[Qemu-devel] [PATCH v3 10/10] qapi: Drop useless 'data' member of unions

[Eric Blake]

We started moving away from the use of the 'void *data' member
in the C union corresponding to a QAPI union back in commit
544a373; recent commits have gotten rid of other uses.  Now
that it is completely unused, we can remove the member itself
as well as the FIXME comment.  Update the testsuite to drop the
negative test union-clash-data.

Signed-off-by: Eric Blake <address@hidden>
Reviewed-by: Daniel P. Berrange <address@hidden>

---
v3: reword commit message, drop positive test addition
v2: add R-b
v1: drop patch that forced :empty as base to all structs
Previously posted as part of qapi cleanup subset F:
v6: rebase to earlier changes
---
 scripts/qapi-types.py                   | 9 ---------
 tests/Makefile                          | 1 -
 tests/qapi-schema/union-clash-data.err  | 0
 tests/qapi-schema/union-clash-data.exit | 1 -
 tests/qapi-schema/union-clash-data.json | 7 -------
 tests/qapi-schema/union-clash-data.out  | 9 ---------
 6 files changed, 27 deletions(-)
 delete mode 100644 tests/qapi-schema/union-clash-data.err
 delete mode 100644 tests/qapi-schema/union-clash-data.exit
 delete mode 100644 tests/qapi-schema/union-clash-data.json
 delete mode 100644 tests/qapi-schema/union-clash-data.out

diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 19d1fff..0306a88 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -116,17 +116,8 @@ static inline %(base)s *qapi_%(c_name)s_base(const 
%(c_name)s *obj)


 def gen_variants(variants):
-    # 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
-    # failed; but since we 0-initialize structs, and cannot tell what
-    # branch of the union is in use if the discriminator is invalid, there
-    # 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?
     ret = mcgen('''
     union { /* union tag is @%(c_name)s */
-        void *data;
 ''',
                 c_name=c_name(variants.tag_member.name))

diff --git a/tests/Makefile b/tests/Makefile
index 04e34b5..cd4bbd4 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -358,7 +358,6 @@ qapi-schema += unicode-str.json
 qapi-schema += union-base-no-discriminator.json
 qapi-schema += union-branch-case.json
 qapi-schema += union-clash-branches.json
-qapi-schema += union-clash-data.json
 qapi-schema += union-empty.json
 qapi-schema += union-invalid-base.json
 qapi-schema += union-optional-branch.json
diff --git a/tests/qapi-schema/union-clash-data.err 
b/tests/qapi-schema/union-clash-data.err
deleted file mode 100644
index e69de29..0000000
diff --git a/tests/qapi-schema/union-clash-data.exit 
b/tests/qapi-schema/union-clash-data.exit
deleted file mode 100644
index 573541a..0000000
--- a/tests/qapi-schema/union-clash-data.exit
+++ /dev/null
@@ -1 +0,0 @@
-0
diff --git a/tests/qapi-schema/union-clash-data.json 
b/tests/qapi-schema/union-clash-data.json
deleted file mode 100644
index 7308e69..0000000
--- a/tests/qapi-schema/union-clash-data.json
+++ /dev/null
@@ -1,7 +0,0 @@
-# Union branch 'data'
-# FIXME: this parses, but then fails to compile due to a duplicate 'data'
-# (one from the branch name, another as a filler to avoid an empty union).
-# we should either detect the collision at parse time, or change the
-# generated struct to allow this to compile.
-{ 'union': 'TestUnion',
-  'data': { 'data': 'int' } }
diff --git a/tests/qapi-schema/union-clash-data.out 
b/tests/qapi-schema/union-clash-data.out
deleted file mode 100644
index f5752f4..0000000
--- a/tests/qapi-schema/union-clash-data.out
+++ /dev/null
@@ -1,9 +0,0 @@
-object :empty
-object :obj-int-wrapper
-    member data: int optional=False
-enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 
'qbool']
-    prefix QTYPE
-object TestUnion
-    member type: TestUnionKind optional=False
-    case data: :obj-int-wrapper
-enum TestUnionKind ['data']
-- 
2.5.0