Re: [PATCH 07/19] qapi/introspect: assert schema.lookup_type did not fail

[Markus Armbruster]

John Snow <jsnow@redhat.com> writes:

> lookup_type() is capable of returning None, but introspect.py isn't
> prepared for that. (And rightly so, if these built-in types are absent,
> something has gone hugely wrong.)
>
> RFC: This is slightly cumbersome as-is, but a patch at the end of this series
> tries to address it with some slightly slicker lookup functions that
> don't need as much hand-holding.
>
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/introspect.py | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/qapi/introspect.py b/scripts/qapi/introspect.py
> index 67c7d89aae0..42981bce163 100644
> --- a/scripts/qapi/introspect.py
> +++ b/scripts/qapi/introspect.py
> @@ -227,10 +227,14 @@ def _use_type(self, typ: QAPISchemaType) -> str:
>  
>          # Map the various integer types to plain int
>          if typ.json_type() == 'int':
> -            typ = self._schema.lookup_type('int')
> +            tmp = self._schema.lookup_type('int')
> +            assert tmp is not None

More laconic: assert tmp

> +            typ = tmp
>          elif (isinstance(typ, QAPISchemaArrayType) and
>                typ.element_type.json_type() == 'int'):
> -            typ = self._schema.lookup_type('intList')
> +            tmp = self._schema.lookup_type('intList')
> +            assert tmp is not None
> +            typ = tmp
>          # Add type to work queue if new
>          if typ not in self._used_types:
>              self._used_types.append(typ)

Not fond of naming things @tmp, but I don't have a better name to offer.

We could avoid the lookup by having _def_predefineds() set suitable
attributes, like it serts .the_empty_object_type.  Matter of taste.  Not
now unless you want to.