Re: [PATCH] qapi: Fix code generation with Python 3.5

[Markus Armbruster <armbru@redhat.com>]

John Snow <jsnow@redhat.com> writes:

> On 1/16/20 3:25 PM, Markus Armbruster wrote:
>> Recent commit 3e7fb5811b "qapi: Fix code generation for empty modules"
>> modules" switched QAPISchema.visit() from
>> 
>>     for entity in self._entity_list:
>> 
>> effectively to
>> 
>>     for mod in self._module_dict.values():
>>         for entity in mod._entity_list:
>> 
>> Visits in the same order as long as .values() is in insertion order.
>> That's the case only for Python 3.6 and later.  Before, it's in some
>> arbitrary order, which results in broken generated code.
>> 
>> Fix by making self._module_dict an OrderedDict rather than a dict.
>> 
>> Fixes: 3e7fb5811baab213dcc7149c3aa69442d683c26c
>> Signed-off-by: Markus Armbruster <armbru@redhat.com>
>> ---
>>  scripts/qapi/schema.py | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py
>> index 0bfc5256fb..5100110fa2 100644
>> --- a/scripts/qapi/schema.py
>> +++ b/scripts/qapi/schema.py
>> @@ -795,7 +795,7 @@ class QAPISchema(object):
>>          self.docs = parser.docs
>>          self._entity_list = []
>>          self._entity_dict = {}
>> -        self._module_dict = {}
>> +        self._module_dict = OrderedDict()
>>          self._schema_dir = os.path.dirname(fname)
>>          self._make_module(None) # built-ins
>>          self._make_module(fname)
>> 
>
> This problem has bitten me *many* times. I'm wondering if there's a
> prescription that isn't just "Wait until we can stipulate 3.6+".

No clue.

3.5 EOL is scheduled for 2020-09-13.
https://devguide.python.org/#status-of-python-branches

We support 3.5 because we support Debian 9.

We'd normally drop support for Debian 9 two years after Debian 10,
i.e. July 2021.  Assuming Debian supports it that far.  Whether they can
truly support Python 3.5 after uptstream EOL seems doubtful.