[Qemu-devel] [PATCH v6 10/12] qapi: Correct error for union branch 'kind' clash

[Eric Blake <eblake@redhat.com>]

The error message when a simple union or alternate contains a
branch named 'kind' is ugly, because it is tied to the Schema
member named 'type'.  A future patch will fix the generated C
to match QMP, but until that point, we can hack things with
a temporary subclass to make the error message reflect the
actually collision.

Rename alternate-clash to alternate-clash-members, and add a
new test alternate-clash-type.  While similar to the earlier
addition of union-clash-type, we have one major difference: a
future patch will be simplifying alternates to not need an
implict AlternateKind enum, but we still need to detect the
collision with the resulting C 'qtype_code type;' tag.

No change to generated code.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v6: New patch
---
 scripts/qapi.py                                            | 14 ++++++++++++++
 tests/Makefile                                             |  3 ++-
 tests/qapi-schema/alternate-clash-members.err              |  1 +
 .../{alternate-clash.exit => alternate-clash-members.exit} |  0
 .../{alternate-clash.json => alternate-clash-members.json} |  0
 .../{alternate-clash.out => alternate-clash-members.out}   |  0
 tests/qapi-schema/alternate-clash-type.err                 |  1 +
 tests/qapi-schema/alternate-clash-type.exit                |  1 +
 tests/qapi-schema/alternate-clash-type.json                | 10 ++++++++++
 tests/qapi-schema/alternate-clash-type.out                 |  0
 tests/qapi-schema/alternate-clash.err                      |  1 -
 tests/qapi-schema/union-clash-type.err                     |  2 +-
 tests/qapi-schema/union-clash-type.json                    |  2 --
 13 files changed, 30 insertions(+), 5 deletions(-)
 create mode 100644 tests/qapi-schema/alternate-clash-members.err
 rename tests/qapi-schema/{alternate-clash.exit => alternate-clash-members.exit} (100%)
 rename tests/qapi-schema/{alternate-clash.json => alternate-clash-members.json} (100%)
 rename tests/qapi-schema/{alternate-clash.out => alternate-clash-members.out} (100%)
 create mode 100644 tests/qapi-schema/alternate-clash-type.err
 create mode 100644 tests/qapi-schema/alternate-clash-type.exit
 create mode 100644 tests/qapi-schema/alternate-clash-type.json
 create mode 100644 tests/qapi-schema/alternate-clash-type.out
 delete mode 100644 tests/qapi-schema/alternate-clash.err

diff --git a/scripts/qapi.py b/scripts/qapi.py
index d90399a..6c224c6 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1008,10 +1008,24 @@ class QAPISchemaObjectTypeVariants(object):
         assert isinstance(self.tag_member.type, QAPISchemaEnumType)
         for v in self.variants:
             vseen = dict(seen)
+            # TODO Ugly special case for simple unions, where the C member
+            # is named 'kind' instead of 'type'.
+            if not self.tag_name:
+                vseen['kind'] = QAPISchemaKindHack('kind',
+                                                   vseen.pop('type')._owner)
             v.check(schema, info, self.tag_member.type, vseen,
                     self.tag_name is not None)


+# TODO Ugly hack for simple unions, where the C member is named 'kind'
+class QAPISchemaKindHack(QAPISchemaObjectTypeMember):
+    def __init__(self, name, owner):
+        QAPISchemaObjectTypeMember.__init__(self, name, '', False, owner)
+
+    def describe(self):
+        return "'%s' (implicit tag of %s)" % (self.name, self._owner)
+
+
 class QAPISchemaObjectTypeVariant(QAPISchemaObjectTypeMember):
     def __init__(self, name, typ, owner):
         QAPISchemaObjectTypeMember.__init__(self, name, typ, False, owner)
diff --git a/tests/Makefile b/tests/Makefile
index 79fb154..db0f9a6 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -223,7 +223,8 @@ $(foreach target,$(SYSEMU_TARGET_LIST), \

 qapi-schema += alternate-array.json
 qapi-schema += alternate-base.json
-qapi-schema += alternate-clash.json
+qapi-schema += alternate-clash-members.json
+qapi-schema += alternate-clash-type.json
 qapi-schema += alternate-conflict-dict.json
 qapi-schema += alternate-conflict-string.json
 qapi-schema += alternate-empty.json
diff --git a/tests/qapi-schema/alternate-clash-members.err b/tests/qapi-schema/alternate-clash-members.err
new file mode 100644
index 0000000..0adf737
--- /dev/null
+++ b/tests/qapi-schema/alternate-clash-members.err
@@ -0,0 +1 @@
+tests/qapi-schema/alternate-clash-members.json:7: Alternate 'Alt1' branch 'a_b' clashes with 'a-b'
diff --git a/tests/qapi-schema/alternate-clash.exit b/tests/qapi-schema/alternate-clash-members.exit
similarity index 100%
rename from tests/qapi-schema/alternate-clash.exit
rename to tests/qapi-schema/alternate-clash-members.exit
diff --git a/tests/qapi-schema/alternate-clash.json b/tests/qapi-schema/alternate-clash-members.json
similarity index 100%
rename from tests/qapi-schema/alternate-clash.json
rename to tests/qapi-schema/alternate-clash-members.json
diff --git a/tests/qapi-schema/alternate-clash.out b/tests/qapi-schema/alternate-clash-members.out
similarity index 100%
rename from tests/qapi-schema/alternate-clash.out
rename to tests/qapi-schema/alternate-clash-members.out
diff --git a/tests/qapi-schema/alternate-clash-type.err b/tests/qapi-schema/alternate-clash-type.err
new file mode 100644
index 0000000..cdd2090
--- /dev/null
+++ b/tests/qapi-schema/alternate-clash-type.err
@@ -0,0 +1 @@
+tests/qapi-schema/alternate-clash-type.json:9: 'kind' (branch of Alt1) collides with 'kind' (implicit tag of Alt1)
diff --git a/tests/qapi-schema/alternate-clash-type.exit b/tests/qapi-schema/alternate-clash-type.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/alternate-clash-type.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/alternate-clash-type.json b/tests/qapi-schema/alternate-clash-type.json
new file mode 100644
index 0000000..629584b
--- /dev/null
+++ b/tests/qapi-schema/alternate-clash-type.json
@@ -0,0 +1,10 @@
+# Alternate branch 'type'
+# Reject this, because we would have a clash in generated C, between the
+# alternate's implicit tag member 'kind' and the branch name 'kind'
+# within the alternate.
+# TODO: Even if alternates are simplified in the future to use a simpler
+# 'qtype_code type' tag, rather than a full QAPISchemaObjectTypeMember,
+# we must still flag the collision, or else munge the generated C branch
+# names to allow compilation.
+{ 'alternate': 'Alt1',
+  'data': { 'kind': 'str', 'type': 'int' } }
diff --git a/tests/qapi-schema/alternate-clash-type.out b/tests/qapi-schema/alternate-clash-type.out
new file mode 100644
index 0000000..e69de29
diff --git a/tests/qapi-schema/alternate-clash.err b/tests/qapi-schema/alternate-clash.err
deleted file mode 100644
index 7fd3069..0000000
--- a/tests/qapi-schema/alternate-clash.err
+++ /dev/null
@@ -1 +0,0 @@
-tests/qapi-schema/alternate-clash.json:7: Alternate 'Alt1' branch 'a_b' clashes with 'a-b'
diff --git a/tests/qapi-schema/union-clash-type.err b/tests/qapi-schema/union-clash-type.err
index 451d5f2..ce7f8cd 100644
--- a/tests/qapi-schema/union-clash-type.err
+++ b/tests/qapi-schema/union-clash-type.err
@@ -1 +1 @@
-tests/qapi-schema/union-clash-type.json:10: 'type' (branch of TestUnion) collides with 'type' (member of TestUnion)
+tests/qapi-schema/union-clash-type.json:8: 'kind' (branch of TestUnion) collides with 'kind' (implicit tag of TestUnion)
diff --git a/tests/qapi-schema/union-clash-type.json b/tests/qapi-schema/union-clash-type.json
index 6101e49..cfc256b 100644
--- a/tests/qapi-schema/union-clash-type.json
+++ b/tests/qapi-schema/union-clash-type.json
@@ -2,8 +2,6 @@
 # Reject this, because we would have a clash in generated C, between the
 # simple union's implicit tag member 'kind' and the branch name 'kind'
 # within the union.
-# FIXME: Right now, the test claims the collision is on 'type'; if the
-# second branch is renamed, the code mistakenly parses successfully.
 # TODO: Even when the generated C is switched to use 'type' rather than
 # 'kind', to match the QMP spelling, the collision should still be detected.
 # Or, we could munge the branch name to allow compilation.
-- 
2.4.3