Merge remote-tracking branch 'remotes/armbru/tags/pull-qapi-2020-10-10' into staging

QAPI patches patches for 2020-10-10

# gpg: Signature made Sat 10 Oct 2020 10:43:14 BST
# gpg:                using RSA key 354BC8B3D7EB2A6B68674E5F3870B400EB918653
# gpg:                issuer "armbru@redhat.com"
# gpg: Good signature from "Markus Armbruster <armbru@redhat.com>" [full]
# gpg:                 aka "Markus Armbruster <armbru@pond.sub.org>" [full]
# Primary key fingerprint: 354B C8B3 D7EB 2A6B 6867  4E5F 3870 B400 EB91 8653

* remotes/armbru/tags/pull-qapi-2020-10-10: (34 commits)
  qapi/visit.py: add type hint annotations
  qapi/visit.py: remove unused parameters from gen_visit_object
  qapi/visit.py: assert tag_member contains a QAPISchemaEnumType
  qapi/types.py: remove one-letter variables
  qapi/types.py: add type hint annotations
  qapi/gen.py: delint with pylint
  qapi/gen.py: update write() to be more idiomatic
  qapi/gen.py: Remove unused parameter
  qapi/gen.py: add type hint annotations
  qapi/gen: Make _is_user_module() return bool
  qapi/source.py: delint with pylint
  qapi/source.py: add type hint annotations
  qapi/commands.py: add type hint annotations
  qapi/commands.py: Don't re-bind to variable of different type
  qapi/events.py: Move comments into docstrings
  qapi/events.py: add type hint annotations
  qapi: establish mypy type-checking baseline
  qapi/common.py: move build_params into gen.py
  qapi/common.py: Convert comments into docstrings, and elaborate
  qapi/common.py: add type hint annotations
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

16 files changed, 755 insertions, 295 deletions

diff --git a/scripts/qapi/.flake8 b/scripts/qapi/.flake8
new file mode 100644
index 0000000000..6b158c68b8
--- /dev/null
+++ b/scripts/qapi/.flake8
@@ -0,0 +1,2 @@
+[flake8]
+extend-ignore = E722  # Prefer pylint's bare-except checks to flake8's
diff --git a/scripts/qapi/.isort.cfg b/scripts/qapi/.isort.cfg
new file mode 100644
index 0000000000..643caa1fbd
--- /dev/null
+++ b/scripts/qapi/.isort.cfg
@@ -0,0 +1,7 @@
+[settings]
+force_grid_wrap=4
+force_sort_within_sections=True
+include_trailing_comma=True
+line_length=72
+lines_after_imports=2
+multi_line_output=3
diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
index 6e6fc94a14..50978090b4 100644
--- a/scripts/qapi/commands.py
+++ b/scripts/qapi/commands.py
@@ -13,11 +13,34 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from qapi.common import *
-from qapi.gen import QAPIGenCCode, QAPISchemaModularCVisitor, ifcontext
-
-
-def gen_command_decl(name, arg_type, boxed, ret_type):
+from typing import (
+    Dict,
+    List,
+    Optional,
+    Set,
+)
+
+from .common import c_name, mcgen
+from .gen import (
+    QAPIGenC,
+    QAPIGenCCode,
+    QAPISchemaModularCVisitor,
+    build_params,
+    ifcontext,
+)
+from .schema import (
+    QAPISchema,
+    QAPISchemaFeature,
+    QAPISchemaObjectType,
+    QAPISchemaType,
+)
+from .source import QAPISourceInfo
+
+
+def gen_command_decl(name: str,
+                     arg_type: Optional[QAPISchemaObjectType],
+                     boxed: bool,
+                     ret_type: Optional[QAPISchemaType]) -> str:
     return mcgen('''
 %(c_type)s qmp_%(c_name)s(%(params)s);
 ''',
@@ -26,7 +49,10 @@ def gen_command_decl(name, arg_type, boxed, ret_type):
                  params=build_params(arg_type, boxed, 'Error **errp'))
 
 
-def gen_call(name, arg_type, boxed, ret_type):
+def gen_call(name: str,
+             arg_type: Optional[QAPISchemaObjectType],
+             boxed: bool,
+             ret_type: Optional[QAPISchemaType]) -> str:
     ret = ''
 
     argstr = ''
@@ -62,10 +88,11 @@ def gen_call(name, arg_type, boxed, ret_type):
     return ret
 
 
-def gen_marshal_output(ret_type):
+def gen_marshal_output(ret_type: QAPISchemaType) -> str:
     return mcgen('''
 
-static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject **ret_out, Error **errp)
+static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in,
+                                QObject **ret_out, Error **errp)
 {
     Visitor *v;
 
@@ -82,19 +109,22 @@ static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject **ret_out,
                  c_type=ret_type.c_type(), c_name=ret_type.c_name())
 
 
-def build_marshal_proto(name):
+def build_marshal_proto(name: str) -> str:
     return ('void qmp_marshal_%s(QDict *args, QObject **ret, Error **errp)'
             % c_name(name))
 
 
-def gen_marshal_decl(name):
+def gen_marshal_decl(name: str) -> str:
     return mcgen('''
 %(proto)s;
 ''',
                  proto=build_marshal_proto(name))
 
 
-def gen_marshal(name, arg_type, boxed, ret_type):
+def gen_marshal(name: str,
+                arg_type: Optional[QAPISchemaObjectType],
+                boxed: bool,
+                ret_type: Optional[QAPISchemaType]) -> str:
     have_args = boxed or (arg_type and not arg_type.is_empty())
 
     ret = mcgen('''
@@ -176,8 +206,11 @@ out:
     return ret
 
 
-def gen_register_command(name, success_response, allow_oob, allow_preconfig,
-                         coroutine):
+def gen_register_command(name: str,
+                         success_response: bool,
+                         allow_oob: bool,
+                         allow_preconfig: bool,
+                         coroutine: bool) -> str:
     options = []
 
     if not success_response:
@@ -192,18 +225,16 @@ def gen_register_command(name, success_response, allow_oob, allow_preconfig,
     if not options:
         options = ['QCO_NO_OPTIONS']
 
-    options = " | ".join(options)
-
     ret = mcgen('''
     qmp_register_command(cmds, "%(name)s",
                          qmp_marshal_%(c_name)s, %(opts)s);
 ''',
                 name=name, c_name=c_name(name),
-                opts=options)
+                opts=" | ".join(options))
     return ret
 
 
-def gen_registry(registry, prefix):
+def gen_registry(registry: str, prefix: str) -> str:
     ret = mcgen('''
 
 void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds)
@@ -220,15 +251,14 @@ void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds)
 
 
 class QAPISchemaGenCommandVisitor(QAPISchemaModularCVisitor):
-
-    def __init__(self, prefix):
+    def __init__(self, prefix: str):
         super().__init__(
             prefix, 'qapi-commands',
             ' * Schema-defined QAPI/QMP commands', None, __doc__)
         self._regy = QAPIGenCCode(None)
-        self._visited_ret_types = {}
+        self._visited_ret_types: Dict[QAPIGenC, Set[QAPISchemaType]] = {}
 
-    def _begin_user_module(self, name):
+    def _begin_user_module(self, name: str) -> None:
         self._visited_ret_types[self._genc] = set()
         commands = self._module_basename('qapi-commands', name)
         types = self._module_basename('qapi-types', name)
@@ -252,7 +282,7 @@ class QAPISchemaGenCommandVisitor(QAPISchemaModularCVisitor):
 ''',
                              types=types))
 
-    def visit_end(self):
+    def visit_end(self) -> None:
         self._add_system_module('init', ' * QAPI Commands initialization')
         self._genh.add(mcgen('''
 #include "qapi/qmp/dispatch.h"
@@ -268,9 +298,19 @@ void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds);
                                       prefix=self._prefix))
         self._genc.add(gen_registry(self._regy.get_content(), self._prefix))
 
-    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: QAPISourceInfo,
+                      ifcond: List[str],
+                      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:
         if not gen:
             return
         # FIXME: If T is a user-defined type, the user is responsible
@@ -292,7 +332,9 @@ void %(c_prefix)sqmp_init_marshal(QmpCommandList *cmds);
                                                 coroutine))
 
 
-def gen_commands(schema, output_dir, prefix):
+def gen_commands(schema: QAPISchema,
+                 output_dir: str,
+                 prefix: str) -> None:
     vis = QAPISchemaGenCommandVisitor(prefix)
     schema.visit(vis)
     vis.write(output_dir)
diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index ba35abea47..11b86beeab 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -12,12 +12,28 @@
 # See the COPYING file in the top-level directory.
 
 import re
+from typing import Optional, Sequence
 
 
-# ENUMName -> ENUM_NAME, EnumName1 -> ENUM_NAME1
-# ENUM_NAME -> ENUM_NAME, ENUM_NAME1 -> ENUM_NAME1, ENUM_Name2 -> ENUM_NAME2
-# ENUM24_Name -> ENUM24_NAME
-def camel_to_upper(value):
+#: Magic string that gets removed along with all space to its right.
+EATSPACE = '\033EATSPACE.'
+POINTER_SUFFIX = ' *' + EATSPACE
+_C_NAME_TRANS = str.maketrans('.-', '__')
+
+
+def camel_to_upper(value: str) -> str:
+    """
+    Converts CamelCase to CAMEL_CASE.
+
+    Examples::
+
+        ENUMName -> ENUM_NAME
+        EnumName1 -> ENUM_NAME1
+        ENUM_NAME -> ENUM_NAME
+        ENUM_NAME1 -> ENUM_NAME1
+        ENUM_Name2 -> ENUM_NAME2
+        ENUM24_Name -> ENUM24_NAME
+    """
     c_fun_str = c_name(value, False)
     if value.isupper():
         return c_fun_str
@@ -25,36 +41,47 @@ def camel_to_upper(value):
     new_name = ''
     length = len(c_fun_str)
     for i in range(length):
-        c = c_fun_str[i]
-        # When c is upper and no '_' appears before, do more checks
-        if c.isupper() and (i > 0) and c_fun_str[i - 1] != '_':
+        char = c_fun_str[i]
+        # When char is upper case and no '_' appears before, do more checks
+        if char.isupper() and (i > 0) and c_fun_str[i - 1] != '_':
             if i < length - 1 and c_fun_str[i + 1].islower():
                 new_name += '_'
             elif c_fun_str[i - 1].isdigit():
                 new_name += '_'
-        new_name += c
+        new_name += char
     return new_name.lstrip('_').upper()
 
 
-def c_enum_const(type_name, const_name, prefix=None):
+def c_enum_const(type_name: str,
+                 const_name: str,
+                 prefix: Optional[str] = None) -> str:
+    """
+    Generate a C enumeration constant name.
+
+    :param type_name: The name of the enumeration.
+    :param const_name: The name of this constant.
+    :param prefix: Optional, prefix that overrides the type_name.
+    """
     if prefix is not None:
         type_name = prefix
     return camel_to_upper(type_name) + '_' + c_name(const_name, False).upper()
 
 
-c_name_trans = str.maketrans('.-', '__')
+def c_name(name: str, protect: bool = True) -> str:
+    """
+    Map ``name`` to a valid C identifier.
 
+    Used for converting 'name' from a 'name':'type' qapi definition
+    into a generated struct member, as well as converting type names
+    into substrings of a generated C function name.
 
-# Map @name to a valid C identifier.
-# If @protect, avoid returning certain ticklish identifiers (like
-# C keywords) by prepending 'q_'.
-#
-# Used for converting 'name' from a 'name':'type' qapi definition
-# into a generated struct member, as well as converting type names
-# into substrings of a generated C function name.
-# '__a.b_c' -> '__a_b_c', 'x-foo' -> 'x_foo'
-# protect=True: 'int' -> 'q_int'; protect=False: 'int' -> 'int'
-def c_name(name, protect=True):
+    '__a.b_c' -> '__a_b_c', 'x-foo' -> 'x_foo'
+    protect=True: 'int' -> 'q_int'; protect=False: 'int' -> 'int'
+
+    :param name: The name to map.
+    :param protect: If true, avoid returning certain ticklish identifiers
+                    (like C keywords) by prepending ``q_``.
+    """
     # ANSI X3J11/88-090, 3.1.1
     c89_words = set(['auto', 'break', 'case', 'char', 'const', 'continue',
                      'default', 'do', 'double', 'else', 'enum', 'extern',
@@ -82,61 +109,75 @@ def c_name(name, protect=True):
                      'not_eq', 'or', 'or_eq', 'xor', 'xor_eq'])
     # namespace pollution:
     polluted_words = set(['unix', 'errno', 'mips', 'sparc', 'i386'])
-    name = name.translate(c_name_trans)
+    name = name.translate(_C_NAME_TRANS)
     if protect and (name in c89_words | c99_words | c11_words | gcc_words
                     | cpp_words | polluted_words):
         return 'q_' + name
     return name
 
 
-eatspace = '\033EATSPACE.'
-pointer_suffix = ' *' + eatspace
+class Indentation:
+    """
+    Indentation level management.
 
+    :param initial: Initial number of spaces, default 0.
+    """
+    def __init__(self, initial: int = 0) -> None:
+        self._level = initial
 
-def genindent(count):
-    ret = ''
-    for _ in range(count):
-        ret += ' '
-    return ret
+    def __int__(self) -> int:
+        return self._level
+
+    def __repr__(self) -> str:
+        return "{}({:d})".format(type(self).__name__, self._level)
+
+    def __str__(self) -> str:
+        """Return the current indentation as a string of spaces."""
+        return ' ' * self._level
 
+    def __bool__(self) -> bool:
+        """True when there is a non-zero indentation."""
+        return bool(self._level)
 
-indent_level = 0
+    def increase(self, amount: int = 4) -> None:
+        """Increase the indentation level by ``amount``, default 4."""
+        self._level += amount
 
+    def decrease(self, amount: int = 4) -> None:
+        """Decrease the indentation level by ``amount``, default 4."""
+        if self._level < amount:
+            raise ArithmeticError(
+                f"Can't remove {amount:d} spaces from {self!r}")
+        self._level -= amount
 
-def push_indent(indent_amount=4):
-    global indent_level
-    indent_level += indent_amount
 
+#: Global, current indent level for code generation.
+indent = Indentation()
 
-def pop_indent(indent_amount=4):
-    global indent_level
-    indent_level -= indent_amount
 
+def cgen(code: str, **kwds: object) -> str:
+    """
+    Generate ``code`` with ``kwds`` interpolated.
 
-# Generate @code with @kwds interpolated.
-# Obey indent_level, and strip eatspace.
-def cgen(code, **kwds):
+    Obey `indent`, and strip `EATSPACE`.
+    """
     raw = code % kwds
-    if indent_level:
-        indent = genindent(indent_level)
-        # re.subn() lacks flags support before Python 2.7, use re.compile()
-        raw = re.subn(re.compile(r'^(?!(#|$))', re.MULTILINE),
-                      indent, raw)
-        raw = raw[0]
-    return re.sub(re.escape(eatspace) + r' *', '', raw)
+    if indent:
+        raw = re.sub(r'^(?!(#|$))', str(indent), raw, flags=re.MULTILINE)
+    return re.sub(re.escape(EATSPACE) + r' *', '', raw)
 
 
-def mcgen(code, **kwds):
+def mcgen(code: str, **kwds: object) -> str:
     if code[0] == '\n':
         code = code[1:]
     return cgen(code, **kwds)
 
 
-def c_fname(filename):
+def c_fname(filename: str) -> str:
     return re.sub(r'[^A-Za-z0-9_]', '_', filename)
 
 
-def guardstart(name):
+def guardstart(name: str) -> str:
     return mcgen('''
 #ifndef %(name)s
 #define %(name)s
@@ -145,7 +186,7 @@ def guardstart(name):
                  name=c_fname(name).upper())
 
 
-def guardend(name):
+def guardend(name: str) -> str:
     return mcgen('''
 
 #endif /* %(name)s */
@@ -153,7 +194,7 @@ def guardend(name):
                  name=c_fname(name).upper())
 
 
-def gen_if(ifcond):
+def gen_if(ifcond: Sequence[str]) -> str:
     ret = ''
     for ifc in ifcond:
         ret += mcgen('''
@@ -162,31 +203,10 @@ def gen_if(ifcond):
     return ret
 
 
-def gen_endif(ifcond):
+def gen_endif(ifcond: Sequence[str]) -> str:
     ret = ''
     for ifc in reversed(ifcond):
         ret += mcgen('''
 #endif /* %(cond)s */
 ''', cond=ifc)
     return ret
-
-
-def build_params(arg_type, boxed, extra=None):
-    ret = ''
-    sep = ''
-    if boxed:
-        assert arg_type
-        ret += '%s arg' % arg_type.c_param_type()
-        sep = ', '
-    elif arg_type:
-        assert not arg_type.variants
-        for memb in arg_type.members:
-            ret += sep
-            sep = ', '
-            if memb.optional:
-                ret += 'bool has_%s, ' % c_name(memb.name)
-            ret += '%s %s' % (memb.type.c_param_type(),
-                              c_name(memb.name))
-    if extra:
-        ret += sep + extra
-    return ret if ret else 'void'
diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
index b544af5a1c..599f3d1f56 100644
--- a/scripts/qapi/events.py
+++ b/scripts/qapi/events.py
@@ -12,19 +12,31 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from qapi.common import *
-from qapi.gen import QAPISchemaModularCVisitor, ifcontext
-from qapi.schema import QAPISchemaEnumMember
-from qapi.types import gen_enum, gen_enum_lookup
-
-
-def build_event_send_proto(name, arg_type, boxed):
+from typing import List
+
+from .common import c_enum_const, c_name, mcgen
+from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
+from .schema import (
+    QAPISchema,
+    QAPISchemaEnumMember,
+    QAPISchemaFeature,
+    QAPISchemaObjectType,
+)
+from .source import QAPISourceInfo
+from .types import gen_enum, gen_enum_lookup
+
+
+def build_event_send_proto(name: str,
+                           arg_type: QAPISchemaObjectType,
+                           boxed: bool) -> str:
     return 'void qapi_event_send_%(c_name)s(%(param)s)' % {
         'c_name': c_name(name.lower()),
         'param': build_params(arg_type, boxed)}
 
 
-def gen_event_send_decl(name, arg_type, boxed):
+def gen_event_send_decl(name: str,
+                        arg_type: QAPISchemaObjectType,
+                        boxed: bool) -> str:
     return mcgen('''
 
 %(proto)s;
@@ -32,8 +44,12 @@ def gen_event_send_decl(name, arg_type, boxed):
                  proto=build_event_send_proto(name, arg_type, boxed))
 
 
-# Declare and initialize an object 'qapi' using parameters from build_params()
-def gen_param_var(typ):
+def gen_param_var(typ: QAPISchemaObjectType) -> str:
+    """
+    Generate a struct variable holding the event parameters.
+
+    Initialize it with the function arguments defined in `gen_event_send`.
+    """
     assert not typ.variants
     ret = mcgen('''
     %(c_name)s param = {
@@ -61,7 +77,11 @@ def gen_param_var(typ):
     return ret
 
 
-def gen_event_send(name, arg_type, boxed, event_enum_name, event_emit):
+def gen_event_send(name: str,
+                   arg_type: QAPISchemaObjectType,
+                   boxed: bool,
+                   event_enum_name: str,
+                   event_emit: str) -> str:
     # FIXME: Our declaration of local variables (and of 'errp' in the
     # parameter list) can collide with exploded members of the event's
     # data type passed in as parameters.  If this collision ever hits in
@@ -137,15 +157,15 @@ def gen_event_send(name, arg_type, boxed, event_enum_name, event_emit):
 
 class QAPISchemaGenEventVisitor(QAPISchemaModularCVisitor):
 
-    def __init__(self, prefix):
+    def __init__(self, prefix: str):
         super().__init__(
             prefix, 'qapi-events',
             ' * Schema-defined QAPI/QMP events', None, __doc__)
         self._event_enum_name = c_name(prefix + 'QAPIEvent', protect=False)
-        self._event_enum_members = []
+        self._event_enum_members: List[QAPISchemaEnumMember] = []
         self._event_emit_name = c_name(prefix + 'qapi_event_emit')
 
-    def _begin_user_module(self, name):
+    def _begin_user_module(self, name: str) -> None:
         events = self._module_basename('qapi-events', name)
         types = self._module_basename('qapi-types', name)
         visit = self._module_basename('qapi-visit', name)
@@ -168,7 +188,7 @@ class QAPISchemaGenEventVisitor(QAPISchemaModularCVisitor):
 ''',
                              types=types))
 
-    def visit_end(self):
+    def visit_end(self) -> None:
         self._add_system_module('emit', ' * QAPI Events emission')
         self._genc.preamble_add(mcgen('''
 #include "qemu/osdep.h"
@@ -189,7 +209,13 @@ void %(event_emit)s(%(event_enum)s event, QDict *qdict);
                              event_emit=self._event_emit_name,
                              event_enum=self._event_enum_name))
 
-    def visit_event(self, name, info, ifcond, features, arg_type, boxed):
+    def visit_event(self,
+                    name: str,
+                    info: QAPISourceInfo,
+                    ifcond: List[str],
+                    features: List[QAPISchemaFeature],
+                    arg_type: QAPISchemaObjectType,
+                    boxed: bool) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.add(gen_event_send_decl(name, arg_type, boxed))
             self._genc.add(gen_event_send(name, arg_type, boxed,
@@ -200,7 +226,9 @@ void %(event_emit)s(%(event_enum)s event, QDict *qdict);
         self._event_enum_members.append(QAPISchemaEnumMember(name, None))
 
 
-def gen_events(schema, output_dir, prefix):
+def gen_events(schema: QAPISchema,
+               output_dir: str,
+               prefix: str) -> None:
     vis = QAPISchemaGenEventVisitor(prefix)
     schema.visit(vis)
     vis.write(output_dir)
diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
index a15c1fb474..2fcaaa2497 100644
--- a/scripts/qapi/expr.py
+++ b/scripts/qapi/expr.py
@@ -14,10 +14,11 @@
 # This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 
-import re
 from collections import OrderedDict
-from qapi.common import c_name
-from qapi.error import QAPISemError
+import re
+
+from .common import c_name
+from .error import QAPISemError
 
 
 # Names must be letters, numbers, -, and _.  They must start with letter,
diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index ca66c82b5b..b40f18eee3 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -2,7 +2,7 @@
 #
 # QAPI code generation
 #
-# Copyright (c) 2018-2019 Red Hat Inc.
+# Copyright (c) 2015-2019 Red Hat Inc.
 #
 # Authors:
 #  Markus Armbruster <armbru@redhat.com>
@@ -11,39 +11,54 @@
 # This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 
-
-import errno
+from contextlib import contextmanager
 import os
 import re
-from contextlib import contextmanager
-
-from qapi.common import *
-from qapi.schema import QAPISchemaVisitor
+from typing import (
+    Dict,
+    Iterator,
+    List,
+    Optional,
+    Tuple,
+)
+
+from .common import (
+    c_fname,
+    c_name,
+    gen_endif,
+    gen_if,
+    guardend,
+    guardstart,
+    mcgen,
+)
+from .schema import QAPISchemaObjectType, QAPISchemaVisitor
+from .source import QAPISourceInfo
 
 
 class QAPIGen:
-
-    def __init__(self, fname):
+    def __init__(self, fname: Optional[str]):
         self.fname = fname
         self._preamble = ''
         self._body = ''
 
-    def preamble_add(self, text):
+    def preamble_add(self, text: str) -> None:
         self._preamble += text
 
-    def add(self, text):
+    def add(self, text: str) -> None:
         self._body += text
 
-    def get_content(self):
+    def get_content(self) -> str:
         return self._top() + self._preamble + self._body + self._bottom()
 
-    def _top(self):
+    def _top(self) -> str:
+        # pylint: disable=no-self-use
         return ''
 
-    def _bottom(self):
+    def _bottom(self) -> str:
+        # pylint: disable=no-self-use
         return ''
 
-    def write(self, output_dir):
+    def write(self, output_dir: str) -> None:
         # Include paths starting with ../ are used to reuse modules of the main
         # schema in specialised schemas. Don't overwrite the files that are
         # already generated for the main schema.
@@ -51,24 +66,22 @@ class QAPIGen:
             return
         pathname = os.path.join(output_dir, self.fname)
         odir = os.path.dirname(pathname)
+
         if odir:
-            try:
-                os.makedirs(odir)
-            except os.error as e:
-                if e.errno != errno.EEXIST:
-                    raise
+            os.makedirs(odir, exist_ok=True)
+
+        # use os.open for O_CREAT to create and read a non-existant file
         fd = os.open(pathname, os.O_RDWR | os.O_CREAT, 0o666)
-        f = open(fd, 'r+', encoding='utf-8')
-        text = self.get_content()
-        oldtext = f.read(len(text) + 1)
-        if text != oldtext:
-            f.seek(0)
-            f.truncate(0)
-            f.write(text)
-        f.close()
+        with os.fdopen(fd, 'r+', encoding='utf-8') as fp:
+            text = self.get_content()
+            oldtext = fp.read(len(text) + 1)
+            if text != oldtext:
+                fp.seek(0)
+                fp.truncate(0)
+                fp.write(text)
 
 
-def _wrap_ifcond(ifcond, before, after):
+def _wrap_ifcond(ifcond: List[str], before: str, after: str) -> str:
     if before == after:
         return after   # suppress empty #if ... #endif
 
@@ -84,41 +97,62 @@ def _wrap_ifcond(ifcond, before, after):
     return out
 
 
-class QAPIGenCCode(QAPIGen):
+def build_params(arg_type: Optional[QAPISchemaObjectType],
+                 boxed: bool,
+                 extra: Optional[str] = None) -> str:
+    ret = ''
+    sep = ''
+    if boxed:
+        assert arg_type
+        ret += '%s arg' % arg_type.c_param_type()
+        sep = ', '
+    elif arg_type:
+        assert not arg_type.variants
+        for memb in arg_type.members:
+            ret += sep
+            sep = ', '
+            if memb.optional:
+                ret += 'bool has_%s, ' % c_name(memb.name)
+            ret += '%s %s' % (memb.type.c_param_type(),
+                              c_name(memb.name))
+    if extra:
+        ret += sep + extra
+    return ret if ret else 'void'
 
-    def __init__(self, fname):
+
+class QAPIGenCCode(QAPIGen):
+    def __init__(self, fname: Optional[str]):
         super().__init__(fname)
-        self._start_if = None
+        self._start_if: Optional[Tuple[List[str], str, str]] = None
 
-    def start_if(self, ifcond):
+    def start_if(self, ifcond: List[str]) -> None:
         assert self._start_if is None
         self._start_if = (ifcond, self._body, self._preamble)
 
-    def end_if(self):
+    def end_if(self) -> None:
         assert self._start_if
         self._wrap_ifcond()
         self._start_if = None
 
-    def _wrap_ifcond(self):
+    def _wrap_ifcond(self) -> None:
         self._body = _wrap_ifcond(self._start_if[0],
                                   self._start_if[1], self._body)
         self._preamble = _wrap_ifcond(self._start_if[0],
                                       self._start_if[2], self._preamble)
 
-    def get_content(self):
+    def get_content(self) -> str:
         assert self._start_if is None
         return super().get_content()
 
 
 class QAPIGenC(QAPIGenCCode):
-
-    def __init__(self, fname, blurb, pydoc):
+    def __init__(self, fname: str, blurb: str, pydoc: str):
         super().__init__(fname)
         self._blurb = blurb
         self._copyright = '\n * '.join(re.findall(r'^Copyright .*', pydoc,
                                                   re.MULTILINE))
 
-    def _top(self):
+    def _top(self) -> str:
         return mcgen('''
 /* AUTOMATICALLY GENERATED, DO NOT MODIFY */
 
@@ -134,7 +168,7 @@ class QAPIGenC(QAPIGenCCode):
 ''',
                      blurb=self._blurb, copyright=self._copyright)
 
-    def _bottom(self):
+    def _bottom(self) -> str:
         return mcgen('''
 
 /* Dummy declaration to prevent empty .o file */
@@ -144,19 +178,20 @@ char qapi_dummy_%(name)s;
 
 
 class QAPIGenH(QAPIGenC):
-
-    def _top(self):
+    def _top(self) -> str:
         return super()._top() + guardstart(self.fname)
 
-    def _bottom(self):
+    def _bottom(self) -> str:
         return guardend(self.fname)
 
 
 @contextmanager
-def ifcontext(ifcond, *args):
-    """A 'with' statement context manager to wrap with start_if()/end_if()
+def ifcontext(ifcond: List[str], *args: QAPIGenCCode) -> Iterator[None]:
+    """
+    A with-statement context manager that wraps with `start_if()` / `end_if()`.
 
-    *args: any number of QAPIGenCCode
+    :param ifcond: A list of conditionals, passed to `start_if()`.
+    :param args: any number of `QAPIGenCCode`.
 
     Example::
 
@@ -179,8 +214,11 @@ def ifcontext(ifcond, *args):
 
 
 class QAPISchemaMonolithicCVisitor(QAPISchemaVisitor):
-
-    def __init__(self, prefix, what, blurb, pydoc):
+    def __init__(self,
+                 prefix: str,
+                 what: str,
+                 blurb: str,
+                 pydoc: str):
         self._prefix = prefix
         self._what = what
         self._genc = QAPIGenC(self._prefix + self._what + '.c',
@@ -188,38 +226,42 @@ class QAPISchemaMonolithicCVisitor(QAPISchemaVisitor):
         self._genh = QAPIGenH(self._prefix + self._what + '.h',
                               blurb, pydoc)
 
-    def write(self, output_dir):
+    def write(self, output_dir: str) -> None:
         self._genc.write(output_dir)
         self._genh.write(output_dir)
 
 
 class QAPISchemaModularCVisitor(QAPISchemaVisitor):
-
-    def __init__(self, prefix, what, user_blurb, builtin_blurb, pydoc):
+    def __init__(self,
+                 prefix: str,
+                 what: str,
+                 user_blurb: str,
+                 builtin_blurb: Optional[str],
+                 pydoc: str):
         self._prefix = prefix
         self._what = what
         self._user_blurb = user_blurb
         self._builtin_blurb = builtin_blurb
         self._pydoc = pydoc
-        self._genc = None
-        self._genh = None
-        self._module = {}
-        self._main_module = None
+        self._genc: Optional[QAPIGenC] = None
+        self._genh: Optional[QAPIGenH] = None
+        self._module: Dict[Optional[str], Tuple[QAPIGenC, QAPIGenH]] = {}
+        self._main_module: Optional[str] = None
 
     @staticmethod
-    def _is_user_module(name):
-        return name and not name.startswith('./')
+    def _is_user_module(name: Optional[str]) -> bool:
+        return bool(name and not name.startswith('./'))
 
     @staticmethod
-    def _is_builtin_module(name):
+    def _is_builtin_module(name: Optional[str]) -> bool:
         return not name
 
-    def _module_dirname(self, what, name):
+    def _module_dirname(self, name: Optional[str]) -> str:
         if self._is_user_module(name):
             return os.path.dirname(name)
         return ''
 
-    def _module_basename(self, what, name):
+    def _module_basename(self, what: str, name: Optional[str]) -> str:
         ret = '' if self._is_builtin_module(name) else self._prefix
         if self._is_user_module(name):
             basename = os.path.basename(name)
@@ -231,27 +273,27 @@ class QAPISchemaModularCVisitor(QAPISchemaVisitor):
             ret += re.sub(r'-', '-' + name + '-', what)
         return ret
 
-    def _module_filename(self, what, name):
-        return os.path.join(self._module_dirname(what, name),
+    def _module_filename(self, what: str, name: Optional[str]) -> str:
+        return os.path.join(self._module_dirname(name),
                             self._module_basename(what, name))
 
-    def _add_module(self, name, blurb):
+    def _add_module(self, name: Optional[str], blurb: str) -> None:
         basename = self._module_filename(self._what, name)
         genc = QAPIGenC(basename + '.c', blurb, self._pydoc)
         genh = QAPIGenH(basename + '.h', blurb, self._pydoc)
         self._module[name] = (genc, genh)
         self._genc, self._genh = self._module[name]
 
-    def _add_user_module(self, name, blurb):
+    def _add_user_module(self, name: str, blurb: str) -> None:
         assert self._is_user_module(name)
         if self._main_module is None:
             self._main_module = name
         self._add_module(name, blurb)
 
-    def _add_system_module(self, name, blurb):
+    def _add_system_module(self, name: Optional[str], blurb: str) -> None:
         self._add_module(name and './' + name, blurb)
 
-    def write(self, output_dir, opt_builtins=False):
+    def write(self, output_dir: str, opt_builtins: bool = False) -> None:
         for name in self._module:
             if self._is_builtin_module(name) and not opt_builtins:
                 continue
@@ -259,13 +301,13 @@ class QAPISchemaModularCVisitor(QAPISchemaVisitor):
             genc.write(output_dir)
             genh.write(output_dir)
 
-    def _begin_system_module(self, name):
+    def _begin_system_module(self, name: None) -> None:
         pass
 
-    def _begin_user_module(self, name):
+    def _begin_user_module(self, name: str) -> None:
         pass
 
-    def visit_module(self, name):
+    def visit_module(self, name: Optional[str]) -> None:
         if name is None:
             if self._builtin_blurb:
                 self._add_system_module(None, self._builtin_blurb)
@@ -279,7 +321,7 @@ class QAPISchemaModularCVisitor(QAPISchemaVisitor):
             self._add_user_module(name, self._user_blurb)
             self._begin_user_module(name)
 
-    def visit_include(self, name, info):
+    def visit_include(self, name: str, info: QAPISourceInfo) -> None:
         relname = os.path.relpath(self._module_filename(self._what, name),
                                   os.path.dirname(self._genh.fname))
         self._genh.preamble_add(mcgen('''
diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
index 5907b09cd5..fafec94e02 100644
--- a/scripts/qapi/introspect.py
+++ b/scripts/qapi/introspect.py
@@ -10,10 +10,18 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from qapi.common import *
-from qapi.gen import QAPISchemaMonolithicCVisitor
-from qapi.schema import (QAPISchemaArrayType, QAPISchemaBuiltinType,
-                         QAPISchemaType)
+from .common import (
+    c_name,
+    gen_endif,
+    gen_if,
+    mcgen,
+)
+from .gen import QAPISchemaMonolithicCVisitor
+from .schema import (
+    QAPISchemaArrayType,
+    QAPISchemaBuiltinType,
+    QAPISchemaType,
+)
 
 
 def _make_tree(obj, ifcond, features, extra=None):
diff --git a/scripts/qapi/main.py b/scripts/qapi/main.py
new file mode 100644
index 0000000000..42517210b8
--- /dev/null
+++ b/scripts/qapi/main.py
@@ -0,0 +1,95 @@
+# This work is licensed under the terms of the GNU GPL, version 2 or later.
+# See the COPYING file in the top-level directory.
+
+"""
+QAPI Generator
+
+This is the main entry point for generating C code from the QAPI schema.
+"""
+
+import argparse
+import re
+import sys
+from typing import Optional
+
+from .commands import gen_commands
+from .error import QAPIError
+from .events import gen_events
+from .introspect import gen_introspect
+from .schema import QAPISchema
+from .types import gen_types
+from .visit import gen_visit
+
+
+def invalid_prefix_char(prefix: str) -> Optional[str]:
+    match = re.match(r'([A-Za-z_.-][A-Za-z0-9_.-]*)?', prefix)
+    if match.end() != len(prefix):
+        return prefix[match.end()]
+    return None
+
+
+def generate(schema_file: str,
+             output_dir: str,
+             prefix: str,
+             unmask: bool = False,
+             builtins: bool = False) -> None:
+    """
+    Generate C code for the given schema into the target directory.
+
+    :param schema_file: The primary QAPI schema file.
+    :param output_dir: The output directory to store generated code.
+    :param prefix: Optional C-code prefix for symbol names.
+    :param unmask: Expose non-ABI names through introspection?
+    :param builtins: Generate code for built-in types?
+
+    :raise QAPIError: On failures.
+    """
+    assert invalid_prefix_char(prefix) is None
+
+    schema = QAPISchema(schema_file)
+    gen_types(schema, output_dir, prefix, builtins)
+    gen_visit(schema, output_dir, prefix, builtins)
+    gen_commands(schema, output_dir, prefix)
+    gen_events(schema, output_dir, prefix)
+    gen_introspect(schema, output_dir, prefix, unmask)
+
+
+def main() -> int:
+    """
+    gapi-gen executable entry point.
+    Expects arguments via sys.argv, see --help for details.
+
+    :return: int, 0 on success, 1 on failure.
+    """
+    parser = argparse.ArgumentParser(
+        description='Generate code from a QAPI schema')
+    parser.add_argument('-b', '--builtins', action='store_true',
+                        help="generate code for built-in types")
+    parser.add_argument('-o', '--output-dir', action='store',
+                        default='',
+                        help="write output to directory OUTPUT_DIR")
+    parser.add_argument('-p', '--prefix', action='store',
+                        default='',
+                        help="prefix for symbols")
+    parser.add_argument('-u', '--unmask-non-abi-names', action='store_true',
+                        dest='unmask',
+                        help="expose non-ABI names in introspection")
+    parser.add_argument('schema', action='store')
+    args = parser.parse_args()
+
+    funny_char = invalid_prefix_char(args.prefix)
+    if funny_char:
+        msg = f"funny character '{funny_char}' in argument of --prefix"
+        print(f"{sys.argv[0]}: {msg}", file=sys.stderr)
+        return 1
+
+    try:
+        generate(args.schema,
+                 output_dir=args.output_dir,
+                 prefix=args.prefix,
+                 unmask=args.unmask,
+                 builtins=args.builtins)
+    except QAPIError as err:
+        print(f"{sys.argv[0]}: {str(err)}", file=sys.stderr)
+        return 1
+    return 0
diff --git a/scripts/qapi/mypy.ini b/scripts/qapi/mypy.ini
new file mode 100644
index 0000000000..74fc6c8215
--- /dev/null
+++ b/scripts/qapi/mypy.ini
@@ -0,0 +1,30 @@
+[mypy]
+strict = True
+strict_optional = False
+disallow_untyped_calls = False
+python_version = 3.6
+
+[mypy-qapi.error]
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+check_untyped_defs = False
+
+[mypy-qapi.expr]
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+check_untyped_defs = False
+
+[mypy-qapi.introspect]
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+check_untyped_defs = False
+
+[mypy-qapi.parser]
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+check_untyped_defs = False
+
+[mypy-qapi.schema]
+disallow_untyped_defs = False
+disallow_incomplete_defs = False
+check_untyped_defs = False
diff --git a/scripts/qapi/parser.py b/scripts/qapi/parser.py
index 9d1a3e2eea..e7b9d670ad 100644
--- a/scripts/qapi/parser.py
+++ b/scripts/qapi/parser.py
@@ -14,12 +14,12 @@
 # This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 
+from collections import OrderedDict
 import os
 import re
-from collections import OrderedDict
 
-from qapi.error import QAPIParseError, QAPISemError
-from qapi.source import QAPISourceInfo
+from .error import QAPIParseError, QAPISemError
+from .source import QAPISourceInfo
 
 
 class QAPISchemaParser:
diff --git a/scripts/qapi/pylintrc b/scripts/qapi/pylintrc
new file mode 100644
index 0000000000..b9e077a164
--- /dev/null
+++ b/scripts/qapi/pylintrc
@@ -0,0 +1,70 @@
+[MASTER]
+
+# Add files or directories matching the regex patterns to the ignore list.
+# The regex matches against base names, not paths.
+ignore-patterns=error.py,
+                expr.py,
+                parser.py,
+                schema.py,
+
+
+[MESSAGES CONTROL]
+
+# Disable the message, report, category or checker with the given id(s). You
+# can either give multiple identifiers separated by comma (,) or put this
+# option multiple times (only on the command line, not in the configuration
+# file where it should appear only once). You can also use "--disable=all" to
+# disable everything first and then reenable specific checks. For example, if
+# you want to run only the similarities checker, you can use "--disable=all
+# --enable=similarities". If you want to run only the classes checker, but have
+# no Warning level messages displayed, use "--disable=all --enable=classes
+# --disable=W".
+disable=fixme,
+        missing-docstring,
+        too-many-arguments,
+        too-many-branches,
+        too-many-statements,
+        too-many-instance-attributes,
+
+[REPORTS]
+
+[REFACTORING]
+
+[MISCELLANEOUS]
+
+[LOGGING]
+
+[BASIC]
+
+# Good variable names which should always be accepted, separated by a comma.
+good-names=i,
+           j,
+           k,
+           ex,
+           Run,
+           _,
+           fp,  # fp = open(...)
+           fd,  # fd = os.open(...)
+
+[VARIABLES]
+
+[STRING]
+
+[SPELLING]
+
+[FORMAT]
+
+[SIMILARITIES]
+
+# Ignore import statements themselves when computing similarities.
+ignore-imports=yes
+
+[TYPECHECK]
+
+[CLASSES]
+
+[IMPORTS]
+
+[DESIGN]
+
+[EXCEPTIONS]
diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
index d1307ec661..720449feee 100644
--- a/scripts/qapi/schema.py
+++ b/scripts/qapi/schema.py
@@ -14,18 +14,19 @@
 
 # TODO catching name collisions in generated code would be nice
 
+from collections import OrderedDict
 import os
 import re
-from collections import OrderedDict
+from typing import Optional
 
-from qapi.common import c_name, pointer_suffix
-from qapi.error import QAPIError, QAPISemError
-from qapi.expr import check_exprs
-from qapi.parser import QAPISchemaParser
+from .common import POINTER_SUFFIX, c_name
+from .error import QAPIError, QAPISemError
+from .expr import check_exprs
+from .parser import QAPISchemaParser
 
 
 class QAPISchemaEntity:
-    meta = None
+    meta: Optional[str] = None
 
     def __init__(self, name, info, doc, ifcond=None, features=None):
         assert name is None or isinstance(name, str)
@@ -309,7 +310,7 @@ class QAPISchemaArrayType(QAPISchemaType):
         return True
 
     def c_type(self):
-        return c_name(self.name) + pointer_suffix
+        return c_name(self.name) + POINTER_SUFFIX
 
     def json_type(self):
         return 'array'
@@ -430,7 +431,7 @@ class QAPISchemaObjectType(QAPISchemaType):
 
     def c_type(self):
         assert not self.is_implicit()
-        return c_name(self.name) + pointer_suffix
+        return c_name(self.name) + POINTER_SUFFIX
 
     def c_unboxed_type(self):
         return c_name(self.name)
@@ -504,7 +505,7 @@ class QAPISchemaAlternateType(QAPISchemaType):
             v.connect_doc(doc)
 
     def c_type(self):
-        return c_name(self.name) + pointer_suffix
+        return c_name(self.name) + POINTER_SUFFIX
 
     def json_type(self):
         return 'value'
@@ -536,7 +537,7 @@ class QAPISchemaVariants:
             v.set_defined_in(name)
 
     def check(self, schema, seen):
-        if not self.tag_member: # flat union
+        if not self.tag_member:  # flat union
             self.tag_member = seen.get(c_name(self._tag_name))
             base = "'base'"
             # Pointing to the base type when not implicit would be
@@ -824,7 +825,7 @@ class QAPISchema:
         self._entity_dict = {}
         self._module_dict = OrderedDict()
         self._schema_dir = os.path.dirname(fname)
-        self._make_module(None) # built-ins
+        self._make_module(None)  # built-ins
         self._make_module(fname)
         self._predefining = True
         self._def_predefineds()
@@ -899,7 +900,7 @@ class QAPISchema:
         self._make_array_type(name, None)
 
     def _def_predefineds(self):
-        for t in [('str',    'string',  'char' + pointer_suffix),
+        for t in [('str',    'string',  'char' + POINTER_SUFFIX),
                   ('number', 'number',  'double'),
                   ('int',    'int',     'int64_t'),
                   ('int8',   'int',     'int8_t'),
@@ -912,8 +913,8 @@ class QAPISchema:
                   ('uint64', 'int',     'uint64_t'),
                   ('size',   'int',     'uint64_t'),
                   ('bool',   'boolean', 'bool'),
-                  ('any',    'value',   'QObject' + pointer_suffix),
-                  ('null',   'null',    'QNull' + pointer_suffix)]:
+                  ('any',    'value',   'QObject' + POINTER_SUFFIX),
+                  ('null',   'null',    'QNull' + POINTER_SUFFIX)]:
             self._def_builtin_type(*t)
         self.the_empty_object_type = QAPISchemaObjectType(
             'q_empty', None, None, None, None, None, [], None)
@@ -968,7 +969,9 @@ class QAPISchema:
             # But it's not tight: the disjunction need not imply it.  We
             # may end up compiling useless wrapper types.
             # TODO kill simple unions or implement the disjunction
-            assert (ifcond or []) == typ._ifcond # pylint: disable=protected-access
+
+            # pylint: disable=protected-access
+            assert (ifcond or []) == typ._ifcond
         else:
             self._def_entity(QAPISchemaObjectType(
                 name, info, None, ifcond, None, None, members, None))
diff --git a/scripts/qapi/source.py b/scripts/qapi/source.py
index e97b9a8e15..d7a79a9b8a 100644
--- a/scripts/qapi/source.py
+++ b/scripts/qapi/source.py
@@ -11,37 +11,46 @@
 
 import copy
 import sys
+from typing import List, Optional, TypeVar
 
 
 class QAPISchemaPragma:
-    def __init__(self):
+    # Replace with @dataclass in Python 3.7+
+    # pylint: disable=too-few-public-methods
+
+    def __init__(self) -> None:
         # Are documentation comments required?
         self.doc_required = False
         # Whitelist of commands allowed to return a non-dictionary
-        self.returns_whitelist = []
+        self.returns_whitelist: List[str] = []
         # Whitelist of entities allowed to violate case conventions
-        self.name_case_whitelist = []
+        self.name_case_whitelist: List[str] = []
 
 
 class QAPISourceInfo:
-    def __init__(self, fname, line, parent):
+    T = TypeVar('T', bound='QAPISourceInfo')
+
+    def __init__(self, fname: str, line: int,
+                 parent: Optional['QAPISourceInfo']):
         self.fname = fname
         self.line = line
         self.parent = parent
-        self.pragma = parent.pragma if parent else QAPISchemaPragma()
-        self.defn_meta = None
-        self.defn_name = None
+        self.pragma: QAPISchemaPragma = (
+            parent.pragma if parent else QAPISchemaPragma()
+        )
+        self.defn_meta: Optional[str] = None
+        self.defn_name: Optional[str] = None
 
-    def set_defn(self, meta, name):
+    def set_defn(self, meta: str, name: str) -> None:
         self.defn_meta = meta
         self.defn_name = name
 
-    def next_line(self):
+    def next_line(self: T) -> T:
         info = copy.copy(self)
         info.line += 1
         return info
 
-    def loc(self):
+    def loc(self) -> str:
         if self.fname is None:
             return sys.argv[0]
         ret = self.fname
@@ -49,13 +58,13 @@ class QAPISourceInfo:
             ret += ':%d' % self.line
         return ret
 
-    def in_defn(self):
+    def in_defn(self) -> str:
         if self.defn_name:
             return "%s: In %s '%s':\n" % (self.fname,
                                           self.defn_meta, self.defn_name)
         return ''
 
-    def include_path(self):
+    def include_path(self) -> str:
         ret = ''
         parent = self.parent
         while parent:
@@ -63,5 +72,5 @@ class QAPISourceInfo:
             parent = parent.parent
         return ret
 
-    def __str__(self):
+    def __str__(self) -> str:
         return self.include_path() + self.in_defn() + self.loc()
diff --git a/scripts/qapi/types.py b/scripts/qapi/types.py
index 3640f17cd6..2b4916cdaa 100644
--- a/scripts/qapi/types.py
+++ b/scripts/qapi/types.py
@@ -13,9 +13,26 @@ This work is licensed under the terms of the GNU GPL, version 2.
 # See the COPYING file in the top-level directory.
 """
 
-from qapi.common import *
-from qapi.gen import QAPISchemaModularCVisitor, ifcontext
-from qapi.schema import QAPISchemaEnumMember, QAPISchemaObjectType
+from typing import List, Optional
+
+from .common import (
+    c_enum_const,
+    c_name,
+    gen_endif,
+    gen_if,
+    mcgen,
+)
+from .gen import QAPISchemaModularCVisitor, ifcontext
+from .schema import (
+    QAPISchema,
+    QAPISchemaEnumMember,
+    QAPISchemaFeature,
+    QAPISchemaObjectType,
+    QAPISchemaObjectTypeMember,
+    QAPISchemaType,
+    QAPISchemaVariants,
+)
+from .source import QAPISourceInfo
 
 
 # variants must be emitted before their container; track what has already
@@ -23,21 +40,23 @@ from qapi.schema import QAPISchemaEnumMember, QAPISchemaObjectType
 objects_seen = set()
 
 
-def gen_enum_lookup(name, members, prefix=None):
+def gen_enum_lookup(name: str,
+                    members: List[QAPISchemaEnumMember],
+                    prefix: Optional[str] = None) -> str:
     ret = mcgen('''
 
 const QEnumLookup %(c_name)s_lookup = {
     .array = (const char *const[]) {
 ''',
                 c_name=c_name(name))
-    for m in members:
-        ret += gen_if(m.ifcond)
-        index = c_enum_const(name, m.name, prefix)
+    for memb in members:
+        ret += gen_if(memb.ifcond)
+        index = c_enum_const(name, memb.name, prefix)
         ret += mcgen('''
         [%(index)s] = "%(name)s",
 ''',
-                     index=index, name=m.name)
-        ret += gen_endif(m.ifcond)
+                     index=index, name=memb.name)
+        ret += gen_endif(memb.ifcond)
 
     ret += mcgen('''
     },
@@ -48,7 +67,9 @@ const QEnumLookup %(c_name)s_lookup = {
     return ret
 
 
-def gen_enum(name, members, prefix=None):
+def gen_enum(name: str,
+             members: List[QAPISchemaEnumMember],
+             prefix: Optional[str] = None) -> str:
     # append automatically generated _MAX value
     enum_members = members + [QAPISchemaEnumMember('_MAX', None)]
 
@@ -58,13 +79,13 @@ typedef enum %(c_name)s {
 ''',
                 c_name=c_name(name))
 
-    for m in enum_members:
-        ret += gen_if(m.ifcond)
+    for memb in enum_members:
+        ret += gen_if(memb.ifcond)
         ret += mcgen('''
     %(c_enum)s,
 ''',
-                     c_enum=c_enum_const(name, m.name, prefix))
-        ret += gen_endif(m.ifcond)
+                     c_enum=c_enum_const(name, memb.name, prefix))
+        ret += gen_endif(memb.ifcond)
 
     ret += mcgen('''
 } %(c_name)s;
@@ -82,7 +103,7 @@ extern const QEnumLookup %(c_name)s_lookup;
     return ret
 
 
-def gen_fwd_object_or_array(name):
+def gen_fwd_object_or_array(name: str) -> str:
     return mcgen('''
 
 typedef struct %(c_name)s %(c_name)s;
@@ -90,7 +111,7 @@ typedef struct %(c_name)s %(c_name)s;
                  c_name=c_name(name))
 
 
-def gen_array(name, element_type):
+def gen_array(name: str, element_type: QAPISchemaType) -> str:
     return mcgen('''
 
 struct %(c_name)s {
@@ -101,7 +122,7 @@ struct %(c_name)s {
                  c_name=c_name(name), c_type=element_type.c_type())
 
 
-def gen_struct_members(members):
+def gen_struct_members(members: List[QAPISchemaObjectTypeMember]) -> str:
     ret = ''
     for memb in members:
         ret += gen_if(memb.ifcond)
@@ -118,17 +139,21 @@ def gen_struct_members(members):
     return ret
 
 
-def gen_object(name, ifcond, base, members, variants):
+def gen_object(name: str, ifcond: List[str],
+               base: Optional[QAPISchemaObjectType],
+               members: List[QAPISchemaObjectTypeMember],
+               variants: Optional[QAPISchemaVariants]) -> str:
     if name in objects_seen:
         return ''
     objects_seen.add(name)
 
     ret = ''
-    if variants:
-        for v in variants.variants:
-            if isinstance(v.type, QAPISchemaObjectType):
-                ret += gen_object(v.type.name, v.type.ifcond, v.type.base,
-                                  v.type.local_members, v.type.variants)
+    for var in variants.variants if variants else ():
+        obj = var.type
+        if not isinstance(obj, QAPISchemaObjectType):
+            continue
+        ret += gen_object(obj.name, obj.ifcond, obj.base,
+                          obj.local_members, obj.variants)
 
     ret += mcgen('''
 
@@ -172,7 +197,7 @@ struct %(c_name)s {
     return ret
 
 
-def gen_upcast(name, base):
+def gen_upcast(name: str, base: QAPISchemaObjectType) -> str:
     # C makes const-correctness ugly.  We have to cast away const to let
     # this function work for both const and non-const obj.
     return mcgen('''
@@ -185,7 +210,7 @@ static inline %(base)s *qapi_%(c_name)s_base(const %(c_name)s *obj)
                  c_name=c_name(name), base=base.c_name())
 
 
-def gen_variants(variants):
+def gen_variants(variants: QAPISchemaVariants) -> str:
     ret = mcgen('''
     union { /* union tag is @%(c_name)s */
 ''',
@@ -209,7 +234,7 @@ def gen_variants(variants):
     return ret
 
 
-def gen_type_cleanup_decl(name):
+def gen_type_cleanup_decl(name: str) -> str:
     ret = mcgen('''
 
 void qapi_free_%(c_name)s(%(c_name)s *obj);
@@ -219,7 +244,7 @@ G_DEFINE_AUTOPTR_CLEANUP_FUNC(%(c_name)s, qapi_free_%(c_name)s)
     return ret
 
 
-def gen_type_cleanup(name):
+def gen_type_cleanup(name: str) -> str:
     ret = mcgen('''
 
 void qapi_free_%(c_name)s(%(c_name)s *obj)
@@ -241,12 +266,12 @@ void qapi_free_%(c_name)s(%(c_name)s *obj)
 
 class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
 
-    def __init__(self, prefix):
+    def __init__(self, prefix: str):
         super().__init__(
             prefix, 'qapi-types', ' * Schema-defined QAPI types',
             ' * Built-in QAPI types', __doc__)
 
-    def _begin_system_module(self, name):
+    def _begin_system_module(self, name: None) -> None:
         self._genc.preamble_add(mcgen('''
 #include "qemu/osdep.h"
 #include "qapi/dealloc-visitor.h"
@@ -257,7 +282,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
 #include "qapi/util.h"
 '''))
 
-    def _begin_user_module(self, name):
+    def _begin_user_module(self, name: str) -> None:
         types = self._module_basename('qapi-types', name)
         visit = self._module_basename('qapi-visit', name)
         self._genc.preamble_add(mcgen('''
@@ -271,27 +296,43 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
 #include "qapi/qapi-builtin-types.h"
 '''))
 
-    def visit_begin(self, schema):
+    def visit_begin(self, schema: QAPISchema) -> None:
         # gen_object() is recursive, ensure it doesn't visit the empty type
         objects_seen.add(schema.the_empty_object_type.name)
 
-    def _gen_type_cleanup(self, name):
+    def _gen_type_cleanup(self, name: str) -> None:
         self._genh.add(gen_type_cleanup_decl(name))
         self._genc.add(gen_type_cleanup(name))
 
-    def visit_enum_type(self, name, info, ifcond, features, members, prefix):
+    def visit_enum_type(self,
+                        name: str,
+                        info: Optional[QAPISourceInfo],
+                        ifcond: List[str],
+                        features: List[QAPISchemaFeature],
+                        members: List[QAPISchemaEnumMember],
+                        prefix: Optional[str]) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.preamble_add(gen_enum(name, members, prefix))
             self._genc.add(gen_enum_lookup(name, members, prefix))
 
-    def visit_array_type(self, name, info, ifcond, element_type):
+    def visit_array_type(self,
+                         name: str,
+                         info: Optional[QAPISourceInfo],
+                         ifcond: List[str],
+                         element_type: QAPISchemaType) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.preamble_add(gen_fwd_object_or_array(name))
             self._genh.add(gen_array(name, element_type))
             self._gen_type_cleanup(name)
 
-    def visit_object_type(self, name, info, ifcond, features,
-                          base, members, variants):
+    def visit_object_type(self,
+                          name: str,
+                          info: Optional[QAPISourceInfo],
+                          ifcond: List[str],
+                          features: List[QAPISchemaFeature],
+                          base: Optional[QAPISchemaObjectType],
+                          members: List[QAPISchemaObjectTypeMember],
+                          variants: Optional[QAPISchemaVariants]) -> None:
         # Nothing to do for the special empty builtin
         if name == 'q_empty':
             return
@@ -307,7 +348,12 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
                 # implicit types won't be directly allocated/freed
                 self._gen_type_cleanup(name)
 
-    def visit_alternate_type(self, name, info, ifcond, features, variants):
+    def visit_alternate_type(self,
+                             name: str,
+                             info: QAPISourceInfo,
+                             ifcond: List[str],
+                             features: List[QAPISchemaFeature],
+                             variants: QAPISchemaVariants) -> None:
         with ifcontext(ifcond, self._genh):
             self._genh.preamble_add(gen_fwd_object_or_array(name))
         self._genh.add(gen_object(name, ifcond, None,
@@ -316,7 +362,10 @@ class QAPISchemaGenTypeVisitor(QAPISchemaModularCVisitor):
             self._gen_type_cleanup(name)
 
 
-def gen_types(schema, output_dir, prefix, opt_builtins):
+def gen_types(schema: QAPISchema,
+              output_dir: str,
+              prefix: str,
+              opt_builtins: bool) -> None:
     vis = QAPISchemaGenTypeVisitor(prefix)
     schema.visit(vis)
     vis.write(output_dir, opt_builtins)
diff --git a/scripts/qapi/visit.py b/scripts/qapi/visit.py
index cdabc5fa28..339f152152 100644
--- a/scripts/qapi/visit.py
+++ b/scripts/qapi/visit.py
@@ -13,22 +13,43 @@ This work is licensed under the terms of the GNU GPL, version 2.
 See the COPYING file in the top-level directory.
 """
 
-from qapi.common import *
-from qapi.gen import QAPISchemaModularCVisitor, ifcontext
-from qapi.schema import QAPISchemaObjectType
-
-
-def gen_visit_decl(name, scalar=False):
+from typing import List, Optional
+
+from .common import (
+    c_enum_const,
+    c_name,
+    gen_endif,
+    gen_if,
+    indent,
+    mcgen,
+)
+from .gen import QAPISchemaModularCVisitor, ifcontext
+from .schema import (
+    QAPISchema,
+    QAPISchemaEnumMember,
+    QAPISchemaEnumType,
+    QAPISchemaFeature,
+    QAPISchemaObjectType,
+    QAPISchemaObjectTypeMember,
+    QAPISchemaType,
+    QAPISchemaVariants,
+)
+from .source import QAPISourceInfo
+
+
+def gen_visit_decl(name: str, scalar: bool = False) -> str:
     c_type = c_name(name) + ' *'
     if not scalar:
         c_type += '*'
     return mcgen('''
-bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error **errp);
+
+bool visit_type_%(c_name)s(Visitor *v, const char *name,
+                 %(c_type)sobj, Error **errp);
 ''',
                  c_name=c_name(name), c_type=c_type)
 
 
-def gen_visit_members_decl(name):
+def gen_visit_members_decl(name: str) -> str:
     return mcgen('''
 
 bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp);
@@ -36,7 +57,10 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp);
                  c_name=c_name(name))
 
 
-def gen_visit_object_members(name, base, members, variants):
+def gen_visit_object_members(name: str,
+                             base: Optional[QAPISchemaObjectType],
+                             members: List[QAPISchemaObjectTypeMember],
+                             variants: Optional[QAPISchemaVariants]) -> str:
     ret = mcgen('''
 
 bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
@@ -59,7 +83,7 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
     if (visit_optional(v, "%(name)s", &obj->has_%(c_name)s)) {
 ''',
                          name=memb.name, c_name=c_name(memb.name))
-            push_indent()
+            indent.increase()
         ret += mcgen('''
     if (!visit_type_%(c_type)s(v, "%(name)s", &obj->%(c_name)s, errp)) {
         return false;
@@ -68,22 +92,24 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
                      c_type=memb.type.c_name(), name=memb.name,
                      c_name=c_name(memb.name))
         if memb.optional:
-            pop_indent()
+            indent.decrease()
             ret += mcgen('''
     }
 ''')
         ret += gen_endif(memb.ifcond)
 
     if variants:
+        tag_member = variants.tag_member
+        assert isinstance(tag_member.type, QAPISchemaEnumType)
+
         ret += mcgen('''
     switch (obj->%(c_name)s) {
 ''',
-                     c_name=c_name(variants.tag_member.name))
+                     c_name=c_name(tag_member.name))
 
         for var in variants.variants:
-            case_str = c_enum_const(variants.tag_member.type.name,
-                                    var.name,
-                                    variants.tag_member.type.prefix)
+            case_str = c_enum_const(tag_member.type.name, var.name,
+                                    tag_member.type.prefix)
             ret += gen_if(var.ifcond)
             if var.type.name == 'q_empty':
                 # valid variant and nothing to do
@@ -114,10 +140,11 @@ bool visit_type_%(c_name)s_members(Visitor *v, %(c_name)s *obj, Error **errp)
     return ret
 
 
-def gen_visit_list(name, element_type):
+def gen_visit_list(name: str, element_type: QAPISchemaType) -> str:
     return mcgen('''
 
-bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
+bool visit_type_%(c_name)s(Visitor *v, const char *name,
+                 %(c_name)s **obj, Error **errp)
 {
     bool ok = false;
     %(c_name)s *tail;
@@ -147,10 +174,11 @@ out_obj:
                  c_name=c_name(name), c_elt_type=element_type.c_name())
 
 
-def gen_visit_enum(name):
+def gen_visit_enum(name: str) -> str:
     return mcgen('''
 
-bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s *obj, Error **errp)
+bool visit_type_%(c_name)s(Visitor *v, const char *name,
+                 %(c_name)s *obj, Error **errp)
 {
     int value = *obj;
     bool ok = visit_type_enum(v, name, &value, &%(c_name)s_lookup, errp);
@@ -161,10 +189,11 @@ bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s *obj, Error
                  c_name=c_name(name))
 
 
-def gen_visit_alternate(name, variants):
+def gen_visit_alternate(name: str, variants: QAPISchemaVariants) -> str:
     ret = mcgen('''
 
-bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
+bool visit_type_%(c_name)s(Visitor *v, const char *name,
+                 %(c_name)s **obj, Error **errp)
 {
     bool ok = false;
 
@@ -236,10 +265,11 @@ out_obj:
     return ret
 
 
-def gen_visit_object(name, base, members, variants):
+def gen_visit_object(name: str) -> str:
     return mcgen('''
 
-bool visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
+bool visit_type_%(c_name)s(Visitor *v, const char *name,
+                 %(c_name)s **obj, Error **errp)
 {
     bool ok = false;
 
@@ -270,12 +300,12 @@ out_obj:
 
 class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
 
-    def __init__(self, prefix):
+    def __init__(self, prefix: str):
         super().__init__(
             prefix, 'qapi-visit', ' * Schema-defined QAPI visitors',
             ' * Built-in QAPI visitors', __doc__)
 
-    def _begin_system_module(self, name):
+    def _begin_system_module(self, name: None) -> None:
         self._genc.preamble_add(mcgen('''
 #include "qemu/osdep.h"
 #include "qapi/error.h"
@@ -287,7 +317,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
 
 '''))
 
-    def _begin_user_module(self, name):
+    def _begin_user_module(self, name: str) -> None:
         types = self._module_basename('qapi-types', name)
         visit = self._module_basename('qapi-visit', name)
         self._genc.preamble_add(mcgen('''
@@ -304,18 +334,34 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
 ''',
                                       types=types))
 
-    def visit_enum_type(self, name, info, ifcond, features, members, prefix):
+    def visit_enum_type(self,
+                        name: str,
+                        info: QAPISourceInfo,
+                        ifcond: List[str],
+                        features: List[QAPISchemaFeature],
+                        members: List[QAPISchemaEnumMember],
+                        prefix: Optional[str]) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.add(gen_visit_decl(name, scalar=True))
             self._genc.add(gen_visit_enum(name))
 
-    def visit_array_type(self, name, info, ifcond, element_type):
+    def visit_array_type(self,
+                         name: str,
+                         info: Optional[QAPISourceInfo],
+                         ifcond: List[str],
+                         element_type: QAPISchemaType) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.add(gen_visit_decl(name))
             self._genc.add(gen_visit_list(name, element_type))
 
-    def visit_object_type(self, name, info, ifcond, features,
-                          base, members, variants):
+    def visit_object_type(self,
+                          name: str,
+                          info: Optional[QAPISourceInfo],
+                          ifcond: List[str],
+                          features: List[QAPISchemaFeature],
+                          base: Optional[QAPISchemaObjectType],
+                          members: List[QAPISchemaObjectTypeMember],
+                          variants: Optional[QAPISchemaVariants]) -> None:
         # Nothing to do for the special empty builtin
         if name == 'q_empty':
             return
@@ -328,15 +374,23 @@ class QAPISchemaGenVisitVisitor(QAPISchemaModularCVisitor):
             if not name.startswith('q_'):
                 # only explicit types need an allocating visit
                 self._genh.add(gen_visit_decl(name))
-                self._genc.add(gen_visit_object(name, base, members, variants))
-
-    def visit_alternate_type(self, name, info, ifcond, features, variants):
+                self._genc.add(gen_visit_object(name))
+
+    def visit_alternate_type(self,
+                             name: str,
+                             info: QAPISourceInfo,
+                             ifcond: List[str],
+                             features: List[QAPISchemaFeature],
+                             variants: QAPISchemaVariants) -> None:
         with ifcontext(ifcond, self._genh, self._genc):
             self._genh.add(gen_visit_decl(name))
             self._genc.add(gen_visit_alternate(name, variants))
 
 
-def gen_visit(schema, output_dir, prefix, opt_builtins):
+def gen_visit(schema: QAPISchema,
+              output_dir: str,
+              prefix: str,
+              opt_builtins: bool) -> None:
     vis = QAPISchemaGenVisitVisitor(prefix)
     schema.visit(vis)
     vis.write(output_dir, opt_builtins)