Re: [PATCH v3 09/20] qapi/schema: assert resolve_type has 'info' and 'what' args on error

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> resolve_type() is generally used to resolve configuration-provided type
> names into type objects, and generally requires valid 'info' and 'what'
> parameters.
>
> In some cases, such as with QAPISchemaArrayType.check(), resolve_type
> may be used to resolve built-in types and as such will not have an
> 'info' argument, but also must not fail in this scenario.
>
> Use an assertion to sate mypy that we will indeed have 'info' and 'what'
> parameters for the error pathway in resolve_type.
>
> Note: there are only three callsites to resolve_type at present where
> "info" is perceived to be possibly None:

Who is the perceiver?  mypy?

>
>     1) QAPISchemaArrayType.check()
>     2) QAPISchemaObjectTypeMember.check()
>     3) QAPISchemaEvent.check()
>
>     Of those three, only the first actually ever passes None; the other two
>     are limited by their base class initializers which accept info=None, but
>     neither subclass actually use a None value in practice, currently.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/schema.py | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
> index e617abb03af..573be7275a6 100644
> --- a/scripts/qapi/schema.py
> +++ b/scripts/qapi/schema.py
> @@ -1004,6 +1004,7 @@ def lookup_type(self, name):
>      def resolve_type(self, name, info, what):
>          typ = self.lookup_type(name)
>          if not typ:
> +            assert info and what  # built-in types must not fail lookup
>              if callable(what):
>                  what = what(info)
>              raise QAPISemError(
<