From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49611) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmwQw-00007l-HF for qemu-devel@nongnu.org; Fri, 16 Oct 2015 00:16:02 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZmwQs-0004ZN-5T for qemu-devel@nongnu.org; Fri, 16 Oct 2015 00:15:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45823) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZmwQr-0004Z5-SH for qemu-devel@nongnu.org; Fri, 16 Oct 2015 00:15:54 -0400 From: Eric Blake Date: Thu, 15 Oct 2015 22:15:41 -0600 Message-Id: <1444968943-11254-17-git-send-email-eblake@redhat.com> In-Reply-To: <1444968943-11254-1-git-send-email-eblake@redhat.com> References: <1444968943-11254-1-git-send-email-eblake@redhat.com> Subject: [Qemu-devel] [PATCH v9 16/17] qapi: Finish converting to new qapi union layout List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: armbru@redhat.com, Michael Roth We have two issues with our qapi union layout: 1) Even though the QMP wire format spells the tag 'type', the C code spells it 'kind', requiring some hacks in the generator. 2) The C struct uses an anonymous union, which places all tag values in the same namespace as all non-variant members. This leads to spurious collisions if a tag value matches a QMP name. This patch is the back end for a series that converts to a saner qapi union layout. Now that all clients have been converted to use 'type' and 'obj->u.value', we can drop the temporary support for 'kind' and 'obj->value', and undo the temporary restriction against 'u' as a branch name. Given a simple union qapi type: { 'union':'Foo', 'data': { 'a':'int', 'b':'bool' } } this is the overall effect, when compared to the state before this series of patches: | struct Foo { |- FooKind kind; |- union { /* union tag is @kind */ |+ FooKind type; |+ union { /* union tag is @type */ | void *data; | int64_t a; | bool b; |- }; |+ } u; | }; Note, however, that we do not rename the generated enum, which is still 'FooKind'. A further patch could generate implicit enums as 'FooType', but that causes more churn to C code, and gets harder since the generator already reserved the '*Kind' namespace, but there are already QMP constructs with '*Type' naming which means we cannot easily reserve it for qapi. Signed-off-by: Eric Blake --- v9: new patch, but incorporates parts of v5 31/46 and Markus' RFC: http://lists.gnu.org/archive/html/qemu-devel/2015-10/msg02236.html --- scripts/qapi-types.py | 26 +++++--------------------- tests/qapi-schema/qapi-schema-test.json | 4 +--- tests/qapi-schema/qapi-schema-test.out | 4 ++-- 3 files changed, 8 insertions(+), 26 deletions(-) diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py index 0a14451..4ba39b6 100644 --- a/scripts/qapi-types.py +++ b/scripts/qapi-types.py @@ -136,23 +136,10 @@ struct %(c_name)s { if base: ret += gen_struct_fields([], base) else: - # TODO As a hack, we emit both 'kind' and 'type'. Ultimately, we - # want to use only 'type', but the conversion is large enough to - # require staging over several commits. - ret += mcgen(''' - union { - %(c_type)s kind; - %(c_type)s type; - }; -''', - c_type=c_name(variants.tag_member.type.name)) + ret += gen_struct_field(variants.tag_member.name, + variants.tag_member.type, + False) - # TODO As a hack, we emit the union twice, once as an anonymous union - # and once as a named union. Ultimately, we want to use only the - # named union version (as it avoids conflicts between tag values as - # branch names competing with non-variant QMP names), but the conversion - # is large enough to require staging over several commits. - tmp = '' # FIXME: What purpose does data serve, besides preventing a union that # has a branch named 'data'? We use it in qapi-visit.py to decide # whether to bypass the switch statement if visiting the discriminator @@ -161,7 +148,7 @@ struct %(c_name)s { # should not be any data leaks even without a data pointer. Or, if # 'data' is merely added to guarantee we don't have an empty union, # shouldn't we enforce that at .json parse time? - tmp += mcgen(''' + ret += mcgen(''' union { /* union tag is @%(c_name)s */ void *data; ''', @@ -170,17 +157,14 @@ struct %(c_name)s { for var in variants.variants: # Ugly special case for simple union TODO get rid of it typ = var.simple_union_type() or var.type - tmp += mcgen(''' + ret += mcgen(''' %(c_type)s %(c_name)s; ''', c_type=typ.c_type(), c_name=c_name(var.name)) - ret += tmp - ret += ' ' + '\n '.join(tmp.split('\n')) ret += mcgen(''' } u; - }; }; ''') diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json index 876ce18..22e15eb 100644 --- a/tests/qapi-schema/qapi-schema-test.json +++ b/tests/qapi-schema/qapi-schema-test.json @@ -113,10 +113,8 @@ # should still be valid as a type or union branch name. And although # '*Kind' and '*List' are forbidden as type names, they should not be # forbidden as a member or branch name. -# TODO - we temporarily do not support 'u' as branch name, while converting -# code to use the new union layout { 'struct': 'has_a', 'data': { 'MyKind': 'int', 'MyList': ['int'] } } -{ 'union': 'u', 'data': { 'u8': 'uint8', 'myKind': 'has_a', +{ 'union': 'u', 'data': { 'u': 'uint8', 'myKind': 'has_a', 'myList': 'has_a' } } # testing commands diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out index cb12435..feaf20d 100644 --- a/tests/qapi-schema/qapi-schema-test.out +++ b/tests/qapi-schema/qapi-schema-test.out @@ -202,10 +202,10 @@ object has_a member MyKind: int optional=False member MyList: intList optional=False object u - case u8: :obj-uint8-wrapper + case u: :obj-uint8-wrapper case myKind: :obj-has_a-wrapper case myList: :obj-has_a-wrapper -enum uKind ['u8', 'myKind', 'myList'] +enum uKind ['u', 'myKind', 'myList'] command user_def_cmd None -> None gen=True success_response=True command user_def_cmd1 :obj-user_def_cmd1-arg -> None -- 2.4.3