[Qemu-devel] [PATCH v8 12/18] 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; similar
to what was done for array types in an earlier patch.

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>

---
v8: rebase to earlier changes, improve comment, rework predefined
flag name
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 | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/scripts/qapi.py b/scripts/qapi.py
index 80c026b..c9ce9ee 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -793,9 +793,9 @@ class QAPISchemaEntity(object):
         # For explicitly defined entities, info points to the (explicit)
         # definition.  For builtins (and their arrays), info is None.
         # For other arrays, info points to an explicit place that uses
-        # the array (there may be more than one such place).
-        # TODO For other implicitly defined entities, it should point to
-        # a place that triggers implicit definition.
+        # the array (there may be more than one such place).  For other
+        # implicitly defined entities, it points to the place that
+        # triggered the implicit definition.
         self.info = info

     def c_name(self):
@@ -1146,7 +1146,9 @@ 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:
@@ -1154,6 +1156,8 @@ 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

@@ -1196,9 +1200,9 @@ 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'   # 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, info):
@@ -1209,12 +1213,12 @@ 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

@@ -1254,11 +1258,11 @@ 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)

@@ -1274,7 +1278,7 @@ class QAPISchema(object):
         else:
             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(), info),
@@ -1287,7 +1291,7 @@ 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,
@@ -1302,7 +1306,7 @@ 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)
@@ -1314,7 +1318,7 @@ 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