From 7ce106a96feee4d46bfcdb47127b0935804c9357 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 17 Mar 2016 16:48:30 -0600 Subject: qapi: Emit implicit structs in generated C We already have several places that want to visit all the members of an implicit object within a larger context (simple union variant, event with anonymous data, command with anonymous arguments struct); and will be adding another one soon (the ability to declare an anonymous base for a flat union). Having a C struct declared for these implicit types, along with a visit_type_FOO_members() helper function, will make for fewer special cases in our generator. We do not, however, need qapi_free_FOO() or visit_type_FOO() functions for implicit types, because they should not be used directly outside of the generated code. This is done by adding a conditional in visit_object_type() for both qapi-types.py and qapi-visit.py based on the object name. The comparison of "name.startswith('q_')" is a bit hacky (it's basically duplicating what .is_implicit() already uses), but beats changing the signature of the visit_object_type() callback to pass a new 'implicit' flag. The hack should be temporary: we are considering adding a future patch that consolidates the narrow visit_object_type(..., base, local_members, variants) and visit_object_type_flat(..., all_members, variants) [where different sets of information are already broken out, and the QAPISchemaObjectType is no longer available] into a broader visit_object_type(obj_type) [where the visitor can query the needed fields from obj_type directly]. Also, now that we WANT to output C code for implicits, we no longer need the visit_needed() filter, leaving 'q_empty' as the only object still needing a special case. Remember, 'q_empty' is the only built-in generated object, which means that without a special case it would be emitted in multiple files (the main qapi-types.h and in qga-qapi-types.h) causing compilation failure due to redefinition. But since it has no members, it's easier to just avoid an attempt to visit that particular type; since gen_object() is called recursively, we also prime the objects_seen set to cover any recursion into the empty type. The patch relies on the changed naming of implicit types in the previous patch. It is a bit unfortunate that the generated struct names and visit_type_FOO_members() don't match normal naming conventions, but it's not too bad, since they will only be used in generated code. The generated code grows substantially in size: the implicit '-wrapper' types must be emitted in qapi-types.h before any union can include an unboxed member of that type. Arguably, the '-args' types could be emitted in a private header for just qapi-visit.c and qmp-marshal.c, rather than polluting qapi-types.h; but adding complexity to the generator to split the output location according to role doesn't seem worth the maintenance costs. Signed-off-by: Eric Blake Message-Id: <1458254921-17042-6-git-send-email-eblake@redhat.com> Signed-off-by: Markus Armbruster --- scripts/qapi.py | 2 -- 1 file changed, 2 deletions(-) (limited to 'scripts/qapi.py') diff --git a/scripts/qapi.py b/scripts/qapi.py index f6701f50c5..96fb216ce2 100644 --- a/scripts/qapi.py +++ b/scripts/qapi.py @@ -1000,7 +1000,6 @@ class QAPISchemaObjectType(QAPISchemaType): return self.name.startswith('q_') def c_name(self): - assert not self.is_implicit() return QAPISchemaType.c_name(self) def c_type(self): @@ -1008,7 +1007,6 @@ class QAPISchemaObjectType(QAPISchemaType): return c_name(self.name) + pointer_suffix def c_unboxed_type(self): - assert not self.is_implicit() return c_name(self.name) def json_type(self): -- cgit v1.2.3