A struct's 'data' must be a JSON object defining the struct's members.
The QAPI code generator incorrectly accepts a JSON string instead, and
then crashes in QAPISchema._make_members() called from
._def_struct_type().
Fix to reject it: factor check_type_implicit() out of
check_type_name_or_implicit(), and switch check_struct() to use it
instead. Also add a test case.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20230316071325.492471-9-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[More detailed commit message]