[Qemu-devel] [PATCH v7 08/14] qapi: Track location that created an implicit type

[Eric Blake]

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.

Signed-off-by: Eric Blake <address@hidden>

---
v7: better commit message and comments, fix info assertion to
use instance flag rather than ugly leaky abstraction static flag
v6: improve commit message, track implicit enum info, rebase
on new lazy array handling
---
 scripts/qapi.py | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

diff --git a/scripts/qapi.py b/scripts/qapi.py
index f5040da..e49f72b 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -795,9 +795,9 @@ class QAPISchemaEntity(object):
         self.name = name
         # For explicitly defined entities, info points to the (explicit)
         # definition.  For builtins (and their arrays), info is None.
-        # TODO For other implicitly defined entities, it should point to
-        # a place that triggers implicit definition; there may be more
-        # than one such place.
+        # For other implicitly defined entities, it points to a place
+        # that triggers implicit definition; there may be more than one
+        # such place.
         self.info = info

     def c_name(self):
@@ -1153,7 +1153,9 @@ class QAPISchema(object):
         try:
             self.exprs = check_exprs(QAPISchemaParser(open(fname, "r")).exprs)
             self._entity_dict = {}
+            self._predefined_done = False
             self._def_predefineds()
+            self._predefined_done = True
             self._def_exprs()
             self.check()
         except (QAPISchemaError, QAPIExprError), err:
@@ -1161,6 +1163,9 @@ class QAPISchema(object):
             exit(1)

     def _def_entity(self, ent):
+        if self._predefined_done:
+            # Only the predefined types are allowed to not have info
+            assert ent.info
         assert ent.name not in self._entity_dict
         self._entity_dict[ent.name] = ent

@@ -1203,9 +1208,9 @@ 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'
-        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, info):
@@ -1214,12 +1219,12 @@ class QAPISchema(object):
             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

@@ -1259,11 +1264,11 @@ class QAPISchema(object):
             assert len(typ) == 1
             typ = self._make_array_type(typ[0], info)
         typ = self._make_implicit_object_type(
-            typ, 'wrapper', [self._make_member('data', typ, info)])
+            typ, info, 'wrapper', [self._make_member('data', typ, info)])
         return QAPISchemaObjectTypeVariant(case, typ)

-    def _make_implicit_tag(self, type_name, variants):
-        typ = self._make_implicit_enum_type(type_name,
+    def _make_implicit_tag(self, type_name, info, variants):
+        typ = self._make_implicit_enum_type(type_name, info,
                                             [v.name for v in variants])
         return QAPISchemaObjectTypeUnionTag('type', typ, False)

@@ -1279,7 +1284,7 @@ class QAPISchema(object):
         else:
             variants = [self._make_simple_variant(key, value, info)
                         for (key, value) in data.iteritems()]
-            tag_enum = self._make_implicit_tag(name, variants)
+            tag_enum = self._make_implicit_tag(name, info, variants)
         self._def_entity(
             QAPISchemaObjectType(name, info, base,
                                  self._make_members(OrderedDict(), info),
@@ -1292,7 +1297,7 @@ class QAPISchema(object):
         data = expr['data']
         variants = [self._make_variant(key, value)
                     for (key, value) in data.iteritems()]
-        tag_enum = self._make_implicit_tag(name, variants)
+        tag_enum = self._make_implicit_tag(name, info, variants)
         self._def_entity(
             QAPISchemaAlternateType(name, info,
                                     QAPISchemaObjectTypeVariants(None,
@@ -1307,7 +1312,7 @@ class QAPISchema(object):
         success_response = expr.get('success-response', True)
         if isinstance(data, OrderedDict):
             data = self._make_implicit_object_type(
-                name, 'arg', self._make_members(data, info))
+                name, info, 'arg', self._make_members(data, info))
         if isinstance(rets, list):
             assert len(rets) == 1
             rets = self._make_array_type(rets[0], info)
@@ -1319,7 +1324,7 @@ class QAPISchema(object):
         data = expr.get('data')
         if isinstance(data, OrderedDict):
             data = self._make_implicit_object_type(
-                name, 'arg', self._make_members(data, info))
+                name, info, 'arg', self._make_members(data, info))
         self._def_entity(QAPISchemaEvent(name, info, data))

     def _def_exprs(self):
-- 
2.4.3