISchemaObjectType(name, info, None,
                                                   members, None))
         return name
 
@@ -1197,18 +1217,18 @@ class QAPISchema(object):
         prefix = expr.get('prefix')
         self._def_entity(QAPISchemaEnumType(name, info, data, prefix))
 
-    def _make_member(self, name, typ):
+    def _make_member(self, name, typ, info):
         optional = False
         if name.startswith('*'):
             name = name[1:]
             optional = True
         if isinstance(typ, list):
             assert len(typ) == 1
-            typ = self._make_array_type(typ[0])
+            typ = self._make_array_type(typ[0], info)
         return QAPISchemaObjectTypeMember(name, typ, optional)
 
-    def _make_members(self, data):
+    def _make_members(self, data, info):
-        return [self._make_member(key, value)
+        return [self._make_member(key, value, info)
                 for (key, value) in data.iteritems()]
 
     def _def_struct_type(self, expr, info):
@@ -1216,22 +1236,22 @@ class QAPISchema(object):
         base = expr.get('base')
         data = expr['data']
         self._def_entity(QAPISchemaObjectType(name, info, base,
-                                              self._make_members(data),
+                                              self._make_members(data, info),
                                               None))
 
     def _make_variant(self, case, typ):
         return QAPISchemaObjectTypeVariant(case, typ)
 
-    def _make_simple_variant(self, case, typ):
+    def _make_simple_variant(self, case, typ, info):
         if isinstance(typ, list):
             assert len(typ) == 1
-            typ = self._make_array_type(typ[0])
+            typ = self._make_array_type(typ[0], info)
-        typ = self._make_implicit_object_type(typ, 'wrapper',
+        typ = self._make_implicit_object_type(
-                                              [self._make_member('data', typ)])
+            typ, info, 'wrapper', [self._make_member('data', typ, info)])
         return QAPISchemaObjectTypeVariant(case, typ)
 
-    def _make_implicit_tag(self, type_name, variants):
+    def _make_implicit_tag(self, type_name, info, variants):
-        typ = self._make_implicit_enum_type(type_name,
+        typ = self._make_implicit_enum_type(type_name, info,
                                             [v.name for v in variants])
         return QAPISchemaObjectTypeMember('type', typ, False)
 
@@ -1245,12 +1265,12 @@ class QAPISchema(object):
             variants = [self._make_variant(key, value)
                         for (key, value) in data.iteritems()]
         else:
-            variants = [self._make_simple_variant(key, value)
+            variants = [self._make_simple_variant(key, value, info)
                         for (key, value) in data.iteritems()]
-            tag_member = self._make_implicit_tag(name, variants)
+            tag_member = self._make_implicit_tag(name, info, variants)
         self._def_entity(
             QAPISchemaObjectType(name, info, base,
-                                 self._make_members(OrderedDict()),
+                                 self._make_members(OrderedDict(), info),
                                  QAPISchemaObjectTypeVariants(tag_name,
                                                               tag_member,
                                                               variants)))
@@ -1260,7 +1280,7 @@ class QAPISchema(object):
         data = expr['data']
         variants = [self._make_variant(key, value)
                     for (key, value) in data.iteritems()]
-        tag_member = self._make_implicit_tag(name, variants)
+        tag_member = self._make_implicit_tag(name, info, variants)
         self._def_entity(
             QAPISchemaAlternateType(name, info,
                                     QAPISchemaObjectTypeVariants(None,
@@ -1274,11 +1294,11 @@ class QAPISchema(object):
         gen = expr.get('gen', True)
         success_response = expr.get('success-response', True)
         if isinstance(data, OrderedDict):
-            data = self._make_implicit_object_type(name, 'arg',
+            data = self._make_implicit_object_type(
-                                                   self._make_members(data))
+                name, info, 'arg', self._make_members(data, info))
         if isinstance(rets, list):
             assert len(rets) == 1
-            rets = self._make_array_type(rets[0])
+            rets = self._make_array_type(rets[0], info)
         self._def_entity(QAPISchemaCommand(name, info, data, rets, gen,
                                            success_response))
 
@@ -1286,8 +1306,8 @@ class QAPISchema(object):
         name = expr['event']
         data = expr.get('data')
         if isinstance(data, OrderedDict):
-            data = self._make_implicit_object_type(name, 'arg',
+            data = self._make_implicit_object_type(
-                                                   self._make_members(data))
+                name, info, 'arg', self._make_members(data, info))
         self._def_entity(QAPISchemaEvent(name, info, data))
 
     def _def_exprs(self):