diff mbox series

[v5,17/36] qapi/common.py: move build_params into gen.py

Message ID 20201005195158.2348217-18-jsnow@redhat.com
State New, archived
Headers show
Series qapi: static typing conversion, pt1 | expand

Commit Message

John Snow Oct. 5, 2020, 7:51 p.m. UTC
Including it in common.py creates a circular import dependency; schema
relies on common, but common.build_params requires a type annotation
from schema. To type this properly, it needs to be moved outside the
cycle.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
---
 scripts/qapi/commands.py |  9 +++++++--
 scripts/qapi/common.py   | 23 -----------------------
 scripts/qapi/events.py   |  9 ++-------
 scripts/qapi/gen.py      | 31 +++++++++++++++++++++++++++++--
 4 files changed, 38 insertions(+), 34 deletions(-)

Comments

Markus Armbruster Oct. 7, 2020, 9:21 a.m. UTC | #1
John Snow <jsnow@redhat.com> writes:

> Including it in common.py creates a circular import dependency; schema
> relies on common, but common.build_params requires a type annotation
> from schema. To type this properly, it needs to be moved outside the
> cycle.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> Reviewed-by: Cleber Rosa <crosa@redhat.com>
> ---
>  scripts/qapi/commands.py |  9 +++++++--
>  scripts/qapi/common.py   | 23 -----------------------
>  scripts/qapi/events.py   |  9 ++-------
>  scripts/qapi/gen.py      | 31 +++++++++++++++++++++++++++++--
>  4 files changed, 38 insertions(+), 34 deletions(-)
>
> diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
> index 5dc2f5a9fa8..f67393f8713 100644
> --- a/scripts/qapi/commands.py
> +++ b/scripts/qapi/commands.py
> @@ -13,8 +13,13 @@
>  See the COPYING file in the top-level directory.
>  """
>  
> -from .common import build_params, c_name, mcgen
> -from .gen import QAPIGenCCode, QAPISchemaModularCVisitor, ifcontext
> +from .common import c_name, mcgen
> +from .gen import (
> +    QAPIGenCCode,
> +    QAPISchemaModularCVisitor,
> +    build_params,
> +    ifcontext,
> +)
>  
>  
>  def gen_command_decl(name, arg_type, boxed, ret_type):
> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
> index 0ef38ea5fe0..9ab0685cc51 100644
> --- a/scripts/qapi/common.py
> +++ b/scripts/qapi/common.py
> @@ -209,26 +209,3 @@ def gen_endif(ifcond: Sequence[str]) -> str:
>  #endif /* %(cond)s */
>  ''', cond=ifc)
>      return ret
> -
> -
> -def build_params(arg_type,
> -                 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'
> diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
> index 6b3afa14d72..f840a62ed92 100644
> --- a/scripts/qapi/events.py
> +++ b/scripts/qapi/events.py
> @@ -12,13 +12,8 @@
>  See the COPYING file in the top-level directory.
>  """
>  
> -from .common import (
> -    build_params,
> -    c_enum_const,
> -    c_name,
> -    mcgen,
> -)
> -from .gen import QAPISchemaModularCVisitor, ifcontext
> +from .common import c_enum_const, c_name, mcgen
> +from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
>  from .schema import QAPISchemaEnumMember
>  from .types import gen_enum, gen_enum_lookup
>  
> diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
> index 1fed712b43b..f2e2746fea5 100644
> --- a/scripts/qapi/gen.py
> +++ b/scripts/qapi/gen.py
> @@ -2,9 +2,11 @@
>  #
>  # QAPI code generation
>  #
> -# Copyright (c) 2018-2019 Red Hat Inc.
> +# Copyright IBM, Corp. 2011
> +# Copyright (c) 2013-2019 Red Hat Inc.
>  #
>  # Authors:
> +#  Anthony Liguori <aliguori@us.ibm.com>
>  #  Markus Armbruster <armbru@redhat.com>
>  #  Marc-André Lureau <marcandre.lureau@redhat.com>
>  #

The code you move into this file is actually Red Hat's:

$ git-log -L174,193:scripts/qapi/common.py master| egrep 'Author|Date'
Author: Markus Armbruster <armbru@redhat.com>
Date:   Wed Aug 15 21:37:36 2018 +0800
Author: Marc-André Lureau <marcandre.lureau@redhat.com>
Date:   Thu Jun 1 16:41:41 2017 +0400
Author: Eric Blake <eblake@redhat.com>
Date:   Wed Jul 13 21:50:20 2016 -0600
Author: Eric Blake <eblake@redhat.com>
Date:   Wed Jul 13 21:50:19 2016 -0600
Author: Eric Blake <eblake@redhat.com>
Date:   Thu Mar 17 16:48:28 2016 -0600
Author: Markus Armbruster <armbru@redhat.com>
Date:   Wed Sep 16 13:06:20 2015 +0200

So the correct update is simply

   #
   # QAPI code generation
   #
  -# Copyright (c) 2018-2019 Red Hat Inc.
  +# Copyright (c) 2015-2019 Red Hat Inc.
   #
   # Authors:
   #  Markus Armbruster <armbru@redhat.com>
   #  Marc-André Lureau <marcandre.lureau@redhat.com>
   #

> @@ -15,16 +17,18 @@
>  import errno
>  import os
>  import re
> +from typing import Optional
>  
>  from .common import (
>      c_fname,
> +    c_name,
>      gen_endif,
>      gen_if,
>      guardend,
>      guardstart,
>      mcgen,
>  )
> -from .schema import QAPISchemaVisitor
> +from .schema import QAPISchemaObjectType, QAPISchemaVisitor
>  
>  
>  class QAPIGen:
> @@ -90,6 +94,29 @@ def _wrap_ifcond(ifcond, before, after):
>      return out
>  
>  
> +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'
> +
> +
>  class QAPIGenCCode(QAPIGen):
>  
>      def __init__(self, fname):
John Snow Oct. 7, 2020, 3:26 p.m. UTC | #2
On 10/7/20 5:21 AM, Markus Armbruster wrote:
> John Snow <jsnow@redhat.com> writes:
> 
>> Including it in common.py creates a circular import dependency; schema
>> relies on common, but common.build_params requires a type annotation
>> from schema. To type this properly, it needs to be moved outside the
>> cycle.
>>
>> Signed-off-by: John Snow <jsnow@redhat.com>
>> Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
>> Reviewed-by: Cleber Rosa <crosa@redhat.com>
>> ---
>>   scripts/qapi/commands.py |  9 +++++++--
>>   scripts/qapi/common.py   | 23 -----------------------
>>   scripts/qapi/events.py   |  9 ++-------
>>   scripts/qapi/gen.py      | 31 +++++++++++++++++++++++++++++--
>>   4 files changed, 38 insertions(+), 34 deletions(-)
>>
>> diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
>> index 5dc2f5a9fa8..f67393f8713 100644
>> --- a/scripts/qapi/commands.py
>> +++ b/scripts/qapi/commands.py
>> @@ -13,8 +13,13 @@
>>   See the COPYING file in the top-level directory.
>>   """
>>   
>> -from .common import build_params, c_name, mcgen
>> -from .gen import QAPIGenCCode, QAPISchemaModularCVisitor, ifcontext
>> +from .common import c_name, mcgen
>> +from .gen import (
>> +    QAPIGenCCode,
>> +    QAPISchemaModularCVisitor,
>> +    build_params,
>> +    ifcontext,
>> +)
>>   
>>   
>>   def gen_command_decl(name, arg_type, boxed, ret_type):
>> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
>> index 0ef38ea5fe0..9ab0685cc51 100644
>> --- a/scripts/qapi/common.py
>> +++ b/scripts/qapi/common.py
>> @@ -209,26 +209,3 @@ def gen_endif(ifcond: Sequence[str]) -> str:
>>   #endif /* %(cond)s */
>>   ''', cond=ifc)
>>       return ret
>> -
>> -
>> -def build_params(arg_type,
>> -                 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'
>> diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
>> index 6b3afa14d72..f840a62ed92 100644
>> --- a/scripts/qapi/events.py
>> +++ b/scripts/qapi/events.py
>> @@ -12,13 +12,8 @@
>>   See the COPYING file in the top-level directory.
>>   """
>>   
>> -from .common import (
>> -    build_params,
>> -    c_enum_const,
>> -    c_name,
>> -    mcgen,
>> -)
>> -from .gen import QAPISchemaModularCVisitor, ifcontext
>> +from .common import c_enum_const, c_name, mcgen
>> +from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
>>   from .schema import QAPISchemaEnumMember
>>   from .types import gen_enum, gen_enum_lookup
>>   
>> diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
>> index 1fed712b43b..f2e2746fea5 100644
>> --- a/scripts/qapi/gen.py
>> +++ b/scripts/qapi/gen.py
>> @@ -2,9 +2,11 @@
>>   #
>>   # QAPI code generation
>>   #
>> -# Copyright (c) 2018-2019 Red Hat Inc.
>> +# Copyright IBM, Corp. 2011
>> +# Copyright (c) 2013-2019 Red Hat Inc.
>>   #
>>   # Authors:
>> +#  Anthony Liguori <aliguori@us.ibm.com>
>>   #  Markus Armbruster <armbru@redhat.com>
>>   #  Marc-André Lureau <marcandre.lureau@redhat.com>
>>   #
> 
> The code you move into this file is actually Red Hat's:
> 
> $ git-log -L174,193:scripts/qapi/common.py master| egrep 'Author|Date'
> Author: Markus Armbruster <armbru@redhat.com>
> Date:   Wed Aug 15 21:37:36 2018 +0800
> Author: Marc-André Lureau <marcandre.lureau@redhat.com>
> Date:   Thu Jun 1 16:41:41 2017 +0400
> Author: Eric Blake <eblake@redhat.com>
> Date:   Wed Jul 13 21:50:20 2016 -0600
> Author: Eric Blake <eblake@redhat.com>
> Date:   Wed Jul 13 21:50:19 2016 -0600
> Author: Eric Blake <eblake@redhat.com>
> Date:   Thu Mar 17 16:48:28 2016 -0600
> Author: Markus Armbruster <armbru@redhat.com>
> Date:   Wed Sep 16 13:06:20 2015 +0200
> 
> So the correct update is simply
> 
>     #
>     # QAPI code generation
>     #
>    -# Copyright (c) 2018-2019 Red Hat Inc.
>    +# Copyright (c) 2015-2019 Red Hat Inc.
>     #
>     # Authors:
>     #  Markus Armbruster <armbru@redhat.com>
>     #  Marc-André Lureau <marcandre.lureau@redhat.com>
>     #
> 

OK, thank you. I did the dumbest possibly correct thing. My appetite for 
doing line ownership analysis is ... low.

>> @@ -15,16 +17,18 @@
>>   import errno
>>   import os
>>   import re
>> +from typing import Optional
>>   
>>   from .common import (
>>       c_fname,
>> +    c_name,
>>       gen_endif,
>>       gen_if,
>>       guardend,
>>       guardstart,
>>       mcgen,
>>   )
>> -from .schema import QAPISchemaVisitor
>> +from .schema import QAPISchemaObjectType, QAPISchemaVisitor
>>   
>>   
>>   class QAPIGen:
>> @@ -90,6 +94,29 @@ def _wrap_ifcond(ifcond, before, after):
>>       return out
>>   
>>   
>> +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'
>> +
>> +
>>   class QAPIGenCCode(QAPIGen):
>>   
>>       def __init__(self, fname):
Eduardo Habkost Oct. 7, 2020, 6:10 p.m. UTC | #3
On Wed, Oct 07, 2020 at 11:21:51AM +0200, Markus Armbruster wrote:
> John Snow <jsnow@redhat.com> writes:
> 
> > Including it in common.py creates a circular import dependency; schema
> > relies on common, but common.build_params requires a type annotation
> > from schema. To type this properly, it needs to be moved outside the
> > cycle.
> >
> > Signed-off-by: John Snow <jsnow@redhat.com>
> > Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
> > Reviewed-by: Cleber Rosa <crosa@redhat.com>
> > ---
> >  scripts/qapi/commands.py |  9 +++++++--
> >  scripts/qapi/common.py   | 23 -----------------------
> >  scripts/qapi/events.py   |  9 ++-------
> >  scripts/qapi/gen.py      | 31 +++++++++++++++++++++++++++++--
> >  4 files changed, 38 insertions(+), 34 deletions(-)
> >
> > diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
> > index 5dc2f5a9fa8..f67393f8713 100644
> > --- a/scripts/qapi/commands.py
> > +++ b/scripts/qapi/commands.py
> > @@ -13,8 +13,13 @@
> >  See the COPYING file in the top-level directory.
> >  """
> >  
> > -from .common import build_params, c_name, mcgen
> > -from .gen import QAPIGenCCode, QAPISchemaModularCVisitor, ifcontext
> > +from .common import c_name, mcgen
> > +from .gen import (
> > +    QAPIGenCCode,
> > +    QAPISchemaModularCVisitor,
> > +    build_params,
> > +    ifcontext,
> > +)
> >  
> >  
> >  def gen_command_decl(name, arg_type, boxed, ret_type):
> > diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
> > index 0ef38ea5fe0..9ab0685cc51 100644
> > --- a/scripts/qapi/common.py
> > +++ b/scripts/qapi/common.py
> > @@ -209,26 +209,3 @@ def gen_endif(ifcond: Sequence[str]) -> str:
> >  #endif /* %(cond)s */
> >  ''', cond=ifc)
> >      return ret
> > -
> > -
> > -def build_params(arg_type,
> > -                 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'
> > diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
> > index 6b3afa14d72..f840a62ed92 100644
> > --- a/scripts/qapi/events.py
> > +++ b/scripts/qapi/events.py
> > @@ -12,13 +12,8 @@
> >  See the COPYING file in the top-level directory.
> >  """
> >  
> > -from .common import (
> > -    build_params,
> > -    c_enum_const,
> > -    c_name,
> > -    mcgen,
> > -)
> > -from .gen import QAPISchemaModularCVisitor, ifcontext
> > +from .common import c_enum_const, c_name, mcgen
> > +from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
> >  from .schema import QAPISchemaEnumMember
> >  from .types import gen_enum, gen_enum_lookup
> >  
> > diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
> > index 1fed712b43b..f2e2746fea5 100644
> > --- a/scripts/qapi/gen.py
> > +++ b/scripts/qapi/gen.py
> > @@ -2,9 +2,11 @@
> >  #
> >  # QAPI code generation
> >  #
> > -# Copyright (c) 2018-2019 Red Hat Inc.
> > +# Copyright IBM, Corp. 2011
> > +# Copyright (c) 2013-2019 Red Hat Inc.
> >  #
> >  # Authors:
> > +#  Anthony Liguori <aliguori@us.ibm.com>
> >  #  Markus Armbruster <armbru@redhat.com>
> >  #  Marc-André Lureau <marcandre.lureau@redhat.com>
> >  #
> 
> The code you move into this file is actually Red Hat's:
> 
> $ git-log -L174,193:scripts/qapi/common.py master| egrep 'Author|Date'
> Author: Markus Armbruster <armbru@redhat.com>
> Date:   Wed Aug 15 21:37:36 2018 +0800
> Author: Marc-André Lureau <marcandre.lureau@redhat.com>
> Date:   Thu Jun 1 16:41:41 2017 +0400
> Author: Eric Blake <eblake@redhat.com>
> Date:   Wed Jul 13 21:50:20 2016 -0600
> Author: Eric Blake <eblake@redhat.com>
> Date:   Wed Jul 13 21:50:19 2016 -0600
> Author: Eric Blake <eblake@redhat.com>
> Date:   Thu Mar 17 16:48:28 2016 -0600
> Author: Markus Armbruster <armbru@redhat.com>
> Date:   Wed Sep 16 13:06:20 2015 +0200
> 
> So the correct update is simply
> 
>    #
>    # QAPI code generation
>    #
>   -# Copyright (c) 2018-2019 Red Hat Inc.
>   +# Copyright (c) 2015-2019 Red Hat Inc.
>    #
>    # Authors:
>    #  Markus Armbruster <armbru@redhat.com>
>    #  Marc-André Lureau <marcandre.lureau@redhat.com>
>    #

I am pretty sure build_params() below is a derivative work of
generate_command_decl(), added in commit c17d9908a942 ("qapi: add
qapi-commands.py code generator"), copyright IBM Corp.  I'm not a
lawyer, though.

Because figuring that out is complicated, when I move or copy
code between files, I either:
(a) copy no copyright notices from the other file, or
(b) copy all copyright notices from the other files.

(The above is a description of what I do, but it is not a
suggestion on how to proceed on this case.)

> 
> > @@ -15,16 +17,18 @@
> >  import errno
> >  import os
> >  import re
> > +from typing import Optional
> >  
> >  from .common import (
> >      c_fname,
> > +    c_name,
> >      gen_endif,
> >      gen_if,
> >      guardend,
> >      guardstart,
> >      mcgen,
> >  )
> > -from .schema import QAPISchemaVisitor
> > +from .schema import QAPISchemaObjectType, QAPISchemaVisitor
> >  
> >  
> >  class QAPIGen:
> > @@ -90,6 +94,29 @@ def _wrap_ifcond(ifcond, before, after):
> >      return out
> >  
> >  
> > +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'
> > +
> > +
> >  class QAPIGenCCode(QAPIGen):
> >  
> >      def __init__(self, fname):
diff mbox series

Patch

diff --git a/scripts/qapi/commands.py b/scripts/qapi/commands.py
index 5dc2f5a9fa8..f67393f8713 100644
--- a/scripts/qapi/commands.py
+++ b/scripts/qapi/commands.py
@@ -13,8 +13,13 @@ 
 See the COPYING file in the top-level directory.
 """
 
-from .common import build_params, c_name, mcgen
-from .gen import QAPIGenCCode, QAPISchemaModularCVisitor, ifcontext
+from .common import c_name, mcgen
+from .gen import (
+    QAPIGenCCode,
+    QAPISchemaModularCVisitor,
+    build_params,
+    ifcontext,
+)
 
 
 def gen_command_decl(name, arg_type, boxed, ret_type):
diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 0ef38ea5fe0..9ab0685cc51 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -209,26 +209,3 @@  def gen_endif(ifcond: Sequence[str]) -> str:
 #endif /* %(cond)s */
 ''', cond=ifc)
     return ret
-
-
-def build_params(arg_type,
-                 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'
diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py
index 6b3afa14d72..f840a62ed92 100644
--- a/scripts/qapi/events.py
+++ b/scripts/qapi/events.py
@@ -12,13 +12,8 @@ 
 See the COPYING file in the top-level directory.
 """
 
-from .common import (
-    build_params,
-    c_enum_const,
-    c_name,
-    mcgen,
-)
-from .gen import QAPISchemaModularCVisitor, ifcontext
+from .common import c_enum_const, c_name, mcgen
+from .gen import QAPISchemaModularCVisitor, build_params, ifcontext
 from .schema import QAPISchemaEnumMember
 from .types import gen_enum, gen_enum_lookup
 
diff --git a/scripts/qapi/gen.py b/scripts/qapi/gen.py
index 1fed712b43b..f2e2746fea5 100644
--- a/scripts/qapi/gen.py
+++ b/scripts/qapi/gen.py
@@ -2,9 +2,11 @@ 
 #
 # QAPI code generation
 #
-# Copyright (c) 2018-2019 Red Hat Inc.
+# Copyright IBM, Corp. 2011
+# Copyright (c) 2013-2019 Red Hat Inc.
 #
 # Authors:
+#  Anthony Liguori <aliguori@us.ibm.com>
 #  Markus Armbruster <armbru@redhat.com>
 #  Marc-André Lureau <marcandre.lureau@redhat.com>
 #
@@ -15,16 +17,18 @@ 
 import errno
 import os
 import re
+from typing import Optional
 
 from .common import (
     c_fname,
+    c_name,
     gen_endif,
     gen_if,
     guardend,
     guardstart,
     mcgen,
 )
-from .schema import QAPISchemaVisitor
+from .schema import QAPISchemaObjectType, QAPISchemaVisitor
 
 
 class QAPIGen:
@@ -90,6 +94,29 @@  def _wrap_ifcond(ifcond, before, after):
     return out
 
 
+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'
+
+
 class QAPIGenCCode(QAPIGen):
 
     def __init__(self, fname):