[PATCH 16/19] qapi/schema: add type hints

John Snow posted 19 patches 1 year ago
There is a newer version of this series
[PATCH 16/19] qapi/schema: add type hints
Posted by John Snow 1 year ago
This patch only adds type hints, which aren't utilized at runtime and
don't change the behavior of this module in any way.

In a scant few locations, type hints are removed where no longer
necessary due to inference power from typing all of the rest of
creation; and any type hints that no longer need string quotes are
changed.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 scripts/qapi/schema.py | 554 +++++++++++++++++++++++++++++------------
 1 file changed, 389 insertions(+), 165 deletions(-)

diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index ce5b01b3182..5d19b59def0 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -15,10 +15,20 @@
 # TODO catching name collisions in generated code would be nice
 # pylint: disable=too-many-lines
 
+from __future__ import annotations
+
 from collections import OrderedDict
 import os
 import re
-from typing import List, Optional, cast
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    List,
+    Optional,
+    Union,
+    cast,
+)
 
 from .common import (
     POINTER_SUFFIX,
@@ -30,39 +40,50 @@
 )
 from .error import QAPIError, QAPISemError, QAPISourceError
 from .expr import check_exprs
-from .parser import QAPIExpression, QAPISchemaParser
+from .parser import QAPIDoc, QAPIExpression, QAPISchemaParser
+from .source import QAPISourceInfo
 
 
 class QAPISchemaIfCond:
-    def __init__(self, ifcond=None):
+    def __init__(
+        self,
+        ifcond: Optional[Union[str, Dict[str, object]]] = None,
+    ) -> None:
         self.ifcond = ifcond
 
-    def _cgen(self):
+    def _cgen(self) -> str:
         return cgen_ifcond(self.ifcond)
 
-    def gen_if(self):
+    def gen_if(self) -> str:
         return gen_if(self._cgen())
 
-    def gen_endif(self):
+    def gen_endif(self) -> str:
         return gen_endif(self._cgen())
 
-    def docgen(self):
+    def docgen(self) -> str:
         return docgen_ifcond(self.ifcond)
 
-    def is_present(self):
+    def is_present(self) -> bool:
         return bool(self.ifcond)
 
 
 class QAPISchemaEntity:
-    meta: Optional[str] = None
+    meta: str
 
-    def __init__(self, name: str, info, doc, ifcond=None, features=None):
+    def __init__(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        doc: Optional[QAPIDoc],
+        ifcond: Optional[QAPISchemaIfCond] = None,
+        features: Optional[List[QAPISchemaFeature]] = None,
+    ):
         assert name is None or isinstance(name, str)
         for f in features or []:
             assert isinstance(f, QAPISchemaFeature)
             f.set_defined_in(name)
         self.name = name
-        self._module = None
+        self._module: Optional[QAPISchemaModule] = None
         # 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
@@ -74,102 +95,162 @@ def __init__(self, name: str, info, doc, ifcond=None, features=None):
         self.features = features or []
         self._checked = False
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         if self.name is None:
             return "<%s at 0x%x>" % (type(self).__name__, id(self))
         return "<%s:%s at 0x%x>" % (type(self).__name__, self.name, id(self))
 
-    def c_name(self):
+    def c_name(self) -> str:
         return c_name(self.name)
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         # pylint: disable=unused-argument
         assert not self._checked
-        seen = {}
+        seen: Dict[str, QAPISchemaMember] = {}
         for f in self.features:
             f.check_clash(self.info, seen)
         self._checked = True
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         doc = doc or self.doc
         if doc:
             for f in self.features:
                 doc.connect_feature(f)
 
-    def check_doc(self):
+    def check_doc(self) -> None:
         if self.doc:
             self.doc.check()
 
-    def _set_module(self, schema, info):
+    def _set_module(
+        self, schema: QAPISchema, info: Optional[QAPISourceInfo]
+    ) -> None:
         assert self._checked
         fname = info.fname if info else QAPISchemaModule.BUILTIN_MODULE_NAME
         self._module = schema.module_by_fname(fname)
         self._module.add_entity(self)
 
-    def set_module(self, schema):
+    def set_module(self, schema: QAPISchema) -> None:
         self._set_module(schema, self.info)
 
     @property
-    def ifcond(self):
+    def ifcond(self) -> QAPISchemaIfCond:
         assert self._checked
         return self._ifcond
 
-    def is_implicit(self):
+    def is_implicit(self) -> bool:
         return not self.info
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         # pylint: disable=unused-argument
         assert self._checked
 
-    def describe(self):
+    def describe(self) -> str:
         assert self.meta
         return "%s '%s'" % (self.meta, self.name)
 
 
 class QAPISchemaVisitor:
-    def visit_begin(self, schema):
+    def visit_begin(self, schema: QAPISchema) -> None:
         pass
 
-    def visit_end(self):
+    def visit_end(self) -> None:
         pass
 
-    def visit_module(self, name):
+    def visit_module(self, name: str) -> None:
         pass
 
-    def visit_needed(self, entity):
+    def visit_needed(self, entity: QAPISchemaEntity) -> bool:
         # pylint: disable=unused-argument
         # Default to visiting everything
         return True
 
-    def visit_include(self, name, info):
+    def visit_include(self, name: str, info: Optional[QAPISourceInfo]) -> None:
         pass
 
-    def visit_builtin_type(self, name, info, json_type):
+    def visit_builtin_type(
+        self, name: str, info: Optional[QAPISourceInfo], json_type: str
+    ) -> None:
         pass
 
-    def visit_enum_type(self, name, info, ifcond, features, members, prefix):
+    def visit_enum_type(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        members: List[QAPISchemaEnumMember],
+        prefix: Optional[str],
+    ) -> None:
         pass
 
-    def visit_array_type(self, name, info, ifcond, element_type):
+    def visit_array_type(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        element_type: QAPISchemaType,
+    ) -> None:
         pass
 
-    def visit_object_type(self, name, info, ifcond, features,
-                          base, members, variants):
+    def visit_object_type(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        base: Optional[QAPISchemaObjectType],
+        members: List[QAPISchemaObjectTypeMember],
+        variants: Optional[QAPISchemaVariants],
+    ) -> None:
         pass
 
-    def visit_object_type_flat(self, name, info, ifcond, features,
-                               members, variants):
+    def visit_object_type_flat(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        members: List[QAPISchemaObjectTypeMember],
+        variants: Optional[QAPISchemaVariants],
+    ) -> None:
         pass
 
-    def visit_alternate_type(self, name, info, ifcond, features, variants):
+    def visit_alternate_type(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        variants: QAPISchemaVariants,
+    ) -> None:
         pass
 
-    def visit_command(self, name, info, ifcond, features,
-                      arg_type, ret_type, gen, success_response, boxed,
-                      allow_oob, allow_preconfig, coroutine):
+    def visit_command(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        arg_type: Optional[QAPISchemaObjectType],
+        ret_type: Optional[QAPISchemaType],
+        gen: bool,
+        success_response: bool,
+        boxed: bool,
+        allow_oob: bool,
+        allow_preconfig: bool,
+        coroutine: bool,
+    ) -> None:
         pass
 
-    def visit_event(self, name, info, ifcond, features, arg_type, boxed):
+    def visit_event(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        arg_type: Optional[QAPISchemaObjectType],
+        boxed: bool,
+    ) -> None:
         pass
 
 
@@ -177,9 +258,9 @@ class QAPISchemaModule:
 
     BUILTIN_MODULE_NAME = './builtin'
 
-    def __init__(self, name):
+    def __init__(self, name: str):
         self.name = name
-        self._entity_list = []
+        self._entity_list: List[QAPISchemaEntity] = []
 
     @staticmethod
     def is_system_module(name: str) -> bool:
@@ -208,10 +289,10 @@ def is_builtin_module(cls, name: str) -> bool:
         """
         return name == cls.BUILTIN_MODULE_NAME
 
-    def add_entity(self, ent):
+    def add_entity(self, ent: QAPISchemaEntity) -> None:
         self._entity_list.append(ent)
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         visitor.visit_module(self.name)
         for entity in self._entity_list:
             if visitor.visit_needed(entity):
@@ -219,13 +300,13 @@ def visit(self, visitor):
 
 
 class QAPISchemaInclude(QAPISchemaEntity):
-    def __init__(self, sub_module, info):
+    def __init__(self, sub_module: QAPISchemaModule, info: QAPISourceInfo):
         # Includes are internal entity objects; and may occur multiple times
         name = f"q_include_{info.fname}:{info.line}"
         super().__init__(name, info, None)
         self._sub_module = sub_module
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_include(self._sub_module.name, self.info)
 
@@ -237,17 +318,17 @@ def c_type(self) -> str:
         raise NotImplementedError()
 
     # Return the C type to be used in a parameter list.
-    def c_param_type(self):
+    def c_param_type(self) -> str:
         return self.c_type()
 
     # Return the C type to be used where we suppress boxing.
-    def c_unboxed_type(self):
+    def c_unboxed_type(self) -> str:
         return self.c_type()
 
     def json_type(self) -> str:
         raise NotImplementedError()
 
-    def alternate_qtype(self):
+    def alternate_qtype(self) -> Optional[str]:
         json2qtype = {
             'null':    'QTYPE_QNULL',
             'string':  'QTYPE_QSTRING',
@@ -259,17 +340,17 @@ def alternate_qtype(self):
         }
         return json2qtype.get(self.json_type())
 
-    def doc_type(self):
+    def doc_type(self) -> Optional[str]:
         if self.is_implicit():
             return None
         return self.name
 
-    def need_has_if_optional(self):
+    def need_has_if_optional(self) -> bool:
         # When FOO is a pointer, has_FOO == !!FOO, i.e. has_FOO is redundant.
         # Except for arrays; see QAPISchemaArrayType.need_has_if_optional().
         return not self.c_type().endswith(POINTER_SUFFIX)
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         super().check(schema)
         for feat in self.features:
             if feat.is_special():
@@ -277,7 +358,7 @@ def check(self, schema):
                     self.info,
                     f"feature '{feat.name}' is not supported for types")
 
-    def describe(self):
+    def describe(self) -> str:
         assert self.meta
         return "%s type '%s'" % (self.meta, self.name)
 
@@ -285,7 +366,7 @@ def describe(self):
 class QAPISchemaBuiltinType(QAPISchemaType):
     meta = 'built-in'
 
-    def __init__(self, name, json_type, c_type):
+    def __init__(self, name: str, json_type: str, c_type: str):
         super().__init__(name, None, None)
         assert not c_type or isinstance(c_type, str)
         assert json_type in ('string', 'number', 'int', 'boolean', 'null',
@@ -293,24 +374,24 @@ def __init__(self, name, json_type, c_type):
         self._json_type_name = json_type
         self._c_type_name = c_type
 
-    def c_name(self):
+    def c_name(self) -> str:
         return self.name
 
-    def c_type(self):
+    def c_type(self) -> str:
         return self._c_type_name
 
-    def c_param_type(self):
+    def c_param_type(self) -> str:
         if self.name == 'str':
             return 'const ' + self._c_type_name
         return self._c_type_name
 
-    def json_type(self):
+    def json_type(self) -> str:
         return self._json_type_name
 
-    def doc_type(self):
+    def doc_type(self) -> str:
         return self.json_type()
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_builtin_type(self.name, self.info, self.json_type())
 
@@ -318,7 +399,16 @@ def visit(self, visitor):
 class QAPISchemaEnumType(QAPISchemaType):
     meta = 'enum'
 
-    def __init__(self, name, info, doc, ifcond, features, members, prefix):
+    def __init__(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        doc: Optional[QAPIDoc],
+        ifcond: Optional[QAPISchemaIfCond],
+        features: Optional[List[QAPISchemaFeature]],
+        members: List[QAPISchemaEnumMember],
+        prefix: Optional[str],
+    ):
         super().__init__(name, info, doc, ifcond, features)
         for m in members:
             assert isinstance(m, QAPISchemaEnumMember)
@@ -327,32 +417,32 @@ def __init__(self, name, info, doc, ifcond, features, members, prefix):
         self.members = members
         self.prefix = prefix
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         super().check(schema)
-        seen = {}
+        seen: Dict[str, QAPISchemaMember] = {}
         for m in self.members:
             m.check_clash(self.info, seen)
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         super().connect_doc(doc)
         doc = doc or self.doc
         for m in self.members:
             m.connect_doc(doc)
 
-    def is_implicit(self):
+    def is_implicit(self) -> bool:
         # See QAPISchema._def_predefineds()
         return self.name == 'QType'
 
-    def c_type(self):
+    def c_type(self) -> str:
         return c_name(self.name)
 
-    def member_names(self):
+    def member_names(self) -> List[str]:
         return [m.name for m in self.members]
 
-    def json_type(self):
+    def json_type(self) -> str:
         return 'string'
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_enum_type(
             self.name, self.info, self.ifcond, self.features,
@@ -362,7 +452,9 @@ def visit(self, visitor):
 class QAPISchemaArrayType(QAPISchemaType):
     meta = 'array'
 
-    def __init__(self, name, info, element_type):
+    def __init__(
+        self, name: str, info: Optional[QAPISourceInfo], element_type: str
+    ):
         super().__init__(name, info, None)
         assert isinstance(element_type, str)
         self._element_type_name = element_type
@@ -377,12 +469,12 @@ def element_type(self) -> QAPISchemaType:
             )
         return self._element_type
 
-    def need_has_if_optional(self):
+    def need_has_if_optional(self) -> bool:
         # When FOO is an array, we still need has_FOO to distinguish
         # absent (!has_FOO) from present and empty (has_FOO && !FOO).
         return True
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         super().check(schema)
 
         if self.info:
@@ -396,42 +488,51 @@ def check(self, schema):
         )
         assert not isinstance(self.element_type, QAPISchemaArrayType)
 
-    def set_module(self, schema):
+    def set_module(self, schema: QAPISchema) -> None:
         self._set_module(schema, self.element_type.info)
 
     @property
-    def ifcond(self):
+    def ifcond(self) -> QAPISchemaIfCond:
         assert self._checked
         return self.element_type.ifcond
 
-    def is_implicit(self):
+    def is_implicit(self) -> bool:
         return True
 
-    def c_type(self):
+    def c_type(self) -> str:
         return c_name(self.name) + POINTER_SUFFIX
 
-    def json_type(self):
+    def json_type(self) -> str:
         return 'array'
 
-    def doc_type(self):
+    def doc_type(self) -> Optional[str]:
         elt_doc_type = self.element_type.doc_type()
         if not elt_doc_type:
             return None
         return 'array of ' + elt_doc_type
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_array_type(self.name, self.info, self.ifcond,
                                  self.element_type)
 
-    def describe(self):
+    def describe(self) -> str:
         assert self.meta
         return "%s type ['%s']" % (self.meta, self._element_type_name)
 
 
 class QAPISchemaObjectType(QAPISchemaType):
-    def __init__(self, name, info, doc, ifcond, features,
-                 base, local_members, variants):
+    def __init__(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        doc: Optional[QAPIDoc],
+        ifcond: Optional[QAPISchemaIfCond],
+        features: Optional[List[QAPISchemaFeature]],
+        base: Optional[str],
+        local_members: List[QAPISchemaObjectTypeMember],
+        variants: Optional[QAPISchemaVariants],
+    ):
         # struct has local_members, optional base, and no variants
         # union has base, variants, and no local_members
         super().__init__(name, info, doc, ifcond, features)
@@ -450,7 +551,7 @@ def __init__(self, name, info, doc, ifcond, features,
         self.members: List[QAPISchemaObjectTypeMember] = []
         self._checking = False
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         # This calls another type T's .check() exactly when the C
         # struct emitted by gen_object() contains that T's C struct
         # (pointers don't count).
@@ -496,14 +597,18 @@ def check(self, schema):
     # Check that the members of this type do not cause duplicate JSON members,
     # and update seen to track the members seen so far. Report any errors
     # on behalf of info, which is not necessarily self.info
-    def check_clash(self, info, seen):
+    def check_clash(
+        self,
+        info: Optional[QAPISourceInfo],
+        seen: Dict[str, QAPISchemaMember],
+    ) -> None:
         assert self._checked
         for m in self.members:
             m.check_clash(info, seen)
         if self.variants:
             self.variants.check_clash(info, seen)
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         super().connect_doc(doc)
         doc = doc or self.doc
         if self.base and self.base.is_implicit():
@@ -511,34 +616,34 @@ def connect_doc(self, doc=None):
         for m in self.local_members:
             m.connect_doc(doc)
 
-    def is_implicit(self):
+    def is_implicit(self) -> bool:
         # See QAPISchema._make_implicit_object_type(), as well as
         # _def_predefineds()
         return self.name.startswith('q_')
 
-    def is_empty(self):
+    def is_empty(self) -> bool:
         assert self.members is not None
         return not self.members and not self.variants
 
-    def has_conditional_members(self):
+    def has_conditional_members(self) -> bool:
         assert self.members is not None
         return any(m.ifcond.is_present() for m in self.members)
 
-    def c_name(self):
+    def c_name(self) -> str:
         assert self.name != 'q_empty'
         return super().c_name()
 
-    def c_type(self):
+    def c_type(self) -> str:
         assert not self.is_implicit()
         return c_name(self.name) + POINTER_SUFFIX
 
-    def c_unboxed_type(self):
+    def c_unboxed_type(self) -> str:
         return c_name(self.name)
 
-    def json_type(self):
+    def json_type(self) -> str:
         return 'object'
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_object_type(
             self.name, self.info, self.ifcond, self.features,
@@ -551,7 +656,15 @@ def visit(self, visitor):
 class QAPISchemaAlternateType(QAPISchemaType):
     meta = 'alternate'
 
-    def __init__(self, name, info, doc, ifcond, features, variants):
+    def __init__(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        doc: Optional[QAPIDoc],
+        ifcond: Optional[QAPISchemaIfCond],
+        features: List[QAPISchemaFeature],
+        variants: QAPISchemaVariants,
+    ):
         super().__init__(name, info, doc, ifcond, features)
         assert isinstance(variants, QAPISchemaVariants)
         assert variants.tag_member
@@ -559,7 +672,7 @@ def __init__(self, name, info, doc, ifcond, features, variants):
         variants.tag_member.set_defined_in(self.name)
         self.variants = variants
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         super().check(schema)
         self.variants.tag_member.check(schema)
         # Not calling self.variants.check_clash(), because there's nothing
@@ -567,8 +680,8 @@ def check(self, schema):
         self.variants.check(schema, {})
         # Alternate branch names have no relation to the tag enum values;
         # so we have to check for potential name collisions ourselves.
-        seen = {}
-        types_seen = {}
+        seen: Dict[str, QAPISchemaMember] = {}
+        types_seen: Dict[str, str] = {}
         for v in self.variants.variants:
             v.check_clash(self.info, seen)
             qtype = v.type.alternate_qtype()
@@ -597,26 +710,32 @@ def check(self, schema):
                         % (v.describe(self.info), types_seen[qt]))
                 types_seen[qt] = v.name
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         super().connect_doc(doc)
         doc = doc or self.doc
         for v in self.variants.variants:
             v.connect_doc(doc)
 
-    def c_type(self):
+    def c_type(self) -> str:
         return c_name(self.name) + POINTER_SUFFIX
 
-    def json_type(self):
+    def json_type(self) -> str:
         return 'value'
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_alternate_type(
             self.name, self.info, self.ifcond, self.features, self.variants)
 
 
 class QAPISchemaVariants:
-    def __init__(self, tag_name, info, tag_member, variants):
+    def __init__(
+        self,
+        tag_name: Optional[str],
+        info: QAPISourceInfo,
+        tag_member: Optional[QAPISchemaObjectTypeMember],
+        variants: List[QAPISchemaVariant],
+    ):
         # Unions pass tag_name but not tag_member.
         # Alternates pass tag_member but not tag_name.
         # After check(), tag_member is always set.
@@ -627,11 +746,11 @@ def __init__(self, tag_name, info, tag_member, variants):
             assert isinstance(v, QAPISchemaVariant)
         self._tag_name = tag_name
         self.info = info
-        self._tag_member: Optional[QAPISchemaObjectTypeMember] = tag_member
+        self._tag_member = tag_member
         self.variants = variants
 
     @property
-    def tag_member(self) -> 'QAPISchemaObjectTypeMember':
+    def tag_member(self) -> QAPISchemaObjectTypeMember:
         if self._tag_member is None:
             raise RuntimeError(
                 "QAPISchemaVariants has no tag_member property until "
@@ -639,11 +758,13 @@ def tag_member(self) -> 'QAPISchemaObjectTypeMember':
             )
         return self._tag_member
 
-    def set_defined_in(self, name):
+    def set_defined_in(self, name: str) -> None:
         for v in self.variants:
             v.set_defined_in(name)
 
-    def check(self, schema, seen):
+    def check(
+        self, schema: QAPISchema, seen: Dict[str, QAPISchemaMember]
+    ) -> None:
         if self._tag_name:      # union
             # We need to narrow the member type:
             tmp = seen.get(c_name(self._tag_name))
@@ -713,7 +834,11 @@ def check(self, schema, seen):
                         % (v.describe(self.info), v.type.describe()))
                 v.type.check(schema)
 
-    def check_clash(self, info, seen):
+    def check_clash(
+        self,
+        info: Optional[QAPISourceInfo],
+        seen: Dict[str, QAPISchemaMember],
+    ) -> None:
         for v in self.variants:
             # Reset seen map for each variant, since qapi names from one
             # branch do not affect another branch
@@ -725,18 +850,27 @@ class QAPISchemaMember:
     """ Represents object members, enum members and features """
     role = 'member'
 
-    def __init__(self, name, info, ifcond=None):
+    def __init__(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: Optional[QAPISchemaIfCond] = None,
+    ):
         assert isinstance(name, str)
         self.name = name
         self.info = info
         self.ifcond = ifcond or QAPISchemaIfCond()
-        self.defined_in = None
+        self.defined_in: Optional[str] = None
 
-    def set_defined_in(self, name):
+    def set_defined_in(self, name: str) -> None:
         assert not self.defined_in
         self.defined_in = name
 
-    def check_clash(self, info, seen):
+    def check_clash(
+        self,
+        info: Optional[QAPISourceInfo],
+        seen: Dict[str, QAPISchemaMember],
+    ) -> None:
         cname = c_name(self.name)
         if cname in seen:
             raise QAPISemError(
@@ -745,11 +879,11 @@ def check_clash(self, info, seen):
                 % (self.describe(info), seen[cname].describe(info)))
         seen[cname] = self
 
-    def connect_doc(self, doc):
+    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
         if doc:
             doc.connect_member(self)
 
-    def describe(self, info):
+    def describe(self, info: Optional[QAPISourceInfo]) -> str:
         role = self.role
         meta = 'type'
         defined_in = self.defined_in
@@ -781,14 +915,20 @@ def describe(self, info):
 class QAPISchemaEnumMember(QAPISchemaMember):
     role = 'value'
 
-    def __init__(self, name, info, ifcond=None, features=None):
+    def __init__(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        ifcond: Optional[QAPISchemaIfCond] = None,
+        features: Optional[List[QAPISchemaFeature]] = None,
+    ):
         super().__init__(name, info, ifcond)
         for f in features or []:
             assert isinstance(f, QAPISchemaFeature)
             f.set_defined_in(name)
         self.features = features or []
 
-    def connect_doc(self, doc):
+    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
         super().connect_doc(doc)
         if doc:
             for f in self.features:
@@ -798,12 +938,20 @@ def connect_doc(self, doc):
 class QAPISchemaFeature(QAPISchemaMember):
     role = 'feature'
 
-    def is_special(self):
+    def is_special(self) -> bool:
         return self.name in ('deprecated', 'unstable')
 
 
 class QAPISchemaObjectTypeMember(QAPISchemaMember):
-    def __init__(self, name, info, typ, optional, ifcond=None, features=None):
+    def __init__(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        typ: str,
+        optional: bool,
+        ifcond: Optional[QAPISchemaIfCond] = None,
+        features: Optional[List[QAPISchemaFeature]] = None,
+    ):
         super().__init__(name, info, ifcond)
         assert isinstance(typ, str)
         assert isinstance(optional, bool)
@@ -815,19 +963,19 @@ def __init__(self, name, info, typ, optional, ifcond=None, features=None):
         self.optional = optional
         self.features = features or []
 
-    def need_has(self):
+    def need_has(self) -> bool:
         assert self.type
         return self.optional and self.type.need_has_if_optional()
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         assert self.defined_in
         self.type = schema.resolve_type(self._type_name, self.info,
                                         self.describe)
-        seen = {}
+        seen: Dict[str, QAPISchemaMember] = {}
         for f in self.features:
             f.check_clash(self.info, seen)
 
-    def connect_doc(self, doc):
+    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
         super().connect_doc(doc)
         if doc:
             for f in self.features:
@@ -837,24 +985,42 @@ def connect_doc(self, doc):
 class QAPISchemaVariant(QAPISchemaObjectTypeMember):
     role = 'branch'
 
-    def __init__(self, name, info, typ, ifcond=None):
+    def __init__(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        typ: str,
+        ifcond: QAPISchemaIfCond,
+    ):
         super().__init__(name, info, typ, False, ifcond)
 
 
 class QAPISchemaCommand(QAPISchemaEntity):
     meta = 'command'
 
-    def __init__(self, name, info, doc, ifcond, features,
-                 arg_type, ret_type,
-                 gen, success_response, boxed, allow_oob, allow_preconfig,
-                 coroutine):
+    def __init__(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        doc: Optional[QAPIDoc],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        arg_type: Optional[str],
+        ret_type: Optional[str],
+        gen: bool,
+        success_response: bool,
+        boxed: bool,
+        allow_oob: bool,
+        allow_preconfig: bool,
+        coroutine: bool,
+    ):
         super().__init__(name, info, doc, ifcond, features)
         assert not arg_type or isinstance(arg_type, str)
         assert not ret_type or isinstance(ret_type, str)
         self._arg_type_name = arg_type
-        self.arg_type = None
+        self.arg_type: Optional[QAPISchemaObjectType] = None
         self._ret_type_name = ret_type
-        self.ret_type = None
+        self.ret_type: Optional[QAPISchemaType] = None
         self.gen = gen
         self.success_response = success_response
         self.boxed = boxed
@@ -862,7 +1028,7 @@ def __init__(self, name, info, doc, ifcond, features,
         self.allow_preconfig = allow_preconfig
         self.coroutine = coroutine
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         assert self.info is not None
         super().check(schema)
         if self._arg_type_name:
@@ -897,14 +1063,14 @@ def check(self, schema):
                         "command's 'returns' cannot take %s"
                         % self.ret_type.describe())
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         super().connect_doc(doc)
         doc = doc or self.doc
         if doc:
             if self.arg_type and self.arg_type.is_implicit():
                 self.arg_type.connect_doc(doc)
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_command(
             self.name, self.info, self.ifcond, self.features,
@@ -916,14 +1082,23 @@ def visit(self, visitor):
 class QAPISchemaEvent(QAPISchemaEntity):
     meta = 'event'
 
-    def __init__(self, name, info, doc, ifcond, features, arg_type, boxed):
+    def __init__(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        doc: Optional[QAPIDoc],
+        ifcond: QAPISchemaIfCond,
+        features: List[QAPISchemaFeature],
+        arg_type: Optional[str],
+        boxed: bool,
+    ):
         super().__init__(name, info, doc, ifcond, features)
         assert not arg_type or isinstance(arg_type, str)
         self._arg_type_name = arg_type
-        self.arg_type = None
+        self.arg_type: Optional[QAPISchemaObjectType] = None
         self.boxed = boxed
 
-    def check(self, schema):
+    def check(self, schema: QAPISchema) -> None:
         super().check(schema)
         if self._arg_type_name:
             typ = schema.resolve_type(
@@ -945,14 +1120,14 @@ def check(self, schema):
                     self.info,
                     "conditional event arguments require 'boxed': true")
 
-    def connect_doc(self, doc=None):
+    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
         super().connect_doc(doc)
         doc = doc or self.doc
         if doc:
             if self.arg_type and self.arg_type.is_implicit():
                 self.arg_type.connect_doc(doc)
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         super().visit(visitor)
         visitor.visit_event(
             self.name, self.info, self.ifcond, self.features,
@@ -960,7 +1135,7 @@ def visit(self, visitor):
 
 
 class QAPISchema:
-    def __init__(self, fname):
+    def __init__(self, fname: str):
         self.fname = fname
 
         try:
@@ -972,9 +1147,9 @@ def __init__(self, fname):
 
         exprs = check_exprs(parser.exprs)
         self.docs = parser.docs
-        self._entity_list = []
-        self._entity_dict = {}
-        self._module_dict = OrderedDict()
+        self._entity_list: List[QAPISchemaEntity] = []
+        self._entity_dict: Dict[str, QAPISchemaEntity] = {}
+        self._module_dict: Dict[str, QAPISchemaModule] = OrderedDict()
         self._schema_dir = os.path.dirname(fname)
         self._make_module(QAPISchemaModule.BUILTIN_MODULE_NAME)
         self._make_module(fname)
@@ -984,7 +1159,7 @@ def __init__(self, fname):
         self._def_exprs(exprs)
         self.check()
 
-    def _def_entity(self, ent):
+    def _def_entity(self, ent: QAPISchemaEntity) -> None:
         # Only the predefined types are allowed to not have info
         assert ent.info or self._predefining
         self._entity_list.append(ent)
@@ -1003,7 +1178,11 @@ def _def_entity(self, ent):
                 ent.info, "%s is already defined" % other_ent.describe())
         self._entity_dict[ent.name] = ent
 
-    def lookup_entity(self, name, typ=None):
+    def lookup_entity(
+        self,
+        name: str,
+        typ: Optional[type] = None,
+    ) -> Optional[QAPISchemaEntity]:
         ent = self._entity_dict.get(name)
         if typ and not isinstance(ent, typ):
             return None
@@ -1016,7 +1195,12 @@ def lookup_type(self, name: str) -> Optional[QAPISchemaType]:
         assert isinstance(typ, QAPISchemaType)
         return typ
 
-    def resolve_type(self, name, info, what):
+    def resolve_type(
+        self,
+        name: str,
+        info: Optional[QAPISourceInfo],
+        what: Union[str, Callable[[Optional[QAPISourceInfo]], str]],
+    ) -> QAPISchemaType:
         typ = self.lookup_type(name)
         if not typ:
             if callable(what):
@@ -1030,23 +1214,25 @@ def _module_name(self, fname: str) -> str:
             return fname
         return os.path.relpath(fname, self._schema_dir)
 
-    def _make_module(self, fname):
+    def _make_module(self, fname: str) -> QAPISchemaModule:
         name = self._module_name(fname)
         if name not in self._module_dict:
             self._module_dict[name] = QAPISchemaModule(name)
         return self._module_dict[name]
 
-    def module_by_fname(self, fname):
+    def module_by_fname(self, fname: str) -> QAPISchemaModule:
         name = self._module_name(fname)
         return self._module_dict[name]
 
-    def _def_include(self, expr: QAPIExpression):
+    def _def_include(self, expr: QAPIExpression) -> None:
         include = expr['include']
         assert expr.doc is None
         self._def_entity(
             QAPISchemaInclude(self._make_module(include), expr.info))
 
-    def _def_builtin_type(self, name, json_type, c_type):
+    def _def_builtin_type(
+        self, name: str, json_type: str, c_type: str
+    ) -> None:
         self._def_entity(QAPISchemaBuiltinType(name, json_type, c_type))
         # Instantiating only the arrays that are actually used would
         # be nice, but we can't as long as their generated code
@@ -1054,7 +1240,7 @@ def _def_builtin_type(self, name, json_type, c_type):
         # schema.
         self._make_array_type(name, None)
 
-    def _def_predefineds(self):
+    def _def_predefineds(self) -> None:
         for t in [('str',    'string',  'char' + POINTER_SUFFIX),
                   ('number', 'number',  'double'),
                   ('int',    'int',     'int64_t'),
@@ -1083,30 +1269,51 @@ def _def_predefineds(self):
         self._def_entity(QAPISchemaEnumType('QType', None, None, None, None,
                                             qtype_values, 'QTYPE'))
 
-    def _make_features(self, features, info):
+    def _make_features(
+        self,
+        features: Optional[List[Dict[str, Any]]],
+        info: Optional[QAPISourceInfo],
+    ) -> List[QAPISchemaFeature]:
         if features is None:
             return []
         return [QAPISchemaFeature(f['name'], info,
                                   QAPISchemaIfCond(f.get('if')))
                 for f in features]
 
-    def _make_enum_member(self, name, ifcond, features, info):
+    def _make_enum_member(
+        self,
+        name: str,
+        ifcond: Optional[Union[str, Dict[str, Any]]],
+        features: Optional[List[Dict[str, Any]]],
+        info: Optional[QAPISourceInfo],
+    ) -> QAPISchemaEnumMember:
         return QAPISchemaEnumMember(name, info,
                                     QAPISchemaIfCond(ifcond),
                                     self._make_features(features, info))
 
-    def _make_enum_members(self, values, info):
+    def _make_enum_members(
+        self, values: List[Dict[str, Any]], info: Optional[QAPISourceInfo]
+    ) -> List[QAPISchemaEnumMember]:
         return [self._make_enum_member(v['name'], v.get('if'),
                                        v.get('features'), info)
                 for v in values]
 
-    def _make_array_type(self, element_type, info):
+    def _make_array_type(
+        self, element_type: str, info: Optional[QAPISourceInfo]
+    ) -> str:
         name = element_type + 'List'    # reserved by check_defn_name_str()
         if not self.lookup_type(name):
             self._def_entity(QAPISchemaArrayType(name, info, element_type))
         return name
 
-    def _make_implicit_object_type(self, name, info, ifcond, role, members):
+    def _make_implicit_object_type(
+        self,
+        name: str,
+        info: QAPISourceInfo,
+        ifcond: QAPISchemaIfCond,
+        role: str,
+        members: List[QAPISchemaObjectTypeMember],
+    ) -> Optional[str]:
         if not members:
             return None
         # See also QAPISchemaObjectTypeMember.describe()
@@ -1122,7 +1329,7 @@ def _make_implicit_object_type(self, name, info, ifcond, role, members):
                 name, info, None, ifcond, None, None, members, None))
         return name
 
-    def _def_enum_type(self, expr: QAPIExpression):
+    def _def_enum_type(self, expr: QAPIExpression) -> None:
         name = expr['enum']
         data = expr['data']
         prefix = expr.get('prefix')
@@ -1133,7 +1340,14 @@ def _def_enum_type(self, expr: QAPIExpression):
             name, info, expr.doc, ifcond, features,
             self._make_enum_members(data, info), prefix))
 
-    def _make_member(self, name, typ, ifcond, features, info):
+    def _make_member(
+        self,
+        name: str,
+        typ: Union[List[str], str],
+        ifcond: QAPISchemaIfCond,
+        features: Optional[List[Dict[str, Any]]],
+        info: QAPISourceInfo,
+    ) -> QAPISchemaObjectTypeMember:
         optional = False
         if name.startswith('*'):
             name = name[1:]
@@ -1144,13 +1358,17 @@ def _make_member(self, name, typ, ifcond, features, info):
         return QAPISchemaObjectTypeMember(name, info, typ, optional, ifcond,
                                           self._make_features(features, info))
 
-    def _make_members(self, data, info):
+    def _make_members(
+        self,
+        data: Dict[str, Any],
+        info: QAPISourceInfo,
+    ) -> List[QAPISchemaObjectTypeMember]:
         return [self._make_member(key, value['type'],
                                   QAPISchemaIfCond(value.get('if')),
                                   value.get('features'), info)
                 for (key, value) in data.items()]
 
-    def _def_struct_type(self, expr: QAPIExpression):
+    def _def_struct_type(self, expr: QAPIExpression) -> None:
         name = expr['struct']
         base = expr.get('base')
         data = expr['data']
@@ -1162,13 +1380,19 @@ def _def_struct_type(self, expr: QAPIExpression):
             self._make_members(data, info),
             None))
 
-    def _make_variant(self, case, typ, ifcond, info):
+    def _make_variant(
+        self,
+        case: str,
+        typ: str,
+        ifcond: QAPISchemaIfCond,
+        info: QAPISourceInfo,
+    ) -> QAPISchemaVariant:
         if isinstance(typ, list):
             assert len(typ) == 1
             typ = self._make_array_type(typ[0], info)
         return QAPISchemaVariant(case, info, typ, ifcond)
 
-    def _def_union_type(self, expr: QAPIExpression):
+    def _def_union_type(self, expr: QAPIExpression) -> None:
         name = expr['union']
         base = expr['base']
         tag_name = expr['discriminator']
@@ -1193,7 +1417,7 @@ def _def_union_type(self, expr: QAPIExpression):
                                  QAPISchemaVariants(
                                      tag_name, info, None, variants)))
 
-    def _def_alternate_type(self, expr: QAPIExpression):
+    def _def_alternate_type(self, expr: QAPIExpression) -> None:
         name = expr['alternate']
         data = expr['data']
         assert isinstance(data, dict)
@@ -1211,7 +1435,7 @@ def _def_alternate_type(self, expr: QAPIExpression):
                 name, info, expr.doc, ifcond, features,
                 QAPISchemaVariants(None, info, tag_member, variants)))
 
-    def _def_command(self, expr: QAPIExpression):
+    def _def_command(self, expr: QAPIExpression) -> None:
         name = expr['command']
         data = expr.get('data')
         rets = expr.get('returns')
@@ -1237,7 +1461,7 @@ def _def_command(self, expr: QAPIExpression):
                                            boxed, allow_oob, allow_preconfig,
                                            coroutine))
 
-    def _def_event(self, expr: QAPIExpression):
+    def _def_event(self, expr: QAPIExpression) -> None:
         name = expr['event']
         data = expr.get('data')
         boxed = expr.get('boxed', False)
@@ -1251,7 +1475,7 @@ def _def_event(self, expr: QAPIExpression):
         self._def_entity(QAPISchemaEvent(name, info, expr.doc, ifcond,
                                          features, data, boxed))
 
-    def _def_exprs(self, exprs):
+    def _def_exprs(self, exprs: List[QAPIExpression]) -> None:
         for expr in exprs:
             if 'enum' in expr:
                 self._def_enum_type(expr)
@@ -1270,7 +1494,7 @@ def _def_exprs(self, exprs):
             else:
                 assert False
 
-    def check(self):
+    def check(self) -> None:
         for ent in self._entity_list:
             ent.check(self)
             ent.connect_doc()
@@ -1278,7 +1502,7 @@ def check(self):
         for ent in self._entity_list:
             ent.set_module(self)
 
-    def visit(self, visitor):
+    def visit(self, visitor: QAPISchemaVisitor) -> None:
         visitor.visit_begin(self)
         for mod in self._module_dict.values():
             mod.visit(visitor)
-- 
2.41.0
Re: [PATCH 16/19] qapi/schema: add type hints
Posted by Markus Armbruster 1 year ago
John Snow <jsnow@redhat.com> writes:

> This patch only adds type hints, which aren't utilized at runtime and
> don't change the behavior of this module in any way.
>
> In a scant few locations, type hints are removed where no longer
> necessary due to inference power from typing all of the rest of
> creation; and any type hints that no longer need string quotes are
> changed.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/schema.py | 554 +++++++++++++++++++++++++++++------------
>  1 file changed, 389 insertions(+), 165 deletions(-)
>
> diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
> index ce5b01b3182..5d19b59def0 100644
> --- a/scripts/qapi/schema.py
> +++ b/scripts/qapi/schema.py
> @@ -15,10 +15,20 @@
>  # TODO catching name collisions in generated code would be nice
>  # pylint: disable=too-many-lines
>  
> +from __future__ import annotations
> +
>  from collections import OrderedDict
>  import os
>  import re
> -from typing import List, Optional, cast
> +from typing import (
> +    Any,
> +    Callable,
> +    Dict,
> +    List,
> +    Optional,
> +    Union,
> +    cast,
> +)
>  
>  from .common import (
>      POINTER_SUFFIX,
> @@ -30,39 +40,50 @@
>  )
>  from .error import QAPIError, QAPISemError, QAPISourceError
>  from .expr import check_exprs
> -from .parser import QAPIExpression, QAPISchemaParser
> +from .parser import QAPIDoc, QAPIExpression, QAPISchemaParser
> +from .source import QAPISourceInfo
>  
>  
>  class QAPISchemaIfCond:
> -    def __init__(self, ifcond=None):
> +    def __init__(
> +        self,
> +        ifcond: Optional[Union[str, Dict[str, object]]] = None,

Once again, we approximate a recursive type with Dict[str, object].

> +    ) -> None:
>          self.ifcond = ifcond
>  
> -    def _cgen(self):
> +    def _cgen(self) -> str:
>          return cgen_ifcond(self.ifcond)
>  
> -    def gen_if(self):
> +    def gen_if(self) -> str:
>          return gen_if(self._cgen())
>  
> -    def gen_endif(self):
> +    def gen_endif(self) -> str:
>          return gen_endif(self._cgen())
>  
> -    def docgen(self):
> +    def docgen(self) -> str:
>          return docgen_ifcond(self.ifcond)
>  
> -    def is_present(self):
> +    def is_present(self) -> bool:
>          return bool(self.ifcond)
>  
>  
>  class QAPISchemaEntity:
> -    meta: Optional[str] = None
> +    meta: str

This is more than just a type hint, you also drop the initial value.
Which is fine; QAPISchemaEntity is abstract, and the concrete subtypes
all initialize it.

Separate patch so this patch's commit message doesn't lie.

>  
> -    def __init__(self, name: str, info, doc, ifcond=None, features=None):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        doc: Optional[QAPIDoc],
> +        ifcond: Optional[QAPISchemaIfCond] = None,
> +        features: Optional[List[QAPISchemaFeature]] = None,
> +    ):
>          assert name is None or isinstance(name, str)
>          for f in features or []:
>              assert isinstance(f, QAPISchemaFeature)
>              f.set_defined_in(name)
>          self.name = name
> -        self._module = None
> +        self._module: Optional[QAPISchemaModule] = None
>          # 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
> @@ -74,102 +95,162 @@ def __init__(self, name: str, info, doc, ifcond=None, features=None):
>          self.features = features or []
>          self._checked = False
>  
> -    def __repr__(self):
> +    def __repr__(self) -> str:
>          if self.name is None:
>              return "<%s at 0x%x>" % (type(self).__name__, id(self))
>          return "<%s:%s at 0x%x>" % (type(self).__name__, self.name, id(self))
>  
> -    def c_name(self):
> +    def c_name(self) -> str:
>          return c_name(self.name)
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          # pylint: disable=unused-argument
>          assert not self._checked
> -        seen = {}
> +        seen: Dict[str, QAPISchemaMember] = {}
>          for f in self.features:
>              f.check_clash(self.info, seen)
>          self._checked = True
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          doc = doc or self.doc
>          if doc:
>              for f in self.features:
>                  doc.connect_feature(f)
>  
> -    def check_doc(self):
> +    def check_doc(self) -> None:
>          if self.doc:
>              self.doc.check()
>  
> -    def _set_module(self, schema, info):
> +    def _set_module(
> +        self, schema: QAPISchema, info: Optional[QAPISourceInfo]
> +    ) -> None:
>          assert self._checked
>          fname = info.fname if info else QAPISchemaModule.BUILTIN_MODULE_NAME
>          self._module = schema.module_by_fname(fname)
>          self._module.add_entity(self)
>  
> -    def set_module(self, schema):
> +    def set_module(self, schema: QAPISchema) -> None:
>          self._set_module(schema, self.info)
>  
>      @property
> -    def ifcond(self):
> +    def ifcond(self) -> QAPISchemaIfCond:
>          assert self._checked
>          return self._ifcond
>  
> -    def is_implicit(self):
> +    def is_implicit(self) -> bool:
>          return not self.info
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          # pylint: disable=unused-argument
>          assert self._checked
>  
> -    def describe(self):
> +    def describe(self) -> str:
>          assert self.meta
>          return "%s '%s'" % (self.meta, self.name)
>  
>  
>  class QAPISchemaVisitor:
> -    def visit_begin(self, schema):
> +    def visit_begin(self, schema: QAPISchema) -> None:
>          pass
>  
> -    def visit_end(self):
> +    def visit_end(self) -> None:
>          pass
>  
> -    def visit_module(self, name):
> +    def visit_module(self, name: str) -> None:
>          pass
>  
> -    def visit_needed(self, entity):
> +    def visit_needed(self, entity: QAPISchemaEntity) -> bool:
>          # pylint: disable=unused-argument
>          # Default to visiting everything
>          return True
>  
> -    def visit_include(self, name, info):
> +    def visit_include(self, name: str, info: Optional[QAPISourceInfo]) -> None:

Long line.

>          pass
>  
> -    def visit_builtin_type(self, name, info, json_type):
> +    def visit_builtin_type(
> +        self, name: str, info: Optional[QAPISourceInfo], json_type: str
> +    ) -> None:
>          pass
>  
> -    def visit_enum_type(self, name, info, ifcond, features, members, prefix):
> +    def visit_enum_type(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        members: List[QAPISchemaEnumMember],
> +        prefix: Optional[str],
> +    ) -> None:
>          pass
>  
> -    def visit_array_type(self, name, info, ifcond, element_type):
> +    def visit_array_type(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        element_type: QAPISchemaType,
> +    ) -> None:
>          pass
>  
> -    def visit_object_type(self, name, info, ifcond, features,
> -                          base, members, variants):
> +    def visit_object_type(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        base: Optional[QAPISchemaObjectType],
> +        members: List[QAPISchemaObjectTypeMember],
> +        variants: Optional[QAPISchemaVariants],
> +    ) -> None:
>          pass
>  
> -    def visit_object_type_flat(self, name, info, ifcond, features,
> -                               members, variants):
> +    def visit_object_type_flat(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        members: List[QAPISchemaObjectTypeMember],
> +        variants: Optional[QAPISchemaVariants],
> +    ) -> None:
>          pass
>  
> -    def visit_alternate_type(self, name, info, ifcond, features, variants):
> +    def visit_alternate_type(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        variants: QAPISchemaVariants,
> +    ) -> None:
>          pass
>  
> -    def visit_command(self, name, info, ifcond, features,
> -                      arg_type, ret_type, gen, success_response, boxed,
> -                      allow_oob, allow_preconfig, coroutine):
> +    def visit_command(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        arg_type: Optional[QAPISchemaObjectType],
> +        ret_type: Optional[QAPISchemaType],
> +        gen: bool,
> +        success_response: bool,
> +        boxed: bool,
> +        allow_oob: bool,
> +        allow_preconfig: bool,
> +        coroutine: bool,
> +    ) -> None:
>          pass
>  
> -    def visit_event(self, name, info, ifcond, features, arg_type, boxed):
> +    def visit_event(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        arg_type: Optional[QAPISchemaObjectType],
> +        boxed: bool,
> +    ) -> None:
>          pass
>  
>  
> @@ -177,9 +258,9 @@ class QAPISchemaModule:
>  
>      BUILTIN_MODULE_NAME = './builtin'
>  
> -    def __init__(self, name):
> +    def __init__(self, name: str):
>          self.name = name
> -        self._entity_list = []
> +        self._entity_list: List[QAPISchemaEntity] = []
>  
>      @staticmethod
>      def is_system_module(name: str) -> bool:
> @@ -208,10 +289,10 @@ def is_builtin_module(cls, name: str) -> bool:
>          """
>          return name == cls.BUILTIN_MODULE_NAME
>  
> -    def add_entity(self, ent):
> +    def add_entity(self, ent: QAPISchemaEntity) -> None:
>          self._entity_list.append(ent)
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          visitor.visit_module(self.name)
>          for entity in self._entity_list:
>              if visitor.visit_needed(entity):
> @@ -219,13 +300,13 @@ def visit(self, visitor):
>  
>  
>  class QAPISchemaInclude(QAPISchemaEntity):
> -    def __init__(self, sub_module, info):
> +    def __init__(self, sub_module: QAPISchemaModule, info: QAPISourceInfo):
>          # Includes are internal entity objects; and may occur multiple times
>          name = f"q_include_{info.fname}:{info.line}"
>          super().__init__(name, info, None)
>          self._sub_module = sub_module
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_include(self._sub_module.name, self.info)
>  
> @@ -237,17 +318,17 @@ def c_type(self) -> str:
>          raise NotImplementedError()
>  
>      # Return the C type to be used in a parameter list.
> -    def c_param_type(self):
> +    def c_param_type(self) -> str:
>          return self.c_type()
>  
>      # Return the C type to be used where we suppress boxing.
> -    def c_unboxed_type(self):
> +    def c_unboxed_type(self) -> str:
>          return self.c_type()
>  
>      def json_type(self) -> str:
>          raise NotImplementedError()
>  
> -    def alternate_qtype(self):
> +    def alternate_qtype(self) -> Optional[str]:
>          json2qtype = {
>              'null':    'QTYPE_QNULL',
>              'string':  'QTYPE_QSTRING',
> @@ -259,17 +340,17 @@ def alternate_qtype(self):
>          }
>          return json2qtype.get(self.json_type())
>  
> -    def doc_type(self):
> +    def doc_type(self) -> Optional[str]:
>          if self.is_implicit():
>              return None
>          return self.name
>  
> -    def need_has_if_optional(self):
> +    def need_has_if_optional(self) -> bool:
>          # When FOO is a pointer, has_FOO == !!FOO, i.e. has_FOO is redundant.
>          # Except for arrays; see QAPISchemaArrayType.need_has_if_optional().
>          return not self.c_type().endswith(POINTER_SUFFIX)
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          super().check(schema)
>          for feat in self.features:
>              if feat.is_special():
> @@ -277,7 +358,7 @@ def check(self, schema):
>                      self.info,
>                      f"feature '{feat.name}' is not supported for types")
>  
> -    def describe(self):
> +    def describe(self) -> str:
>          assert self.meta
>          return "%s type '%s'" % (self.meta, self.name)
>  
> @@ -285,7 +366,7 @@ def describe(self):
>  class QAPISchemaBuiltinType(QAPISchemaType):
>      meta = 'built-in'
>  
> -    def __init__(self, name, json_type, c_type):
> +    def __init__(self, name: str, json_type: str, c_type: str):
>          super().__init__(name, None, None)
>          assert not c_type or isinstance(c_type, str)
>          assert json_type in ('string', 'number', 'int', 'boolean', 'null',
> @@ -293,24 +374,24 @@ def __init__(self, name, json_type, c_type):
>          self._json_type_name = json_type
>          self._c_type_name = c_type
>  
> -    def c_name(self):
> +    def c_name(self) -> str:
>          return self.name
>  
> -    def c_type(self):
> +    def c_type(self) -> str:
>          return self._c_type_name
>  
> -    def c_param_type(self):
> +    def c_param_type(self) -> str:
>          if self.name == 'str':
>              return 'const ' + self._c_type_name
>          return self._c_type_name
>  
> -    def json_type(self):
> +    def json_type(self) -> str:
>          return self._json_type_name
>  
> -    def doc_type(self):
> +    def doc_type(self) -> str:
>          return self.json_type()
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_builtin_type(self.name, self.info, self.json_type())
>  
> @@ -318,7 +399,16 @@ def visit(self, visitor):
>  class QAPISchemaEnumType(QAPISchemaType):
>      meta = 'enum'
>  
> -    def __init__(self, name, info, doc, ifcond, features, members, prefix):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        doc: Optional[QAPIDoc],
> +        ifcond: Optional[QAPISchemaIfCond],
> +        features: Optional[List[QAPISchemaFeature]],
> +        members: List[QAPISchemaEnumMember],
> +        prefix: Optional[str],
> +    ):
>          super().__init__(name, info, doc, ifcond, features)
>          for m in members:
>              assert isinstance(m, QAPISchemaEnumMember)
> @@ -327,32 +417,32 @@ def __init__(self, name, info, doc, ifcond, features, members, prefix):
>          self.members = members
>          self.prefix = prefix
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          super().check(schema)
> -        seen = {}
> +        seen: Dict[str, QAPISchemaMember] = {}
>          for m in self.members:
>              m.check_clash(self.info, seen)
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          super().connect_doc(doc)
>          doc = doc or self.doc
>          for m in self.members:
>              m.connect_doc(doc)
>  
> -    def is_implicit(self):
> +    def is_implicit(self) -> bool:
>          # See QAPISchema._def_predefineds()
>          return self.name == 'QType'
>  
> -    def c_type(self):
> +    def c_type(self) -> str:
>          return c_name(self.name)
>  
> -    def member_names(self):
> +    def member_names(self) -> List[str]:
>          return [m.name for m in self.members]
>  
> -    def json_type(self):
> +    def json_type(self) -> str:
>          return 'string'
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_enum_type(
>              self.name, self.info, self.ifcond, self.features,
> @@ -362,7 +452,9 @@ def visit(self, visitor):
>  class QAPISchemaArrayType(QAPISchemaType):
>      meta = 'array'
>  
> -    def __init__(self, name, info, element_type):
> +    def __init__(
> +        self, name: str, info: Optional[QAPISourceInfo], element_type: str
> +    ):
>          super().__init__(name, info, None)
>          assert isinstance(element_type, str)
>          self._element_type_name = element_type
> @@ -377,12 +469,12 @@ def element_type(self) -> QAPISchemaType:
>              )
>          return self._element_type
>  
> -    def need_has_if_optional(self):
> +    def need_has_if_optional(self) -> bool:
>          # When FOO is an array, we still need has_FOO to distinguish
>          # absent (!has_FOO) from present and empty (has_FOO && !FOO).
>          return True
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          super().check(schema)
>  
>          if self.info:
> @@ -396,42 +488,51 @@ def check(self, schema):
>          )
>          assert not isinstance(self.element_type, QAPISchemaArrayType)
>  
> -    def set_module(self, schema):
> +    def set_module(self, schema: QAPISchema) -> None:
>          self._set_module(schema, self.element_type.info)
>  
>      @property
> -    def ifcond(self):
> +    def ifcond(self) -> QAPISchemaIfCond:
>          assert self._checked
>          return self.element_type.ifcond
>  
> -    def is_implicit(self):
> +    def is_implicit(self) -> bool:
>          return True
>  
> -    def c_type(self):
> +    def c_type(self) -> str:
>          return c_name(self.name) + POINTER_SUFFIX
>  
> -    def json_type(self):
> +    def json_type(self) -> str:
>          return 'array'
>  
> -    def doc_type(self):
> +    def doc_type(self) -> Optional[str]:
>          elt_doc_type = self.element_type.doc_type()
>          if not elt_doc_type:
>              return None
>          return 'array of ' + elt_doc_type
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_array_type(self.name, self.info, self.ifcond,
>                                   self.element_type)
>  
> -    def describe(self):
> +    def describe(self) -> str:
>          assert self.meta
>          return "%s type ['%s']" % (self.meta, self._element_type_name)
>  
>  
>  class QAPISchemaObjectType(QAPISchemaType):
> -    def __init__(self, name, info, doc, ifcond, features,
> -                 base, local_members, variants):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        doc: Optional[QAPIDoc],
> +        ifcond: Optional[QAPISchemaIfCond],
> +        features: Optional[List[QAPISchemaFeature]],
> +        base: Optional[str],
> +        local_members: List[QAPISchemaObjectTypeMember],
> +        variants: Optional[QAPISchemaVariants],
> +    ):
>          # struct has local_members, optional base, and no variants
>          # union has base, variants, and no local_members
>          super().__init__(name, info, doc, ifcond, features)
> @@ -450,7 +551,7 @@ def __init__(self, name, info, doc, ifcond, features,
>          self.members: List[QAPISchemaObjectTypeMember] = []
>          self._checking = False
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          # This calls another type T's .check() exactly when the C
>          # struct emitted by gen_object() contains that T's C struct
>          # (pointers don't count).
> @@ -496,14 +597,18 @@ def check(self, schema):
>      # Check that the members of this type do not cause duplicate JSON members,
>      # and update seen to track the members seen so far. Report any errors
>      # on behalf of info, which is not necessarily self.info
> -    def check_clash(self, info, seen):
> +    def check_clash(
> +        self,
> +        info: Optional[QAPISourceInfo],
> +        seen: Dict[str, QAPISchemaMember],
> +    ) -> None:
>          assert self._checked
>          for m in self.members:
>              m.check_clash(info, seen)
>          if self.variants:
>              self.variants.check_clash(info, seen)
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          super().connect_doc(doc)
>          doc = doc or self.doc
>          if self.base and self.base.is_implicit():
> @@ -511,34 +616,34 @@ def connect_doc(self, doc=None):
>          for m in self.local_members:
>              m.connect_doc(doc)
>  
> -    def is_implicit(self):
> +    def is_implicit(self) -> bool:
>          # See QAPISchema._make_implicit_object_type(), as well as
>          # _def_predefineds()
>          return self.name.startswith('q_')
>  
> -    def is_empty(self):
> +    def is_empty(self) -> bool:
>          assert self.members is not None
>          return not self.members and not self.variants
>  
> -    def has_conditional_members(self):
> +    def has_conditional_members(self) -> bool:
>          assert self.members is not None
>          return any(m.ifcond.is_present() for m in self.members)
>  
> -    def c_name(self):
> +    def c_name(self) -> str:
>          assert self.name != 'q_empty'
>          return super().c_name()
>  
> -    def c_type(self):
> +    def c_type(self) -> str:
>          assert not self.is_implicit()
>          return c_name(self.name) + POINTER_SUFFIX
>  
> -    def c_unboxed_type(self):
> +    def c_unboxed_type(self) -> str:
>          return c_name(self.name)
>  
> -    def json_type(self):
> +    def json_type(self) -> str:
>          return 'object'
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_object_type(
>              self.name, self.info, self.ifcond, self.features,
> @@ -551,7 +656,15 @@ def visit(self, visitor):
>  class QAPISchemaAlternateType(QAPISchemaType):
>      meta = 'alternate'
>  
> -    def __init__(self, name, info, doc, ifcond, features, variants):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        doc: Optional[QAPIDoc],
> +        ifcond: Optional[QAPISchemaIfCond],
> +        features: List[QAPISchemaFeature],
> +        variants: QAPISchemaVariants,
> +    ):
>          super().__init__(name, info, doc, ifcond, features)
>          assert isinstance(variants, QAPISchemaVariants)
>          assert variants.tag_member
> @@ -559,7 +672,7 @@ def __init__(self, name, info, doc, ifcond, features, variants):
>          variants.tag_member.set_defined_in(self.name)
>          self.variants = variants
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          super().check(schema)
>          self.variants.tag_member.check(schema)
>          # Not calling self.variants.check_clash(), because there's nothing
> @@ -567,8 +680,8 @@ def check(self, schema):
>          self.variants.check(schema, {})
>          # Alternate branch names have no relation to the tag enum values;
>          # so we have to check for potential name collisions ourselves.
> -        seen = {}
> -        types_seen = {}
> +        seen: Dict[str, QAPISchemaMember] = {}
> +        types_seen: Dict[str, str] = {}
>          for v in self.variants.variants:
>              v.check_clash(self.info, seen)
>              qtype = v.type.alternate_qtype()
> @@ -597,26 +710,32 @@ def check(self, schema):
>                          % (v.describe(self.info), types_seen[qt]))
>                  types_seen[qt] = v.name
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          super().connect_doc(doc)
>          doc = doc or self.doc
>          for v in self.variants.variants:
>              v.connect_doc(doc)
>  
> -    def c_type(self):
> +    def c_type(self) -> str:
>          return c_name(self.name) + POINTER_SUFFIX
>  
> -    def json_type(self):
> +    def json_type(self) -> str:
>          return 'value'
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_alternate_type(
>              self.name, self.info, self.ifcond, self.features, self.variants)
>  
>  
>  class QAPISchemaVariants:
> -    def __init__(self, tag_name, info, tag_member, variants):
> +    def __init__(
> +        self,
> +        tag_name: Optional[str],
> +        info: QAPISourceInfo,
> +        tag_member: Optional[QAPISchemaObjectTypeMember],
> +        variants: List[QAPISchemaVariant],
> +    ):
>          # Unions pass tag_name but not tag_member.
>          # Alternates pass tag_member but not tag_name.
>          # After check(), tag_member is always set.
> @@ -627,11 +746,11 @@ def __init__(self, tag_name, info, tag_member, variants):
>              assert isinstance(v, QAPISchemaVariant)
>          self._tag_name = tag_name
>          self.info = info
> -        self._tag_member: Optional[QAPISchemaObjectTypeMember] = tag_member
> +        self._tag_member = tag_member

Appreciate your removal of now unnecessary type hints!

>          self.variants = variants
>  
>      @property
> -    def tag_member(self) -> 'QAPISchemaObjectTypeMember':
> +    def tag_member(self) -> QAPISchemaObjectTypeMember:

Is this a cleanup enabled by leaving Python 3.6 behind?

>          if self._tag_member is None:
>              raise RuntimeError(
>                  "QAPISchemaVariants has no tag_member property until "
> @@ -639,11 +758,13 @@ def tag_member(self) -> 'QAPISchemaObjectTypeMember':
>              )
>          return self._tag_member
>  
> -    def set_defined_in(self, name):
> +    def set_defined_in(self, name: str) -> None:
>          for v in self.variants:
>              v.set_defined_in(name)
>  
> -    def check(self, schema, seen):
> +    def check(
> +        self, schema: QAPISchema, seen: Dict[str, QAPISchemaMember]
> +    ) -> None:
>          if self._tag_name:      # union
>              # We need to narrow the member type:
>              tmp = seen.get(c_name(self._tag_name))
> @@ -713,7 +834,11 @@ def check(self, schema, seen):
>                          % (v.describe(self.info), v.type.describe()))
>                  v.type.check(schema)
>  
> -    def check_clash(self, info, seen):
> +    def check_clash(
> +        self,
> +        info: Optional[QAPISourceInfo],
> +        seen: Dict[str, QAPISchemaMember],
> +    ) -> None:
>          for v in self.variants:
>              # Reset seen map for each variant, since qapi names from one
>              # branch do not affect another branch
> @@ -725,18 +850,27 @@ class QAPISchemaMember:
>      """ Represents object members, enum members and features """
>      role = 'member'
>  
> -    def __init__(self, name, info, ifcond=None):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: Optional[QAPISchemaIfCond] = None,
> +    ):
>          assert isinstance(name, str)
>          self.name = name
>          self.info = info
>          self.ifcond = ifcond or QAPISchemaIfCond()
> -        self.defined_in = None
> +        self.defined_in: Optional[str] = None
>  
> -    def set_defined_in(self, name):
> +    def set_defined_in(self, name: str) -> None:
>          assert not self.defined_in
>          self.defined_in = name
>  
> -    def check_clash(self, info, seen):
> +    def check_clash(
> +        self,
> +        info: Optional[QAPISourceInfo],
> +        seen: Dict[str, QAPISchemaMember],
> +    ) -> None:
>          cname = c_name(self.name)
>          if cname in seen:
>              raise QAPISemError(
> @@ -745,11 +879,11 @@ def check_clash(self, info, seen):
>                  % (self.describe(info), seen[cname].describe(info)))
>          seen[cname] = self
>  
> -    def connect_doc(self, doc):
> +    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
>          if doc:
>              doc.connect_member(self)
>  
> -    def describe(self, info):
> +    def describe(self, info: Optional[QAPISourceInfo]) -> str:
>          role = self.role
>          meta = 'type'
>          defined_in = self.defined_in
> @@ -781,14 +915,20 @@ def describe(self, info):
>  class QAPISchemaEnumMember(QAPISchemaMember):
>      role = 'value'
>  
> -    def __init__(self, name, info, ifcond=None, features=None):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        ifcond: Optional[QAPISchemaIfCond] = None,
> +        features: Optional[List[QAPISchemaFeature]] = None,
> +    ):
>          super().__init__(name, info, ifcond)
>          for f in features or []:
>              assert isinstance(f, QAPISchemaFeature)
>              f.set_defined_in(name)
>          self.features = features or []
>  
> -    def connect_doc(self, doc):
> +    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
>          super().connect_doc(doc)
>          if doc:
>              for f in self.features:
> @@ -798,12 +938,20 @@ def connect_doc(self, doc):
>  class QAPISchemaFeature(QAPISchemaMember):
>      role = 'feature'
>  
> -    def is_special(self):
> +    def is_special(self) -> bool:
>          return self.name in ('deprecated', 'unstable')
>  
>  
>  class QAPISchemaObjectTypeMember(QAPISchemaMember):
> -    def __init__(self, name, info, typ, optional, ifcond=None, features=None):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        typ: str,
> +        optional: bool,
> +        ifcond: Optional[QAPISchemaIfCond] = None,
> +        features: Optional[List[QAPISchemaFeature]] = None,
> +    ):
>          super().__init__(name, info, ifcond)
>          assert isinstance(typ, str)
>          assert isinstance(optional, bool)
> @@ -815,19 +963,19 @@ def __init__(self, name, info, typ, optional, ifcond=None, features=None):
>          self.optional = optional
>          self.features = features or []
>  
> -    def need_has(self):
> +    def need_has(self) -> bool:
>          assert self.type
>          return self.optional and self.type.need_has_if_optional()
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          assert self.defined_in
>          self.type = schema.resolve_type(self._type_name, self.info,
>                                          self.describe)
> -        seen = {}
> +        seen: Dict[str, QAPISchemaMember] = {}
>          for f in self.features:
>              f.check_clash(self.info, seen)
>  
> -    def connect_doc(self, doc):
> +    def connect_doc(self, doc: Optional[QAPIDoc]) -> None:
>          super().connect_doc(doc)
>          if doc:
>              for f in self.features:
> @@ -837,24 +985,42 @@ def connect_doc(self, doc):
>  class QAPISchemaVariant(QAPISchemaObjectTypeMember):
>      role = 'branch'
>  
> -    def __init__(self, name, info, typ, ifcond=None):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        typ: str,
> +        ifcond: QAPISchemaIfCond,
> +    ):
>          super().__init__(name, info, typ, False, ifcond)
>  
>  
>  class QAPISchemaCommand(QAPISchemaEntity):
>      meta = 'command'
>  
> -    def __init__(self, name, info, doc, ifcond, features,
> -                 arg_type, ret_type,
> -                 gen, success_response, boxed, allow_oob, allow_preconfig,
> -                 coroutine):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        doc: Optional[QAPIDoc],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        arg_type: Optional[str],
> +        ret_type: Optional[str],
> +        gen: bool,
> +        success_response: bool,
> +        boxed: bool,
> +        allow_oob: bool,
> +        allow_preconfig: bool,
> +        coroutine: bool,
> +    ):
>          super().__init__(name, info, doc, ifcond, features)
>          assert not arg_type or isinstance(arg_type, str)
>          assert not ret_type or isinstance(ret_type, str)
>          self._arg_type_name = arg_type
> -        self.arg_type = None
> +        self.arg_type: Optional[QAPISchemaObjectType] = None
>          self._ret_type_name = ret_type
> -        self.ret_type = None
> +        self.ret_type: Optional[QAPISchemaType] = None
>          self.gen = gen
>          self.success_response = success_response
>          self.boxed = boxed
> @@ -862,7 +1028,7 @@ def __init__(self, name, info, doc, ifcond, features,
>          self.allow_preconfig = allow_preconfig
>          self.coroutine = coroutine
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          assert self.info is not None
>          super().check(schema)
>          if self._arg_type_name:
> @@ -897,14 +1063,14 @@ def check(self, schema):
>                          "command's 'returns' cannot take %s"
>                          % self.ret_type.describe())
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          super().connect_doc(doc)
>          doc = doc or self.doc
>          if doc:
>              if self.arg_type and self.arg_type.is_implicit():
>                  self.arg_type.connect_doc(doc)
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_command(
>              self.name, self.info, self.ifcond, self.features,
> @@ -916,14 +1082,23 @@ def visit(self, visitor):
>  class QAPISchemaEvent(QAPISchemaEntity):
>      meta = 'event'
>  
> -    def __init__(self, name, info, doc, ifcond, features, arg_type, boxed):
> +    def __init__(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        doc: Optional[QAPIDoc],
> +        ifcond: QAPISchemaIfCond,
> +        features: List[QAPISchemaFeature],
> +        arg_type: Optional[str],
> +        boxed: bool,
> +    ):
>          super().__init__(name, info, doc, ifcond, features)
>          assert not arg_type or isinstance(arg_type, str)
>          self._arg_type_name = arg_type
> -        self.arg_type = None
> +        self.arg_type: Optional[QAPISchemaObjectType] = None
>          self.boxed = boxed
>  
> -    def check(self, schema):
> +    def check(self, schema: QAPISchema) -> None:
>          super().check(schema)
>          if self._arg_type_name:
>              typ = schema.resolve_type(
> @@ -945,14 +1120,14 @@ def check(self, schema):
>                      self.info,
>                      "conditional event arguments require 'boxed': true")
>  
> -    def connect_doc(self, doc=None):
> +    def connect_doc(self, doc: Optional[QAPIDoc] = None) -> None:
>          super().connect_doc(doc)
>          doc = doc or self.doc
>          if doc:
>              if self.arg_type and self.arg_type.is_implicit():
>                  self.arg_type.connect_doc(doc)
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          super().visit(visitor)
>          visitor.visit_event(
>              self.name, self.info, self.ifcond, self.features,
> @@ -960,7 +1135,7 @@ def visit(self, visitor):
>  
>  
>  class QAPISchema:
> -    def __init__(self, fname):
> +    def __init__(self, fname: str):
>          self.fname = fname
>  
>          try:
> @@ -972,9 +1147,9 @@ def __init__(self, fname):
>  
>          exprs = check_exprs(parser.exprs)
>          self.docs = parser.docs
> -        self._entity_list = []
> -        self._entity_dict = {}
> -        self._module_dict = OrderedDict()
> +        self._entity_list: List[QAPISchemaEntity] = []
> +        self._entity_dict: Dict[str, QAPISchemaEntity] = {}
> +        self._module_dict: Dict[str, QAPISchemaModule] = OrderedDict()

Apropos OrderedDict: plain dict guarantees insertion order since Python
3.7.  We should look into switching from OrderedDict to dict.  Not in
this patch, of course, and no need to do it in this series.

>          self._schema_dir = os.path.dirname(fname)
>          self._make_module(QAPISchemaModule.BUILTIN_MODULE_NAME)
>          self._make_module(fname)
> @@ -984,7 +1159,7 @@ def __init__(self, fname):
>          self._def_exprs(exprs)
>          self.check()
>  
> -    def _def_entity(self, ent):
> +    def _def_entity(self, ent: QAPISchemaEntity) -> None:
>          # Only the predefined types are allowed to not have info
>          assert ent.info or self._predefining
>          self._entity_list.append(ent)
> @@ -1003,7 +1178,11 @@ def _def_entity(self, ent):
>                  ent.info, "%s is already defined" % other_ent.describe())
>          self._entity_dict[ent.name] = ent
>  
> -    def lookup_entity(self, name, typ=None):
> +    def lookup_entity(
> +        self,
> +        name: str,
> +        typ: Optional[type] = None,
> +    ) -> Optional[QAPISchemaEntity]:
>          ent = self._entity_dict.get(name)
>          if typ and not isinstance(ent, typ):
>              return None
> @@ -1016,7 +1195,12 @@ def lookup_type(self, name: str) -> Optional[QAPISchemaType]:
>          assert isinstance(typ, QAPISchemaType)
>          return typ
>  
> -    def resolve_type(self, name, info, what):
> +    def resolve_type(
> +        self,
> +        name: str,
> +        info: Optional[QAPISourceInfo],
> +        what: Union[str, Callable[[Optional[QAPISourceInfo]], str]],
> +    ) -> QAPISchemaType:
>          typ = self.lookup_type(name)
>          if not typ:
>              if callable(what):
> @@ -1030,23 +1214,25 @@ def _module_name(self, fname: str) -> str:
>              return fname
>          return os.path.relpath(fname, self._schema_dir)
>  
> -    def _make_module(self, fname):
> +    def _make_module(self, fname: str) -> QAPISchemaModule:
>          name = self._module_name(fname)
>          if name not in self._module_dict:
>              self._module_dict[name] = QAPISchemaModule(name)
>          return self._module_dict[name]
>  
> -    def module_by_fname(self, fname):
> +    def module_by_fname(self, fname: str) -> QAPISchemaModule:
>          name = self._module_name(fname)
>          return self._module_dict[name]
>  
> -    def _def_include(self, expr: QAPIExpression):
> +    def _def_include(self, expr: QAPIExpression) -> None:
>          include = expr['include']
>          assert expr.doc is None
>          self._def_entity(
>              QAPISchemaInclude(self._make_module(include), expr.info))
>  
> -    def _def_builtin_type(self, name, json_type, c_type):
> +    def _def_builtin_type(
> +        self, name: str, json_type: str, c_type: str
> +    ) -> None:
>          self._def_entity(QAPISchemaBuiltinType(name, json_type, c_type))
>          # Instantiating only the arrays that are actually used would
>          # be nice, but we can't as long as their generated code
> @@ -1054,7 +1240,7 @@ def _def_builtin_type(self, name, json_type, c_type):
>          # schema.
>          self._make_array_type(name, None)
>  
> -    def _def_predefineds(self):
> +    def _def_predefineds(self) -> None:
>          for t in [('str',    'string',  'char' + POINTER_SUFFIX),
>                    ('number', 'number',  'double'),
>                    ('int',    'int',     'int64_t'),
> @@ -1083,30 +1269,51 @@ def _def_predefineds(self):
>          self._def_entity(QAPISchemaEnumType('QType', None, None, None, None,
>                                              qtype_values, 'QTYPE'))
>  
> -    def _make_features(self, features, info):
> +    def _make_features(
> +        self,
> +        features: Optional[List[Dict[str, Any]]],
> +        info: Optional[QAPISourceInfo],
> +    ) -> List[QAPISchemaFeature]:
>          if features is None:
>              return []
>          return [QAPISchemaFeature(f['name'], info,
>                                    QAPISchemaIfCond(f.get('if')))
>                  for f in features]
>  
> -    def _make_enum_member(self, name, ifcond, features, info):
> +    def _make_enum_member(
> +        self,
> +        name: str,
> +        ifcond: Optional[Union[str, Dict[str, Any]]],

Hmm.  In QAPISchemaIfCond.__init__(), you used Dict[str, object].  Any
particular reason for using Any here, and object there?

Out of curiosity: is there a practical difference between
Optional[Union[A, B]] and Union[None, A, B]?

> +        features: Optional[List[Dict[str, Any]]],
> +        info: Optional[QAPISourceInfo],
> +    ) -> QAPISchemaEnumMember:
>          return QAPISchemaEnumMember(name, info,
>                                      QAPISchemaIfCond(ifcond),
>                                      self._make_features(features, info))
>  
> -    def _make_enum_members(self, values, info):
> +    def _make_enum_members(
> +        self, values: List[Dict[str, Any]], info: Optional[QAPISourceInfo]
> +    ) -> List[QAPISchemaEnumMember]:
>          return [self._make_enum_member(v['name'], v.get('if'),
>                                         v.get('features'), info)
>                  for v in values]
>  
> -    def _make_array_type(self, element_type, info):
> +    def _make_array_type(
> +        self, element_type: str, info: Optional[QAPISourceInfo]
> +    ) -> str:
>          name = element_type + 'List'    # reserved by check_defn_name_str()
>          if not self.lookup_type(name):
>              self._def_entity(QAPISchemaArrayType(name, info, element_type))
>          return name
>  
> -    def _make_implicit_object_type(self, name, info, ifcond, role, members):
> +    def _make_implicit_object_type(
> +        self,
> +        name: str,
> +        info: QAPISourceInfo,
> +        ifcond: QAPISchemaIfCond,
> +        role: str,
> +        members: List[QAPISchemaObjectTypeMember],
> +    ) -> Optional[str]:
>          if not members:
>              return None
>          # See also QAPISchemaObjectTypeMember.describe()
> @@ -1122,7 +1329,7 @@ def _make_implicit_object_type(self, name, info, ifcond, role, members):
>                  name, info, None, ifcond, None, None, members, None))
>          return name
>  
> -    def _def_enum_type(self, expr: QAPIExpression):
> +    def _def_enum_type(self, expr: QAPIExpression) -> None:
>          name = expr['enum']
>          data = expr['data']
>          prefix = expr.get('prefix')
> @@ -1133,7 +1340,14 @@ def _def_enum_type(self, expr: QAPIExpression):
>              name, info, expr.doc, ifcond, features,
>              self._make_enum_members(data, info), prefix))
>  
> -    def _make_member(self, name, typ, ifcond, features, info):
> +    def _make_member(
> +        self,
> +        name: str,
> +        typ: Union[List[str], str],
> +        ifcond: QAPISchemaIfCond,
> +        features: Optional[List[Dict[str, Any]]],
> +        info: QAPISourceInfo,
> +    ) -> QAPISchemaObjectTypeMember:
>          optional = False
>          if name.startswith('*'):
>              name = name[1:]
> @@ -1144,13 +1358,17 @@ def _make_member(self, name, typ, ifcond, features, info):
>          return QAPISchemaObjectTypeMember(name, info, typ, optional, ifcond,
>                                            self._make_features(features, info))
>  
> -    def _make_members(self, data, info):
> +    def _make_members(
> +        self,
> +        data: Dict[str, Any],
> +        info: QAPISourceInfo,
> +    ) -> List[QAPISchemaObjectTypeMember]:
>          return [self._make_member(key, value['type'],
>                                    QAPISchemaIfCond(value.get('if')),
>                                    value.get('features'), info)
>                  for (key, value) in data.items()]
>  
> -    def _def_struct_type(self, expr: QAPIExpression):
> +    def _def_struct_type(self, expr: QAPIExpression) -> None:
>          name = expr['struct']
>          base = expr.get('base')
>          data = expr['data']
> @@ -1162,13 +1380,19 @@ def _def_struct_type(self, expr: QAPIExpression):
>              self._make_members(data, info),
>              None))
>  
> -    def _make_variant(self, case, typ, ifcond, info):
> +    def _make_variant(
> +        self,
> +        case: str,
> +        typ: str,
> +        ifcond: QAPISchemaIfCond,
> +        info: QAPISourceInfo,
> +    ) -> QAPISchemaVariant:
>          if isinstance(typ, list):
>              assert len(typ) == 1
>              typ = self._make_array_type(typ[0], info)
>          return QAPISchemaVariant(case, info, typ, ifcond)
>  
> -    def _def_union_type(self, expr: QAPIExpression):
> +    def _def_union_type(self, expr: QAPIExpression) -> None:
>          name = expr['union']
>          base = expr['base']
>          tag_name = expr['discriminator']
> @@ -1193,7 +1417,7 @@ def _def_union_type(self, expr: QAPIExpression):
>                                   QAPISchemaVariants(
>                                       tag_name, info, None, variants)))
>  
> -    def _def_alternate_type(self, expr: QAPIExpression):
> +    def _def_alternate_type(self, expr: QAPIExpression) -> None:
>          name = expr['alternate']
>          data = expr['data']
>          assert isinstance(data, dict)
> @@ -1211,7 +1435,7 @@ def _def_alternate_type(self, expr: QAPIExpression):
>                  name, info, expr.doc, ifcond, features,
>                  QAPISchemaVariants(None, info, tag_member, variants)))
>  
> -    def _def_command(self, expr: QAPIExpression):
> +    def _def_command(self, expr: QAPIExpression) -> None:
>          name = expr['command']
>          data = expr.get('data')
>          rets = expr.get('returns')
> @@ -1237,7 +1461,7 @@ def _def_command(self, expr: QAPIExpression):
>                                             boxed, allow_oob, allow_preconfig,
>                                             coroutine))
>  
> -    def _def_event(self, expr: QAPIExpression):
> +    def _def_event(self, expr: QAPIExpression) -> None:
>          name = expr['event']
>          data = expr.get('data')
>          boxed = expr.get('boxed', False)
> @@ -1251,7 +1475,7 @@ def _def_event(self, expr: QAPIExpression):
>          self._def_entity(QAPISchemaEvent(name, info, expr.doc, ifcond,
>                                           features, data, boxed))
>  
> -    def _def_exprs(self, exprs):
> +    def _def_exprs(self, exprs: List[QAPIExpression]) -> None:
>          for expr in exprs:
>              if 'enum' in expr:
>                  self._def_enum_type(expr)
> @@ -1270,7 +1494,7 @@ def _def_exprs(self, exprs):
>              else:
>                  assert False
>  
> -    def check(self):
> +    def check(self) -> None:
>          for ent in self._entity_list:
>              ent.check(self)
>              ent.connect_doc()
> @@ -1278,7 +1502,7 @@ def check(self):
>          for ent in self._entity_list:
>              ent.set_module(self)
>  
> -    def visit(self, visitor):
> +    def visit(self, visitor: QAPISchemaVisitor) -> None:
>          visitor.visit_begin(self)
>          for mod in self._module_dict.values():
>              mod.visit(visitor)

Big patch, impractical to review thoroughly, but I did what I could, and
since mypy is content, that should be good enough.